JP2004244544A - Silicate phosphor, manufacturing process for the silicate phosphor and plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fine particle phosphor having a uniform shape, a high and uniform luminous intensity. <P>SOLUTION: A precursor is formed which homogeneously contains a metal element capable of constituting the silicate phosphor by firing around a silicon-based material forming the parent nucleus of the silicate phosphor. The precursor is fired in a way that silicon compound particles do not substantially fuse. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０１２９】
表１より、本発明に係る焼成工程のように、ケイ素系材料粒子の周囲に金属元素を均一な組成で含む前駆体を、ケイ素系材料粒子同士が互いに融着しない温度で焼成することにより、金属元素を粒子内に均一に拡散混入させて結晶化することによりケイ酸塩蛍光体の発光強度が高くなるという結果が得られた。
【０１３０】
（２）粒子形状の評価
次に、上記ケイ酸塩蛍光体１−１〜１−３と、比較例１の走査型電子顕微鏡（ＳＥＭ）写真をそれぞれ図５〜８に示す。
また、走査型電子顕微鏡写真に写された蛍光体粒子を無作為に１００個選択して求めた平均粒径を表２に示す。
【表２】

【０１３１】
比較例１の製造方法により得られた蛍光体は図８に示すように、粒子同士が互いに融着した不定形状を示し、粒子間における粒子形状は不均一であった。また、使用した二酸化ケイ素（図４）とも形状が大きく異なっており、その平均粒径は０．５μｍから１．５８μｍに増大し、粒度分布にもばらつきが生じた。
【０１３２】
これに対して、図５〜７に示す様に、蛍光体１−１〜１−３は、粒子形状が均一であり、使用した二酸化ケイ素の形状と略同一なものを得ることができた。
また、その平均粒径も原料として用いた二酸化ケイ素の平均粒径と略同一で、粒度分布のばらつきも少なかった。蛍光体１−３の様に、０．０３μｍの二酸化ケイ素を用いた場合にも、図７に示す様に、粒形が均一で、粒子同士が互いに融着していないものを得ることができた。
【０１３３】
（実施例２）
１．蛍光体の製造
（１）ケイ酸塩蛍光体２−１
ケイ酸塩蛍光体１−１と同様の方法で得られた乾燥済み前駆体を、先ず、窒素１００％の雰囲気中で９５０℃、３時間焼成して二酸化ケイ素中に他の金属元素を拡散混入させた。次に、得られた粉体に対して０．１ｗｔ％の割合でアルミニウムオキサイドＣ（焼結防止剤、アエロジル製）を混合した。更に、その混合物を、窒素１００％の雰囲気中で１２００℃、３時間再焼成してケイ酸塩蛍光体２−１を得た。
【０１３４】
（２）ケイ酸塩蛍光体２−２の製造
ケイ酸塩蛍光体１−２と同様の方法で得られた乾燥済み前駆体を、先ず、窒素１００％の雰囲気中で９００℃、３時間焼成して二酸化ケイ素中に他の金属元素を拡散混入させた。その後は、ケイ酸塩蛍光体２−１と同様に再焼成してケイ酸塩蛍光体２−２を得た。
【０１３５】
（３）ケイ酸塩蛍光体２−３の製造
ケイ酸塩蛍光体１−３と同様の方法で得られた乾燥済み前駆体を、先ず、窒素１００％の雰囲気中で８００℃、３時間焼成して二酸化ケイ素中に他の金属元素を拡散混入させた。その後は、ケイ酸塩蛍光体２−１と同様に再焼成してケイ酸塩蛍光体２−３を得た。
【０１３６】
（４）比較例２の製造
ケイ酸塩蛍光体１−１と同様の方法で得られた乾燥済み前駆体を、先ず、窒素１００％の雰囲気中で９５０℃、３時間焼成して二酸化ケイ素中に他の金属元素を拡散混入させた。次に、得られた粉体を、窒素１００％の雰囲気中で１２００℃、３時間再焼成して比較例２を得た。
【０１３７】
２．評価
上記で得られたケイ酸塩蛍光体２−１〜２−３および比較例２について、（１）発光強度、（２）粒子形状について評価した。
【０１３８】
（１）発光強度の評価
ケイ酸塩蛍光体２−１〜２−３および比較例２にそれぞれ０．１〜１．５Ｐａの真空槽内でエキシマ１４６ｎｍランプ（ウシオ電機社製）を用いて紫外線を照射して、ケイ酸塩蛍光体から緑色光を発光させた。次に、得られた緑色光を検出器（ＭＣＰＤ−３０００（大塚電子株式会社製））を用いてその強度を測定した。そして、発光のピーク強度を、比較例２を１００とした相対値で求めた。得た結果を表３に示す。
【表３】

【０１３９】
表３に示すように、比較例２の様に焼結防止剤混合工程を行わずに、再焼成を行った場合と比較すると、蛍光体２−１〜２−３に示すように焼結防止剤混合工程を行った後に再焼成（結晶化工程）を行うことによりケイ酸塩蛍光体の発光強度が高くなるという結果が得られた。
【０１４０】
（２）粒子形状の評価
次に、上記ケイ酸塩蛍光体２−１〜２−３および比較例２で得たケイ酸塩蛍光体の走査型電子顕微鏡（ＳＥＭ）で粒子形状を確認したところ、上記実施例１と同様に比較例２は、粒子同士が互いに融着した不均一な形状を示すのに対し、ケイ酸塩蛍光体２−１〜２−３は、粒子形状が均一で、使用した二酸化ケイ素（ケイ素系材料）粒子と略同一の形状のケイ酸塩蛍光体が得られている事がわかった。また、その粒径もケイ酸塩蛍光体２−１〜２−３は、原料として使用した二酸化ケイ素と略同一の粒径であったが、比較例２の平均粒径は増大し、その粒度分布も広いものとなった。
【０１４１】
（実施例３）
実施例１で製造したケイ酸塩蛍光体１−１と比較例１の蛍光体について、粒子内における構成元素の組成の分布における均一性について評価した。
評価は、透過型電子顕微鏡（ＴＥＭ）を用い、電子線を照射した際に試料から発生する特性Ｘ線を解析することで粒子内部組成の定量により行った。
【０１４２】
まず、各ケイ酸塩蛍光体の試料を５０ｎｍの切片として連続的に切り出した。次に、その切片を電子顕微鏡観察用メッシュに載せてカーボン蒸着を施し、透過型電子顕微鏡を用いて特性Ｘ線の測定を行った。得られた特性Ｘの解析からＺｎ、Ｍｎ、Ｓｉの各切片における含有率の差が、各元素の含有率の理論値の２０％以下である粒子を組成分布が微視的に均一な粒子とした。
１００個のケイ酸塩蛍光体について同様な測定を行い、組成分布が微視的に均一である粒子の比率を算出した。測定結果を表４に示す。
【表４】

【０１４３】
表４に示すように、本発明に係る蛍光体１−１の粒子内における構成元素の組成の分布が極めて均一であることが分かる。
【０１４４】
（実施例４）
実施例１で製造したケイ酸塩蛍光体１−１と比較例１の蛍光体について、粒子内に含有される構成元素の含有率について評価を行った。
まず、二次イオン質量分析（ＳＩＭＳ）装置を用いて、相対感度係数を用いて一個一個の粒子の組成を定量した。次に、粒子内に含有される構成元素の含有率の粒子間における変動係数を１００個の粒子を測定して求めた。
なお、変動係数は、各粒子内に含有される構成元素の含有率を測定した際の組成含有率の標準偏差を平均含有率で除した値に１００を乗じて求めた。測定結果を表５に示す。
【表５】

【０１４５】
表５に示すように、本発明に係る蛍光体１−１の粒子内に含有される構成元素の含有率の粒子間における変動が少ないことが分かる。
【０１４６】
（実施例５）
実施例１で製造した蛍光体１−１〜１−３および比較例１と、下記に示す方法で青色蛍光体Ｂと、赤色蛍光体Ｒを製造し、これらの蛍光体を含む蛍光体層を備えたＰＤＰを製造し、白色輝度について評価した。
なお、蛍光体１−１〜１−３および比較例１はそれぞれ組成式Ｚｎ_２ＳｉＯ_４：Ｍｎで表される緑色蛍光体である。
【０１４７】
１．蛍光体の製造
（１）青色蛍光体Ｂの製造
原料として炭酸バリウム（ＢａＣＯ_３）、炭酸マグネシウム（ＭｇＣＯ_３）、酸化アルミニウム（α−Ａｌ_２Ｏ_３）をモル比で１対１対５に配合する。次に、この混合物に対して、所定量の酸化ユーロピウム（Ｅｕ_２Ｏ_３）を添加する。そして、適量のフラックス（ＡｌＦ_２，ＢａＣｌ_２）と共にボールミルで混合し、１，６００℃で３時間、窒素９５％、水素５％の還元雰囲気中で焼成して蛍光体を得た。得られた蛍光体を分級し、平均粒径１．５μｍのものを青色蛍光体Ｂとした。
【０１４８】
（２）赤色蛍光体Ｒの製造
原料として酸化イットリウム（Ｙ_２Ｏ_３）と酸化ガドリニウム（Ｇｄ_２Ｏ_３）と硼酸（Ｈ_３ＢＯ_３）とを、Ｙ，Ｇｄ，Ｂの原子比で０．６０：０．３５：１．０となるように配合する。次に、この混合物に対して、所定量の酸化ユーロピウム（Ｅｕ_２Ｏ_３）を添加する。適量のフラックスと共にボールミルで混合し、１４００℃で３時間、大気雰囲気中で焼成してケイ酸塩蛍光体を得た。得られた蛍光体を分級し、平均粒径１．５μｍのものを赤色蛍光体Ｒとした。
【０１４９】
２．蛍光体塗布液の作製
上記方法で得られた青色蛍光体Ｂ、赤色蛍光体Ｒと、蛍光体１−１〜１−３および比較例１のそれぞれを用いて、エチルセルロース、ポリオキシエチレンアルキルエーテル、ターピネオールおよびペンタンジオールの１：１混合液から蛍光体塗布液Ｂ、Ｒ、Ｇ−１〜Ｇ−３および比較例Ｇを作製した。
【０１５０】
３．ＰＤＰの製造
（１）ＰＤＰ１の製造
上記で調整した青色蛍光体塗布液Ｂ、赤色蛍光体塗布液Ｒ、緑色蛍光体塗布液Ｇ−１を用いて、図１に示す４２インチのＰＤＰを以下のように製造した。
まず、前面板１０となるガラス基板上に、走査電極１１ａと維持電極１１ｂとを径が５０μｍのノズルを用いてインクジェット法により形成した。このとき、ノズル先端と前面板との距離を１ｍｍに保った状態で、ノズル先端を前面板１０上の所定の位置を走査しながら電極材インキを吐出して、電極幅６０μｍの走査電極１１ａと維持電極１１ｂをそれぞれ形成した。
【０１５１】
次に、前面板１０上に、前記電極１１を介して低融点ガラスを印刷し、これを５００〜６００℃で焼成することにより誘電体層１２を形成し、さらにこの上に、ＭｇＯを電子ビーム蒸着して保護膜１３を形成した。
【０１５２】
一方、背面板２０となるガラス基板上に、データ電極２１を形成した。データ電極２１も、上記と同様に、径が５０μｍのノズルを用いて、背面板２０との距離を１ｍｍに保った上で、所定の位置を走査させながら、６０μｍ幅のものを形成した。次に、このデータ電極の両側方に位置するように、低融点ガラスを用いてストライプ状の隔壁３０を形成した。隔壁３０同士の間隔（ピッチ）は０．３６ｍｍに、隔壁３０の高さは０．１５ｍｍとした。
【０１５３】
さらに、前記隔壁３０により仕切られたセル３１の内側に面する底面３１ａと前記隔壁３０の側面３０ａとに、上記２．で作製した蛍光体塗布液Ｂ、Ｒ、Ｇ−１を隣り合うセルに一色ずつ規則正しい順序で塗布した。
【０１５４】
そして、前記電極１１、２１等が配置された前面板１０と上記背面板２０とを、それぞれの電極配置面が向き合うように位置合わせし、隔壁３０により約１ｍｍのギャップを保った状態で、その周辺をシールガラスにより封止した。そして、前記基板１０、２０間に、放電により紫外線を発生するキセノン（Ｘｅ）と主放電ガスのネオン（Ｎｅ）とを混合したガスを封入して気密密閉した。なお、キセノンとネオンの混合体積比は、１：９とし、封入圧力は６６．７ｍＰａとした。その後、エージングを行い、ＰＤＰ１とした。
【０１５５】
（２）ＰＤＰ２の製造
緑色蛍光体塗布液として、Ｇ−２を用いた以外は、ＰＤＰ１と同様にしてＰＤＰを製造し、ＰＤＰ２とした。
【０１５６】
（３）ＰＤＰ３の製造
緑色蛍光体塗布液として、Ｇ−３を用いた以外は、ＰＤＰ１と同様にしてＰＤＰを製造し、ＰＤＰ３とした。
【０１５７】
（４）比較例３の製造
緑色蛍光体塗布液として、比較例Ｇを用いた以外は、ＰＤＰ１と同様にしてＰＤＰを製造し、比較例とした。
【０１５８】
４．評価
上記において得られたＰＤＰ１〜３および比較例のそれぞれについて、パネル全面が点灯している時の放電維持電圧で、周波数３０ＫＨｚで駆動させた時の輝度を測定し、Ｐ−１のパネル輝度を１００とした相対値で表した。評価結果を表６に示す。
【表６】

【０１５９】
表６より、比較例１により製造した蛍光体を用いて緑色蛍光体層を形成する場合と比較すると、本願に係る蛍光体１−１〜１−３を用いて緑色蛍光体層を形成した方が、ＰＤＰのパネル輝度も向上することが分かった。
【０１６０】
また、目視にて確認したところ、比較例３のパネルと比べるとＰＤＰ１〜３は発光ムラ等もなく画像を美しく表示することができた。
【０１６１】
【発明の効果】
請求項１に記載の発明によれば、ケイ酸塩蛍光体の粒子同士が互いに融着した不定形状ではないので、蛍光体粒子を一定の大きさ、一定の形状にするための機械的な粉砕処理等を行う必要がなく、結晶欠陥による発光強度の低下を防止することができる。さらに、極めて微粒子であり、かつ、粒子間で形状も揃っているので、ＰＤＰの蛍光体層に用いた場合、そのセルの発光強度を向上することができる。
【０１６２】
請求項２に記載の発明によれば、極めて微粒子の蛍光体で、粒径分布の変動係数の値が小さく、大きさ、形状が粒子間で略同一であるので、どのような用途に用いても輝度の高いムラのない発光を行うことができる。また、ＰＤＰのセルに設けられる蛍光体層に密に蛍光体を充填することができ、セルの発光強度を向上することができる。
【０１６３】
請求項３に記載の発明によれば、粒子内における構成元素の組成の分布が均一である粒子が粒子数で５０％以上を占めているので、粒子の発光特性が均一になる。したがって、ＰＤＰのセルの蛍光体層をこの蛍光体で構成することにより、発光ムラのない秀麗なものとすることができる。
【０１６４】
請求項４に記載の発明によれば、粒子内における各構成元素の含有率の粒子間分布の変動係数が５０％以下であるので、各粒子が含有する構成元素量のばらつきがなく、ムラのない発光を行うことができる。
【０１６５】
請求項５に記載の発明によれば、前駆体形成工程においてケイ素系材料粒子の周囲に、焼成することによりケイ酸塩蛍光体を構成し得る金属元素を均一な組成で含む前駆体を形成し、焼成工程において金属元素をケイ素系材料粒子内に拡散混入させるので、組成の均一な蛍光体を得ることができる。また、前駆体を焼成する際に、ケイ素系材料粒子の融着が実質的に起こらない状態とするので、得られる蛍光体粒子が互いに融着して不定形状となることを防止することができる。
【０１６６】
請求項６に記載の発明によれば、ケイ酸塩蛍光体を製造する際の効率を向上することができる
【０１６７】
請求項７に記載の発明によれば、液相法により前駆体を形成するので、ケイ素系材料と、ケイ酸塩蛍光体を構成するケイ素以外の金属元素とが液体内で均一に混合することができ、反応条件を整えることによって粒子内で構成元素が均一に拡散、分布し、構成元素の含有率が均一な蛍光体を得ることができる。
【０１６８】
請求項８記載の発明によれば、ケイ酸塩蛍光体は請求項１〜４のいずれか一項と同様の効果が得られる。
【０１６９】
請求項９記載の発明によれば、ＰＤＰは、請求項１〜５、９のいずれか一項に記載のケイ酸塩蛍光体を含有する蛍光体層を有するので、蛍光体層にケイ酸塩蛍光体を密に充填することができ、これによりセルの発光強度を向上することができる。
【図面の簡単な説明】
【図１】本発明の一例のプラズマディスプレイパネルを示した概略構成図である。
【図２】図１に示したプラズマディスプレイパネルに設けられた電極の配置を示した概略平面図である。
【図３】本発明に係る蛍光体の製造方法において使用する反応装置の一例を示した概略図である。
【図４】実施例１において、原料として使用した二酸化ケイ素を示した走査型電子顕微鏡写真である。
【図５】実施例１で製造した蛍光体１−１の走査型電子顕微鏡写真である。
【図６】実施例１で製造した蛍光体１−２の走査型電子顕微鏡写真である。
【図７】実施例１で製造した蛍光体１−３の走査型電子顕微鏡写真である。
【図８】比較例１の蛍光体を示した走査型電子顕微鏡写真である。
【符号の説明】
１ プラズマディスプレイパネル
３５ 蛍光体層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to silicate phosphors and silicate phosphors that can be widely used for devices such as display devices such as plasma display panels and lighting devices such as thin-tube fluorescent lamps, electronic devices, and various silicate phosphor-use articles. And a plasma display panel.
[0002]
[Prior art]
The phosphor converts the energy of the excitation rays into light (ultraviolet rays, visible light, infrared rays, etc.) by irradiating the excitation rays (ultraviolet rays, visible light, infrared rays, heat rays, electron beams, X-rays, radiations, etc.). Material. Phosphors are used in various articles such as fluorescent paints, ashtrays, stationery, outdoor goods, guide boards, guides, and signs such as safety signs. In addition, various devices such as a fluorescent lamp, an electron tube, a fluorescent display tube, an electroluminescence panel, a scintillation detector, an X-ray image intensifier, a thermofluorescence dosimeter and an imaging plate, a cold cathode display (FED), a plasma display It is also applied to a display device such as a panel (PDP) (for example, see "Phosphor Handbook", edited by Phosphors Society of Japan, Ohmsha).
[0003]
Among the display devices listed above, PDPs have attracted attention as flat panel displays that can replace cathode ray tubes (CRTs), because their screens can be made larger and thinner. A PDP has a glass substrate provided with two electrodes and a large number of minute discharge spaces (hereinafter, referred to as cells) formed by partition walls provided between the substrates. Phosphor layers that emit red, green, blue, and the like are provided on the side and bottom surfaces (one glass substrate) of the partition surrounding each cell.
[0004]
The cells are formed in a predetermined shape by partition walls, are arranged regularly on the substrate, and are filled with a discharge gas mainly composed of Xe, Ne or the like. The cell suppresses the spread of the discharge to a certain area. When a voltage is applied between the electrodes and the cell is discharged, ultraviolet rays caused by the discharge gas are generated, and the phosphor is excited to emit visible light. . Desired information can be displayed in full color by selectively discharging a cell or a part of the cell.
[0005]
At present, (Y, Gd) BO is mainly used as a phosphor for PDP. ₃ : Eu (red), Zn ₂ SiO ₄ : Mn (green), BaMgAl ₁₀ O ₁₇ : Eu (blue) and the like. These phosphors are generally manufactured by a solid phase method. The solid phase method is a method in which a predetermined amount of a compound containing an element constituting a phosphor matrix and a compound containing an activator element are mixed and fired at a predetermined temperature to obtain a phosphor by a solid-phase reaction (“Fluorescence”). Body Handbook ”). The phosphor thus obtained generally has a flat particle shape or an irregular polyhedral shape.
[0006]
2. Description of the Related Art In recent years, cells have been miniaturized with the increase in definition of displays such as PDPs. In order to obtain a predetermined luminance, a certain amount or more of phosphor must be filled in each phosphor layer provided in each cell. However, if the particle shape is flat or irregular and polyhedral as described above, the phosphor layer becomes thicker accordingly. When the thickness of the phosphor layer is large, not only scattering of light emitted from the phosphor is increased, but also a discharge space is narrowed, and it becomes impossible to generate ultraviolet rays sufficient to excite the phosphor. In particular, green phosphors have high visibility and are required to improve the luminance of green cells.
[0007]
Therefore, in order to densely fill the phosphor layer with the green phosphor, for example, a spherical phosphor (Zn) having a spherical or nearly spherical polymethylsilsesquioxy acid as a base material is used. ₂ SiO ₄ : Mn) (for example, see Patent Document 1).
[0008]
[Patent Document 1]
JP-A-9-278446
[0009]
[Problems to be solved by the invention]
However, with the miniaturization of the cell structure of the PDP, finer phosphor particles have been required. However, Patent Document 1 discloses a solid-phase method in which a relatively large (4.5 μm to 2 μm) spherical fluorescent particle is used. Only a method of obtaining the body is disclosed. Since the method described in Patent Document 1 is a solid phase method, it is necessary to perform a step such as pulverization when producing finer phosphors, and at this time, the shape of the phosphor particles may not be uniform. . Further, crystal distortion or the like may be caused during the pulverizing step, and the luminous intensity may decrease. Furthermore, since the raw material powder is dry-mixed, it is difficult to control the composition of the constituent elements uniformly, and it is difficult to uniformly diffuse and mix the activator into the mother nucleus particles of the phosphor. There was a possibility that a sufficient emission intensity could not be obtained.
[0010]
An object of the present invention is to provide a fine particle silicate phosphor having a uniform shape, high luminous intensity and no luminous unevenness, a method for producing the same, and a PDP using the silicate phosphor.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 provides a method in which a metal element capable of constituting a silicate phosphor by diffusion into a silicon-based material constituting a mother nucleus of the silicate phosphor is diffused and mixed. Silicate phosphor having an average particle size of 0.01 to 1 μm, and the particles are not fused to each other.
[0012]
According to the first aspect of the present invention, the metal element is diffused and mixed into the silicon-based material constituting the mother nucleus of the silicate phosphor, and the particles do not have an irregular shape fused to each other. There is no need to perform a mechanical pulverizing process or the like for forming particles into a certain size and a certain shape, and it is possible to prevent a decrease in light emission intensity due to crystal defects, and it can be suitably used for various applications.
[0013]
Furthermore, since the particles are extremely fine particles having an average particle diameter of 0.01 to 1 μm and the shapes are uniform among the particles, the phosphor is densely filled even in the phosphor layer of PDP in which the cell structure is miniaturized. And the light emission intensity of the cell can be improved.
[0014]
The invention according to claim 2 is a silicate phosphor in which a metal element capable of constituting a silicate phosphor is diffused and mixed by firing on a silicon-based material constituting a mother nucleus of the silicate phosphor. The average particle size is 0.01 to 1 μm, the value of the variation coefficient of the particle size distribution is 40% or less, and the shapes of the individual particles are substantially the same.
[0015]
According to the invention of claim 2, the phosphor is an extremely fine particle having an average particle diameter of 0.01 to 1 μm, has a variation coefficient of particle diameter distribution of 40% or less, and has a size and shape between particles. Since they are substantially the same, light emission with high luminance and no unevenness can be performed regardless of the application. Further, the phosphor can be densely filled in the phosphor layer provided in the cell of the PDP, and the emission intensity of the cell can be improved.
[0016]
According to a third aspect of the present invention, in the silicate phosphor according to the first or second aspect, particles having a uniform composition distribution of constituent elements in the particles are 50% or more in number of particles. And
[0017]
According to the third aspect of the present invention, the particles having a uniform composition distribution of the constituent elements in the particles occupy 50% or more in the number of particles, so that the light emission characteristics of the particles become uniform. Therefore, by forming the phosphor layer of the cell of the PDP with this phosphor, it is possible to obtain an excellent one with no light emission unevenness.
[0018]
According to a fourth aspect of the present invention, in the silicate phosphor according to any one of the first to third aspects, the coefficient of variation of the interparticle distribution of the content of the constituent elements in the particles is 50% or less. It is characterized by the following.
[0019]
According to the fourth aspect of the present invention, since the variation coefficient of the inter-particle distribution of the content of each constituent element in the particle is 50% or less, there is no variation in the amount of the constituent element contained in each particle, and the unevenness is reduced. No light emission can be performed.
[0020]
The invention according to claim 5 is a precursor including a metal element capable of constituting a silicate phosphor by firing around a silicon-based material particle serving as a mother nucleus of the silicate phosphor in a uniform composition. And baking in a state where the fusion of the silicon-based material particles does not substantially occur to obtain a silicate phosphor in which the metal element is diffused and mixed inside the silicon-based material particles. And a firing step.
[0021]
According to the invention as set forth in claim 5, in the precursor forming step, a precursor containing a metal element capable of constituting a silicate phosphor in a uniform composition is formed around the silicon-based material particles by firing. Since the metal element is diffused and mixed into the silicon-based material particles in the firing step, a phosphor having a uniform composition can be obtained.
[0022]
In addition, since the fusion of the silicon-based material particles does not substantially occur when the precursor is fired, it is possible to prevent the resulting phosphor particles from being fused to each other and becoming an irregular shape. . Therefore, it is possible to obtain a silicate phosphor having a small variation coefficient of the particle size distribution and having a uniform shape between particles.
In addition, there is no need to perform a mechanical pulverizing process or the like for making the phosphor particles have a certain size and a certain shape, and it is possible to prevent a decrease in light emission intensity due to crystal defects.
[0023]
According to a sixth aspect of the present invention, in the method for producing a silicate phosphor according to the fifth aspect, the firing step includes firing the precursor in a state where the fusion of the silicon-based material particles does not substantially occur. Performing a metal element diffusion mixing step of diffusing and mixing the metal element inside the silicon-based material particles, and a sintering inhibitor mixing step of mixing a sintering inhibitor into the fired product obtained in the metal element diffusion mixing step And a crystallization step of re-baking the mixture obtained in the sintering inhibitor mixing step to obtain a crystallized silicate phosphor.
[0024]
According to the sixth aspect of the present invention, it is possible to improve the efficiency in producing the silicate phosphor. That is, in order to diffuse and mix the metal element into the silicon-based material in a state where the fusion of the silicon-based material does not substantially occur, it is necessary to perform firing at a temperature equal to or lower than the melting point of the silicon-based material. On the other hand, since a predetermined amount of energy is required to crystallize the phosphor to a desired state, firing at a low temperature requires firing for a long time. However, in the present invention, after the metal element diffusion mixing step, the obtained fired product is mixed with a sintering inhibitor, so that the crystallization step is performed at a higher firing temperature than the metal element diffusion mixing step in a state where particles are not fused. It can be fired at a temperature. Therefore, the efficiency of manufacturing the phosphor can be improved.
[0025]
According to a seventh aspect of the present invention, in the method for producing a silicate phosphor according to the fifth or sixth aspect, the precursor forming step is performed by a liquid phase method.
[0026]
According to the invention of claim 7, since the precursor is formed by the liquid phase method, the silicon-based material and the metal element other than silicon constituting the silicate phosphor are uniformly mixed in the liquid. By adjusting the reaction conditions, the constituent elements can be uniformly diffused and distributed in the particles, and a phosphor having a uniform content of the constituent elements can be obtained.
[0027]
The invention according to claim 8 is characterized by being obtained by the method for producing a silicate phosphor according to any one of claims 5 to 7.
[0028]
According to the invention of claim 8, the silicate phosphor has the same effect as any one of claims 1 to 4.
[0029]
According to a ninth aspect of the present invention, there is provided a plasma display panel including a phosphor layer containing the silicate phosphor according to any one of the first to fourth and eighth aspects.
[0030]
According to the ninth aspect of the present invention, the PDP has the phosphor layer containing the silicate phosphor according to any one of the first to fifth and ninth aspects. Phosphors can be densely packed, thereby improving the light emission intensity of the cell.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The silicate phosphor according to the present invention is a metal element (hereinafter, referred to as a “metal element”) capable of forming a silicate phosphor by firing in silicon-based material particles serving as a mother nucleus of the phosphor. Are diffused and mixed.
[0032]
Here, the silicon-based material refers to silicon (simple substance) or a silicon compound. In addition, the mother nucleus of the silicate phosphor substantially refers to a silicon-based material, and refers to particles having substantially no change in particle size and shape before and after firing.
[0033]
Examples of the metal element include one or more metal elements selected from the group consisting of Zn, Mn, Mg, Ca, Sr, Ba, Y, Zr, Al, Ga, La, Ce, Eu, and Tb. . These metal elements can be appropriately selected according to the composition of the silicate phosphor to be manufactured. For example, Zn ₂ SiO ₄ : When producing a silicate phosphor represented by the composition formula of Mn, Zn and Mn may be selected. By appropriately selecting and using these metal elements, a silicate phosphor having desired light emission can be obtained.
[0034]
As such a silicate phosphor, specifically, Zn ₂ SiO ₄ : Mn / (Sr, Ba) Al ₂ Si ₂ O ₈ : Eu / (Ba, Mg) ₂ SiO ₄ : Eu / Y ₂ SiO ₅ : Ce, Tb / Sr ₂ Si ₃ O ₈ -2SrCl ₂ : Eu / Zr ₂ SiO ₄ , MgAl ₁₁ O ₁₉ : Ce, Tb / Ba ₂ SiO ₄ : Eu / Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Eu and the like.
[0035]
The individual particles of the silicate phosphor according to the present invention are not fused to each other, and their shapes (grain shapes) are substantially the same. The particle shape may be any shape such as a sphere, a rod, a flat plate, and the like.
[0036]
The average particle size of the silicate phosphor in the present invention is in the range of 0.01 to 1 μm, more preferably in the range of 0.01 to 0.5 μm, and still more preferably in the range of 0.01 to 0.3 μm. It is.
[0037]
The average particle size refers to the length of the particle when the particles are cubic or octahedral so-called normal crystals. In the case where the crystal is not a normal crystal, for example, in the case of a sphere, a rod, or a plate, it refers to the diameter of a sphere equivalent to the particle volume.
[0038]
Preferably, the particles are monodispersed. To be monodisperse specifically means that the value of the variation coefficient of the particle size distribution obtained by the following equation (1) is small. Specifically, the value of the variation coefficient of the particle size distribution is preferably 40% or less, more preferably 30% or less, and even more preferably 0.1 to 20%.
[Equation 1]
Coefficient of variation of particle size distribution = (standard deviation of particle size / average value of particle size) × 100 (1)
[0039]
In the present invention, it is preferable that the metal element is uniformly diffused and mixed into the silicon-based material particles. Specifically, in the particles of the silicate phosphor, the constituent elements of the silicate phosphor are The number of particles having a uniform composition distribution is preferably 50% or more, more preferably 60% or more, and most preferably 80% or more.
[0040]
Here, that the distribution of the composition of the constituent elements in the particle is uniform indicates that the composition is microscopically constant in any region in one phosphor particle. More specifically, in a microscopic distribution measuring method described later, it means that the difference in the content of each section of a certain composition is 20% or less of the theoretical value of the content of the composition.
[0041]
As a method of measuring the microscopic distribution of the composition in the particles, a transmission electron microscope (TEM) is used to analyze characteristic X-rays generated from a sample when irradiated with an electron beam, thereby analyzing each particle. The internal composition distribution can be measured. It is possible to continuously cut out the silicate phosphor particles as a sample, for example, as a section having a thickness of about 50 nm, place the section on a mesh for electron microscope observation, perform carbon deposition, and observe by a transmission method. is there.
[0042]
As a method of calculating the ratio of particles whose composition distribution is microscopically uniform, the internal composition distribution of at least 100 silicate phosphor particles is measured by a transmission electron micrograph in the same manner as described above, and a certain composition is measured. What is necessary is just to calculate the ratio occupied by particles in which the difference in the content of each section is 20% or less of the theoretical value of the content of the composition.
[0043]
Further, the variation rate of the inter-particle distribution of the content of the constituent elements in the particles is preferably 50% or less, more preferably 30% or less, and most preferably 15% or less.
[0044]
As a method of measuring the content of the constituent elements contained in the particles, a composition of each particle is measured using a secondary ion mass spectrometer (SIMS) having a high resolution of submicron to nanometer order. be able to. At this time, it is preferable that the silicate phosphor particles according to the present invention be placed on a sample stage, and carbon and the like be deposited and measured. In particular, when measuring silicate phosphor particles having a particle size of 1 μm or less, the measurement can be performed by crushing the particles to a certain thickness.
[0045]
The coefficient of variation of the interparticle distribution of the content of the constituent elements contained in the particles is determined by the secondary ion mass spectrometer using the content of the constituent elements contained in each of the at least 100 silicate phosphor particles. It can be obtained by multiplying the value obtained by dividing the standard deviation of the composition content at the time of measurement by the average content by 100.
[0046]
Next, a method for producing the silicate phosphor will be described.
In the method for producing a silicate phosphor according to the present invention, a metal element (which can constitute a silicate phosphor by firing) is provided around silicon-based material particles serving as a mother nucleus of the silicate phosphor. Forming a precursor containing a uniform composition of the silicon-based material particles, and baking in a state where the fusion of the silicon-based material particles does not substantially occur, and a metal element diffused and mixed into the silicon-based material particles. Baking step to obtain a salt phosphor.
[0047]
First, the precursor forming step will be described.
The precursor forming step is preferably performed by a so-called liquid phase method in which a precursor is formed by mixing a dispersion or solution in which an element serving as a raw material of a silicate phosphor is dispersed or dissolved. The precursor formation step may be performed by a solid phase method as long as the constituent elements can be uniformly mixed.However, the solid phase method is intended to produce a fine particle phosphor for performing a mechanical dispersion / pulverization step during production. There is a possibility that crystal defects and the like are generated, and deterioration of luminance characteristics and the like is caused. On the other hand, the liquid phase method has no mechanical dispersion / pulverization process and can uniformly mix the constituent elements of the phosphor in the liquid phase, thus forming the silicate phosphor during the reaction. The dispersion of each ion is extremely good. As a result, the composition is highly stoichiometric and the composition of the metal element deposited around the silicon-based material particles tends to be uniform. In addition, the reaction efficiency is high because the reaction is between liquid phases.
[0048]
The element serving as the raw material of the silicate phosphor refers to silicon and a metal element that can form the silicate phosphor together with the silicon-based material by firing as described above. Silicon and these metal elements may be used alone, or may be oxides or various metal compounds such as chlorides and nitrates.
[0049]
As the liquid phase method, a general liquid phase method such as a coprecipitation method, a reaction crystallization method, and a sol-gel method can be used. In particular, a silicon compound such as silica (silicon-based material) is used as a mother nucleus of a precursor. Preferably, the precursor is formed by a coprecipitation method. By forming the precursor in this way, a silicate phosphor having higher emission intensity can be obtained. Further, when the precursor is formed by the reaction crystallization method or the sol-gel method, it is preferable to perform the formation with the addition of a protective colloid described below from the viewpoint of obtaining a finer phosphor having a narrow particle size distribution.
[0050]
First, the coprecipitation method will be described. The co-precipitation method uses a co-precipitation phenomenon to mix a solution containing an element that is a raw material of a phosphor, and then add a precipitant to sinter around a mother nucleus of a phosphor precursor. A method of synthesizing a phosphor precursor in a state in which a metal element or the like which can constitute a silicate phosphor is precipitated. Here, the coprecipitation phenomenon refers to a phenomenon in which, when a precipitate is generated from a solution, ions that have sufficient solubility under the circumstances and should not precipitate are accompanied by the precipitation. In the production of a phosphor, it refers to a phenomenon in which a metal element or the like constituting an activator precipitates around a mother nucleus of a phosphor precursor.
[0051]
Hereinafter, a method of producing a silicate phosphor using the silicon-based material particles as a mother nucleus of a precursor using this coprecipitation method is referred to as a silica mother nucleus method.
[0052]
To form a precursor by the silica core method, a silicon-based liquid in which a silicon-based material is dispersed in a liquid, a metal element dissolved in a liquid in a cation state, or a metal element in a liquid in a solid state It is mixed with the metallic liquid dispersed as it is.
[0053]
In the silica core method, silicon dioxide (silica) can be particularly preferably used as the silicon-based material. As the silicon dioxide, for example, fumed silica, wet silica, colloidal silica and the like can be used. In the case of colloidal silica, an anionic one is particularly preferable.
[0054]
The primary particle size or the secondary aggregation particle size of the silicon-based material particles in the present invention is preferably 1 μm or less, more preferably 0.5 μm or less, further preferably 0.1 μm or less, and most preferably 0.01 μm or less. . By controlling the primary particle size or the secondary aggregate particle size of the silicon-based material particles, the average particle size of the silicate phosphor after firing can be made a desired size.
[0055]
The primary particle size refers to a particle size when one crystallite is a primary particle. The term “secondary aggregate particle size” refers to the particle size of secondary aggregated particles formed by aggregation of primary particles of a silicon-based material in a liquid.
[0056]
The liquid for dispersing the silicon-based material may be any liquid as long as the silicon-based material is not substantially dissolved, and is preferably water or alcohols or a mixture thereof. The alcohol may be any as long as the silicon-based material is dispersed, and examples thereof include methanol, ethanol, isopropanol, propanol, and butanol. Among them, ethanol in which the silicon-based material is relatively easily dispersed is preferable.
[0057]
Here, “does not substantially dissolve the silicon-based material” refers to a range where the solubility of the silicon-based material in a liquid is 0.1% or less.
[0058]
It is desirable that the dispersion state of the silicon-based material in the liquid, the secondary aggregation particle size, and the like be adjusted in advance to obtain a desired state.
When the above-mentioned colloidal silica is used, since the particle size and the dispersion state in the liquid are prepared in advance, an appropriate one may be used as appropriate.
[0059]
By preparing the silicon-based liquid material in advance or using colloidal silica, the dispersion state of the silicon-based material in the liquid is improved, and the secondary aggregated particle size and the like become constant.
[0060]
Next, the metal-based liquid will be described.
The liquid for dissolving or dispersing the metal element may be any liquid as long as it does not substantially dissolve the silicon-based material, and is preferably water or alcohols or a mixture thereof, as described above. Examples of alcohols include methanol, ethanol, isopropanol, propanol, butanol and the like. Particularly, ethanol is preferred.
[0061]
In the silica core method, when mixing the silicon-based liquid and the metal-based liquid, a solution containing a precipitant that reacts with a metal element to form a precipitate may be mixed.
[0062]
Here, the solution containing a precipitant refers to a solution in which the following precipitant is dissolved in water, alcohols, or a mixture thereof. Specific examples of the alcohols include methanol, ethanol, isopropanol, propanol, and butanol, and any alcohol may be used as long as the silicon-based material is dispersed.
[0063]
As a precipitant, an organic acid or an alkali hydroxide can be preferably used. Organic acids or alkali hydroxides react with metal elements to form organic acid salts or hydroxides as precipitates. At this time, it is preferable that these precipitates are deposited around the silicon-based material serving as the mother nucleus.
[0064]
The amount of the precipitant used is preferably at least one time the stoichiometric amount required for the metal element to precipitate as a precipitate such as an organic acid salt or a hydroxide.
[0065]
As the organic acid, those having a carboxylic acid group (—COOH) are preferable, and specific examples thereof include oxalic acid, formic acid, acetic acid, and tartaric acid. Further, oxalic acid, formic acid, acetic acid, tartaric acid, etc. may be generated by hydrolysis or the like.
[0066]
The alkali hydroxide may be any one having a hydroxyl group (-OH), or any one which reacts with water to generate a hydroxyl group or generates a hydroxyl group by hydrolysis. Examples of the alkali hydroxide include ammonia and sodium hydroxide. , Potassium hydroxide, urea and the like. Among them, ammonia is preferably used, and particularly preferably ammonia containing no alkali metal.
[0067]
Next, the reaction crystallization method and the sol-gel method will be described.
The reaction crystallization method is a method of synthesizing a precursor by mixing a solution containing a silicon-based material and a metal element other than silicon as a raw material of a precursor of a silicate phosphor using a crystallization phenomenon. Say. These are preferably, for example, chlorides, nitrates, sulfates, and the like, and are preferably dissolved in a solvent in a cation state. For example, as the silicon-based material, sodium metasilicate can be preferably used.
[0068]
The crystallization phenomenon refers to a change in the physical or chemical environment due to cooling, evaporation, pH adjustment, concentration, etc., or a change in the state of a mixed system due to a chemical reaction. Refers to the phenomenon of precipitation.
The method for producing a precursor by the reaction crystallization method in the present invention means a production method by a physical or chemical operation that can cause the occurrence of the crystallization phenomenon as described above.
[0069]
The sol-gel method generally means a double alkoxide, a metal halide, an organic acid prepared by adding a silicon-based material or a metal element other than silicon as a raw material of a precursor to a metal alkoxide or a metal complex or an organic solvent solution thereof and adding a simple metal. In a required amount as a metal salt, a metal simple substance or the like, and thermally or chemically polycondensing. For example, as a silicon-based material, Si (OCH ₃ ) ₄ Etc. can be used.
[0070]
As a solvent for applying the above-mentioned reaction crystallization method or sol-gel method, any solvent can be used as long as the reaction raw materials are dissolved, but water is preferable from the viewpoint of easy control of the degree of supersaturation. In the case of the sol-gel method, a mixed solution of water and an alcohol such as ethanol is also a preferable embodiment. The order of adding the reaction raw materials to the solvent may be simultaneous or different, and an appropriate order can be appropriately assembled depending on the activity.
[0071]
When forming a precursor using the above-mentioned reaction crystallization method, sol-gel method, or the like, it is preferable to adjust various physical property values such as reaction temperature, addition speed and addition position, stirring conditions, pH and the like. It is also preferable to add a protective colloid or a surfactant for controlling the average particle size. Concentration or aging of the liquid as needed after the addition of the raw materials is also one of the preferred embodiments.
[0072]
In particular, by adding a protective colloid, the particle size and agglomeration state of the precursor particles can be controlled, and the average particle size of the phosphor particles after firing is a desired size in the range of 0.01 to 1.0 μm. It is preferable because it can be reduced.
[0073]
As such a protective colloid, various polymer compounds can be used regardless of whether they are natural or artificial, and proteins are particularly preferable. At that time, the average molecular weight of the protective colloid is preferably 10,000 or more, more preferably 10,000 or more and 300,000 or less, particularly preferably 10,000 or more and 30,000 or less.
[0074]
Examples of the protein include gelatin, a water-soluble protein, and a water-soluble glycoprotein. Specific examples include albumin, ovalbumin, casein, soy protein, synthetic protein, and protein synthesized by genetic engineering. Among them, gelatin can be particularly preferably used.
[0075]
Examples of gelatin include lime-treated gelatin and acid-treated gelatin, and these may be used in combination. Further, hydrolysates of these gelatins and enzymatic degradation products of these gelatins may be used.
[0076]
The protective colloid does not need to have a single composition, and various kinds of binders may be mixed. Specifically, for example, a graft polymer of the above gelatin and another polymer can be used.
[0077]
The protective colloid can be added to one or more of the raw material solutions. It may be added to all of the raw material solutions. By forming the precursor in the presence of the protective colloid, the precursors can be prevented from aggregating, and the precursor can be made sufficiently small. This makes it possible to improve various characteristics of the phosphor, such as making the phosphor after firing finer, having a narrower particle size distribution, and improving light emission characteristics. When the reaction is performed in the presence of a protective colloid, it is necessary to sufficiently control the particle size distribution of the precursor and eliminate impurities such as by-product salts.
[0078]
Regardless of the use of any of the above-described coprecipitation, reaction crystallization, and sol-gel methods, it is desirable to uniformly mix the respective liquids in the precursor formation step. The method of mixing the respective liquids is not particularly limited. For example, a mixing method by stirring is preferable because the mixing state and the like can be easily controlled and the cost is low. As a mixing method, any method such as a batch method, a continuous method, and external circulation mixing may be used.
[0079]
Specifically, a method in which a silicon-based liquid is used as a mother liquor (ground) and a metal-based liquid is added to the mother liquor while stirring the mother liquor, or the mother liquor is externally circulated to a mixer provided in an external circulation path A method of adding a metal-based liquid material, or a method of simultaneously adding a silicon-based liquid material and a metal-based liquid material thereto by a double jet while stirring the mother liquor with a solution containing no silicon-based material, or A method in which the mother liquor is externally circulated and a silicon-based liquid and a metal-based liquid are simultaneously added to a mixer provided in the external circulation path by a double jet is used. Mixing by such a method is preferable because the reaction can be performed in a state where the silicon-based material is well dispersed in the liquid.
[0080]
When a solution containing a precipitant is added, the silicon-based liquid, the metal-based liquid, and the solution containing the precipitant may be mixed according to any method and in any order. Specifically, a method in which a silicon-based liquid is used as a mother liquor, and another liquid is simultaneously added to the mother liquor by double jet while stirring the mother liquor, or a mother liquor is externally circulated to a mixer provided in an external circulation path. A method in which other liquids are simultaneously added by a double jet, or a liquid containing no silicon-based material is used as a mother liquor, and while the mother liquor is being stirred, a silicon-based liquid, a metal-based liquid, and a solution containing a precipitant are added. By triple jet, or by circulating the mother liquor externally and simultaneously adding the silicon-based liquid, the metal-based liquid, and the solution containing the precipitant to the mixer provided in the external circulation path by triple jet And the like. Mixing by such a method is preferable because the reaction can be performed in a state where the silicon-based material is well dispersed in the liquid.
[0081]
Regardless of the presence or absence of a solution containing a precipitant, these liquids may be added either on the surface of the mother liquor or in the mother liquor, and are preferably in the mother liquor from the viewpoint of more uniform mixing. Further, the stirring Reynolds number is preferably at least 1,000, preferably at least 3,000, more preferably at least 5,000. By setting the stirring Reynolds number to 1,000 or more, each liquid can be more uniformly mixed.
[0082]
After the completion of the precursor forming step, a drying step is preferably performed prior to the firing step. The drying temperature is preferably in the range of 20 to 300 ° C, more preferably 30 to 200 ° C. Examples of the method for directly drying include evaporation and spray drying for drying while granulating.
[0083]
In the drying step, before drying the precursor, it is preferable to remove insoluble salts by an existing method such as filtration and washing, membrane separation and the like, if necessary. After that, it is preferable to separate the precursor from the liquid by a method such as filtration or centrifugation.
[0084]
Next, the firing step will be described.
[0085]
In the firing step in the present invention, the precursor is fired in a state where fusion of the silicon-based material particles is controlled so as not to substantially occur, and the metal element precipitated around the silicon-based material particles is diffused and mixed into the particles. This refers to the step of obtaining a phosphor that has been made to undergo phosphorescence.
[0086]
In the precursor forming step, the metal element can be deposited with a uniform composition around the silicon-based material particles, so that the metal element can be uniformly diffused and mixed inside the particles by controlling the firing conditions. In addition, since no mechanical mixing / pulverization step is performed in the precursor forming step, the particle shape can be substantially constant depending on the shape of the silicon-based material particles used.
[0087]
Here, “the state in which the fusion of the silicon-based material particles does not substantially occur” means that at least 90% or more of the particles (fired product) obtained after the calcination have been fused with each other. Say no state.
[0088]
Fusion of silicon-based material particles is greatly related to the particle size and the firing temperature. For example, when the particle size of the silicon-based material particles is 0.01 to 0.1 μm, the firing temperature is preferably 400 to 800 ° C., and when the particle size of the silicon-based material particles is 0.1 to 0.5 μm. The firing temperature is preferably from 600 to 1000 ° C., and when the particle diameter of the silicon-based material particles is from 0.5 to 1 μm, the firing temperature is preferably from 800 to 1200 ° C.
[0089]
It is preferable to fire at least once in the range of 0.5 to 100 hours under the above temperature conditions. Thereby, the silicon-based material particles do not fuse with each other, and the metal element can be diffused and mixed into the silicon-based material particles.
[0090]
By baking under the above temperature conditions until the crystallinity reaches a predetermined degree of crystallinity, it is possible to obtain a fine particle silicate phosphor having a uniform shape, a high light emission intensity, and no light emission unevenness according to the present invention. However, from the viewpoint of improving production efficiency, it is preferable to divide the firing step into (1) a metal element diffusion and mixing step, (2) a sintering inhibitor mixing step, and (3) a crystallization step.
[0091]
(1) In the metal element diffusion and mixing step, as described above, firing is performed at a firing temperature corresponding to the particle diameter of the silicon-based material particles in a state where substantially no fusion of the silicon-based material particles occurs. This is a step of sufficiently diffusing the metal element.
[0092]
(2) The sintering inhibitor mixing step is a step of mixing the obtained powder (fired product) with a sintering inhibitor after the metal element diffusion step of (1).
[0093]
The sintering inhibitor is added in order to prevent fusion of the particles, for example, metal oxides such as aluminum oxide, silicon oxide and zirconium oxide, nitrides such as silicon nitride and aluminum nitride, and silicon carbide It is preferable to be made of one or more kinds of metal compounds which are chemically stable at high temperature, such as carbides such as tungsten carbide and tantalum carbide.
[0094]
(3) In the crystallization step, the mixture obtained in the sintering inhibitor mixing step (2) is refired to crystallize the phosphor and increase its crystallinity.
[0095]
Since the sintering inhibitor is mixed, even if firing is performed at a temperature higher than the firing temperature in the metal element diffusion step (1), fusion between particles can be prevented, and desired crystallization can be achieved in a short time. Degree of silicate phosphor can be obtained. In addition, it is preferable that the re-baking is performed at least once in a temperature range of 1000 to 1400 ° C. and 0.5 to 5 hours.
[0096]
When a sintering inhibitor is added in the metal diffusion mixing step (1), the sintering inhibitor may act to prevent the metal element from being diffused and mixed into the silicon-based material particles, which is not preferable. .
On the other hand, if the crystallization step (3) is performed without adding a sintering inhibitor, the sintering temperature is high, and the particles may fuse with each other.
[0097]
In the firing step, Zn ₂ SiO ₄ : When baking a precursor such as Mn, baking is preferably performed in an inert atmosphere. Further, an air atmosphere (or an oxygen atmosphere) and a reducing atmosphere may be combined as needed. When a reducing atmosphere is used in combination, firing at a temperature of 800 ° C. or less is preferable in order to prevent evaporation of metal elements such as zinc from the crystal. Examples of a method for obtaining a reducing atmosphere include a method of placing a lump of graphite in a boat filled with a precursor, a method of firing in a nitrogen-hydrogen atmosphere, or a rare gas / hydrogen atmosphere. These atmospheres may contain water vapor.
[0098]
After the firing step, the obtained silicate phosphor may be subjected to a treatment such as dispersion, washing with water, drying and sieving.
[0099]
The silicate phosphor produced by the above method is used for various devices such as a fluorescent lamp and a fluorescent display tube, various display devices such as a PDP and an FED, or a fluorescent paint, an ashtray, a stationery, an outdoor article, a guide plate, a guide, It can be suitably used for an article using a silicate phosphor such as a safety sign.
[0100]
Hereinafter, a plasma display panel will be described as an example of a display device using the silicate phosphor according to the present invention with reference to FIG. PDPs are roughly classified into an AC type that applies a DC voltage and a DC type that applies an AC voltage when roughly classified according to the structure and operation mode of the electrodes. FIG. 1 shows the configuration of the AC type PDP. An example of the outline is shown.
[0101]
One of the two substrates 10 and 20 shown in FIG. 1 is a front plate 10 arranged on the display side, and the other is a rear plate 20 arranged on the back side. The front plate 10 and the rear plate 20 are opposed to each other at a predetermined interval by a partition 30 provided between the substrates 10 and 20.
[0102]
First, the configuration of the front plate 10 will be described.
The front plate 10 can be formed from a material that transmits visible light, such as soda lime glass. As shown in FIG. 1, an electrode 11, a dielectric layer 12, a protective layer, and the like are provided on a surface of the front plate 10 facing the rear plate 20.
[0103]
The electrodes 11 provided on the front plate 10 include a pair of scanning electrodes 11a and sustaining electrodes 11b, and each of the electrodes 11a and 11b is formed in a strip shape. Scan electrode 11a and sustain electrode 11b are provided with a predetermined discharge gap. Plasma discharge for causing the phosphor to emit light is performed by surface discharge between the scan electrode 11a and the sustain electrode 11b.
[0104]
As shown in FIG. 2, the electrodes 11 are provided so as to continuously traverse from the end 10c to the end 10d of the front plate 10, and are regularly arranged at predetermined intervals. Each of the electrodes 11 is connected to a panel drive circuit 15 and can apply a voltage to a desired electrode 11.
[0105]
As shown in FIG. 1, a dielectric layer 12 is provided so as to cover the entire surface of front plate 10 on which these electrodes 11 are arranged. The dielectric layer 12 is made of a dielectric material, and is generally often made of a lead-based low-melting glass. In addition, the dielectric layer 12 may be formed of bismuth-based low-melting glass or a laminate of lead-based low-melting glass and bismuth-based low-melting glass.
[0106]
The surface of the dielectric layer 12 is entirely covered by the protective layer 13. The protective layer 13 is preferably a thin layer made of magnesium oxide (MgO).
[0107]
Next, the configuration of the rear plate 20 will be described.
The back plate 20 is formed to have substantially the same size as the front plate 10, and can be made of soda lime glass or the like, similarly to the front plate 10. A plurality of data electrodes 21, a dielectric layer 22, partition walls 30, and the like are provided on a surface of the back plate 20 facing the front plate 10.
[0108]
The data electrodes 21 are formed in a band shape similarly to the electrodes 11, and are provided at predetermined intervals. The partition 30 is provided on both sides of the data electrode 21. As shown in FIG. 2, the data electrode 21 is divided at a central portion 24 of the back plate 20, and each is connected to the panel drive circuits 25a and 25b. By the panel drive circuit 25, a voltage can be applied to a desired electrode 21.
[0109]
As shown in FIG. 1, the entire surface of the back plate 20 on which the data electrodes 21 are arranged is covered with a dielectric layer 22. Like the dielectric layer 12, the dielectric layer 22 can be made of lead-based low-melting glass, bismuth-based low-melting glass, or a laminate of lead-based low-melting glass and bismuth-based low-melting glass. In addition, these dielectric materials have TiO ₂ It is preferable to mix the particles so that they also function as a visible light reflecting layer. When the dielectric layer 22 also functions as a visible light reflecting layer in this way, even if light is emitted from the phosphor layer 35 to the back plate 20 side, it is reflected to the front plate 10 side and transmitted through the front plate 10. More light to be emitted, and the luminance can be improved.
[0110]
A partition 30 is provided on the upper surface of the dielectric layer 22 so as to protrude from the rear plate 20 to the front plate 10. The partition 30 divides a space between the substrates 10 and 20 into a plurality of predetermined shapes, and forms the discharge cells 31 as described above. The partition 30 is formed from a dielectric material such as a glass material.
[0111]
The discharge cell 31 is a discharge space surrounded by the partition wall 30 and the substrates 10 and 20 as described above, and the side surface 30a of the partition wall 30 facing the inside of the discharge cell 31 and the bottom surface 31a of the discharge cell have red ( The phosphor layers 35 that emit light of any of R), green (G), and blue (B) are regularly provided in the order of R, G, and B. A discharge gas mainly composed of a rare gas is sealed in the discharge cell 31. As the discharge gas, it is particularly preferable to use a mixed gas in which Ne is used as a main discharge gas and Xe which generates ultraviolet rays by discharge is mixed with the main discharge gas. The pressure at which the mixed gas is charged is not particularly limited, but is preferably, for example, about 66.7 mPa.
[0112]
The discharge cell 31 shown in FIG. 1 is of a so-called stripe type, in which partition walls 30 are provided on both sides of the data electrode 21 and formed in parallel grooves by the partition walls 30.
[0113]
Here, the arrangement of the discharge cells 31 and the electrodes 11 and 21 will be described.
As shown in FIG. 2, the electrodes 11 and the data electrodes 21 are orthogonal to each other in a plan view and are in a matrix. In one discharge cell 31, a number of intersections between the electrode 11 and the data electrode 21 are provided. Discharge can be selectively performed at the intersection of the electrode 11 and the data electrode 21, thereby enabling desired information to be displayed. Hereinafter, the space of a cell obtained by dividing the volume of one cell by the number of intersections of the electrodes in the cell is referred to as a minimum light emitting unit. In the PDP 1, one pixel is formed by three minimum light emission units of R, G, and B adjacent to each other.
[0114]
In the present invention, the phosphor layer of at least one of R, G, and B contains the silicate phosphor according to the present invention. In forming the phosphor layer, various conventionally known methods can be used. For example, the bottom surface (on the address electrode 21) and the side surfaces of the discharge cells 31 partitioned by the partition walls 30 are coated or filled with a phosphor prepared in a paste form, and the phosphor paste is dried or fired to form an organic substance in the paste. The phosphor layer can be formed by removing the components.
[0115]
When the phosphor is adjusted to a paste, a solvent, a binder resin, a dispersant, and the like may be appropriately mixed with the phosphor.
[0116]
As a method of applying or filling the phosphor paste between the partition walls, various methods such as a screen printing method, a photoresist film method, and an ink jet method can be used. Above all, in the rib structure having a high definition, the pitch of the partition walls is also fine, and it is particularly preferable to apply an ink jet method as a coating method for easily and accurately forming the fluorescent layer uniformly at low cost between the partition walls.
[0117]
The display such as PDP1 according to the present invention can improve the panel brightness by forming a phosphor layer using the silicate phosphor obtained by the manufacturing method of the present invention. In particular, when a silicate phosphor that emits green light is used, the luminous intensity of a green cell having high visibility can be improved, so that white luminance is improved.
[0118]
Furthermore, since the silicate phosphor according to the present invention has a small particle size and a substantially uniform shape, it is necessary to apply the silicate phosphor efficiently in a minute discharge space such as the discharge cell 31G of the PDP 1. Becomes possible. Therefore, the luminance of a display or the like can be further improved.
[0119]
【Example】
Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
[0120]
(Example 1)
1. Manufacture of phosphor
(1) Production of silicate phosphor 1-1
First, liquid A was prepared by mixing 11.27 g of silicon dioxide (Snowtex MP-4540M, Nissan Chemical Industries, Ltd., 40 wt%, particle size 0.5 μm) with 516.29 g of pure water. At the same time, a solution B was prepared by dissolving 42.39 g of zinc nitrate hexahydrate and 2.15 g of manganese nitrate hexahydrate in 51.84 g of pure water. Further, 21.90 g of aqueous ammonia (28%) was mixed with 50.67 g of pure water to prepare a liquid C.
[0121]
FIG. 4 shows a scanning electron microscope (SEM) photograph of the used silicon dioxide. As is clear from FIG. 4, it can be seen that the silicon dioxide particles have a spherical shape, and their particle diameters and particle shapes are uniform.
[0122]
Next, using the reaction apparatus 100 shown in FIG. 3, while stirring the solution A, the solution B and the solution C were simultaneously added to the surface of the solution A by a double jet using a roller pump 110 at an addition speed of 10 cc / min. . After the completion of the addition of the liquids B and C, the solid-liquid separation was performed by suction filtration, and the solids were sufficiently washed with pure water. Next, drying was performed at 40 ° C. for 50 hours to obtain a dried precursor.
[0123]
Next, the obtained precursor was baked at 900 ° C. for 50 hours in an atmosphere of 100% nitrogen to obtain a silicate phosphor 1-1.
[0124]
(2) Production of silicate phosphor 1-2
Silicate fluorescence of the above (1) except that silicon dioxide was changed to Nissan Chemical Industries Co., Ltd. Snowtex MP-2040 (40 wt%, particle size 0.2 μm), and firing of the precursor was performed at 850 ° C. for 70 hours. A silicate phosphor 1-2 was obtained in the same manner as in the body 1-1.
[0125]
(3) Production of silicate phosphor 1-3
The silicate fluorescence of the above (1) except that the silicon dioxide was changed to Snowtex O-40 (40 wt%, particle size 0.03 μm) manufactured by Nissan Chemical Industries, Ltd., and the precursor was fired at 750 ° C. for 90 hours. A silicate phosphor 1-4 was obtained in the same manner as in the body 1-1.
[0126]
(4) Production of Comparative Example 1
A phosphor (Comparative Example 1) was obtained in the same manner as in the above (1), except that the precursor was fired at 1200 ° C. for 3 hours.
[0127]
2. Evaluation
The silicate phosphors 1-1 to 1-3 obtained above and Comparative Example 1 were evaluated for (1) emission intensity and (2) particle shape.
[0128]
(1) Emission intensity evaluation
The silicate phosphors 1-1 to 1-3 and Comparative Example 1 were irradiated with ultraviolet rays using an excimer 146 nm lamp (manufactured by Ushio Inc.) in vacuum chambers of 0.1 to 1.5 Pa, respectively, to produce silicic acid. Green light was emitted from the salt phosphor. Next, the intensity of the obtained green light was measured using a detector (MCPD-3000 (manufactured by Otsuka Electronics Co., Ltd.)). Then, the peak intensity of the light emission was determined as a relative value with Comparative Example 1 being 100. Table 1 shows the obtained results.
[Table 1]

[0129]
From Table 1, as in the firing step according to the present invention, a precursor containing a metal element in a uniform composition around the silicon-based material particles, by firing at a temperature at which the silicon-based material particles do not fuse to each other, The result was obtained that the emission intensity of the silicate phosphor was increased by uniformly diffusing the metal element into the particles and crystallizing the same.
[0130]
(2) Evaluation of particle shape
Next, scanning electron microscope (SEM) photographs of the silicate phosphors 1-1 to 1-3 and Comparative Example 1 are shown in FIGS.
Table 2 shows the average particle size obtained by randomly selecting 100 phosphor particles from the scanning electron micrograph.
[Table 2]

[0131]
As shown in FIG. 8, the phosphor obtained by the manufacturing method of Comparative Example 1 had an irregular shape in which particles were fused to each other, and the particle shape between the particles was uneven. The shape was also greatly different from the used silicon dioxide (FIG. 4), the average particle size increased from 0.5 μm to 1.58 μm, and the particle size distribution also varied.
[0132]
On the other hand, as shown in FIGS. 5 to 7, the phosphors 1-1 to 1-3 had a uniform particle shape, and could obtain substantially the same shape as the silicon dioxide used.
Also, the average particle size was substantially the same as the average particle size of the silicon dioxide used as the raw material, and there was little variation in the particle size distribution. Even when 0.03 μm of silicon dioxide is used as in the case of phosphor 1-3, as shown in FIG. 7, it is possible to obtain a particle having a uniform grain shape and particles not fused to each other. Was.
[0133]
(Example 2)
1. Manufacture of phosphor
(1) Silicate phosphor 2-1
The dried precursor obtained in the same manner as the silicate phosphor 1-1 is first fired at 950 ° C. for 3 hours in an atmosphere of 100% nitrogen to diffuse and mix other metal elements into silicon dioxide. I let it. Next, aluminum oxide C (a sintering inhibitor, manufactured by Aerosil) was mixed at a ratio of 0.1 wt% to the obtained powder. Further, the mixture was refired at 1200 ° C. for 3 hours in an atmosphere of 100% nitrogen to obtain a silicate phosphor 2-1.
[0134]
(2) Production of silicate phosphor 2-2
The dried precursor obtained in the same manner as the silicate phosphor 1-2 is first fired at 900 ° C. for 3 hours in an atmosphere of 100% nitrogen to diffuse and mix other metal elements into silicon dioxide. I let it. Thereafter, recalcination was performed in the same manner as the silicate phosphor 2-1 to obtain a silicate phosphor 2-2.
[0135]
(3) Production of silicate phosphor 2-3
The dried precursor obtained in the same manner as the silicate phosphor 1-3 is first fired at 800 ° C. for 3 hours in an atmosphere of 100% nitrogen to diffuse and mix other metal elements into silicon dioxide. I let it. Thereafter, recalcination was performed in the same manner as the silicate phosphor 2-1 to obtain a silicate phosphor 2-3.
[0136]
(4) Production of Comparative Example 2
The dried precursor obtained in the same manner as the silicate phosphor 1-1 is first fired at 950 ° C. for 3 hours in an atmosphere of 100% nitrogen to diffuse and mix other metal elements into silicon dioxide. I let it. Next, the obtained powder was refired at 1200 ° C. for 3 hours in an atmosphere of 100% nitrogen to obtain Comparative Example 2.
[0137]
2. Evaluation
The silicate phosphors 2-1 to 2-3 obtained above and Comparative Example 2 were evaluated for (1) emission intensity and (2) particle shape.
[0138]
(1) Emission intensity evaluation
The silicate phosphors 2-1 to 2-3 and Comparative Example 2 were irradiated with ultraviolet light using an excimer 146 nm lamp (manufactured by Ushio Inc.) in a vacuum chamber of 0.1 to 1.5 Pa, respectively. Green light was emitted from the salt phosphor. Next, the intensity of the obtained green light was measured using a detector (MCPD-3000 (manufactured by Otsuka Electronics Co., Ltd.)). Then, the peak intensity of the light emission was obtained as a relative value with Comparative Example 2 being 100. Table 3 shows the obtained results.
[Table 3]

[0139]
As shown in Table 3, when compared with the case of refiring without performing the sintering inhibitor mixing step as in Comparative Example 2, the sintering prevention was performed as shown in phosphors 2-1 to 2-3. By performing refiring (crystallization step) after performing the agent mixing step, the result that the emission intensity of the silicate phosphor was increased was obtained.
[0140]
(2) Evaluation of particle shape
Next, the particle shapes of the silicate phosphors 2-1 to 2-3 and the silicate phosphors obtained in Comparative Example 2 were confirmed with a scanning electron microscope (SEM). Comparative Example 2 shows a non-uniform shape in which the particles are fused to each other, whereas the silicate phosphors 2-1 to 2-3 have a uniform particle shape, and the used silicon dioxide (silicon-based) Material) It was found that a silicate phosphor having substantially the same shape as the particles was obtained. The particle diameters of the silicate phosphors 2-1 to 2-3 were substantially the same as those of the silicon dioxide used as the raw material, but the average particle diameter of Comparative Example 2 was increased. The distribution was also broad.
[0141]
(Example 3)
The silicate phosphor 1-1 manufactured in Example 1 and the phosphor of Comparative Example 1 were evaluated for uniformity in the distribution of the composition of the constituent elements in the particles.
The evaluation was performed by quantifying the internal composition of particles by analyzing a characteristic X-ray generated from a sample when irradiated with an electron beam using a transmission electron microscope (TEM).
[0142]
First, a sample of each silicate phosphor was cut out continuously as a 50-nm section. Next, the section was placed on a mesh for observation with an electron microscope, carbon was deposited, and characteristic X-rays were measured using a transmission electron microscope. From the analysis of the obtained characteristic X, particles in which the difference in the content of Zn, Mn, and Si in each intercept is 20% or less of the theoretical value of the content of each element are regarded as particles having a microscopically uniform composition distribution. did.
The same measurement was performed for 100 silicate phosphors, and the ratio of particles whose composition distribution was microscopically uniform was calculated. Table 4 shows the measurement results.
[Table 4]

[0143]
As shown in Table 4, it can be seen that the distribution of the composition of the constituent elements in the particles of the phosphor 1-1 according to the present invention is extremely uniform.
[0144]
(Example 4)
The silicate phosphor 1-1 manufactured in Example 1 and the phosphor of Comparative Example 1 were evaluated for the content of the constituent elements contained in the particles.
First, using a secondary ion mass spectrometer (SIMS) apparatus, the composition of each particle was quantified using a relative sensitivity coefficient. Next, the variation coefficient between the particles of the content of the constituent elements contained in the particles was determined by measuring 100 particles.
The coefficient of variation was determined by multiplying the value obtained by dividing the standard deviation of the composition content at the time of measuring the content of the constituent elements contained in each particle by the average content, by 100. Table 5 shows the measurement results.
[Table 5]

[0145]
As shown in Table 5, it can be seen that there is little variation between particles in the content of the constituent elements contained in the particles of the phosphor 1-1 according to the present invention.
[0146]
(Example 5)
Phosphors 1-1 to 1-3 produced in Example 1 and Comparative Example 1, a blue phosphor B and a red phosphor R were produced by the method described below, and a phosphor layer containing these phosphors was prepared. The provided PDP was manufactured and evaluated for white luminance.
The phosphors 1-1 to 1-3 and Comparative Example 1 each have a composition formula of Zn ₂ SiO ₄ : A green phosphor represented by Mn.
[0147]
1. Manufacture of phosphor
(1) Production of blue phosphor B
Barium carbonate (BaCO ₃ ), Magnesium carbonate (MgCO ₃ ), Aluminum oxide (α-Al ₂ O ₃ ) Is mixed in a molar ratio of 1: 1: 1: 5. Next, a predetermined amount of europium oxide (Eu) was added to the mixture. ₂ O ₃ ) Is added. Then, an appropriate amount of flux (AlF ₂ , BaCl ₂ ), And calcined at 1600 ° C. for 3 hours in a reducing atmosphere of 95% nitrogen and 5% hydrogen to obtain a phosphor. The obtained phosphor was classified, and one having an average particle size of 1.5 μm was designated as blue phosphor B.
[0148]
(2) Production of red phosphor R
Yttrium oxide (Y ₂ O ₃ ) And gadolinium oxide (Gd ₂ O ₃ ) And boric acid (H ₃ BO ₃ ) Are blended so that the atomic ratio of Y, Gd, and B is 0.60: 0.35: 1.0. Next, a predetermined amount of europium oxide (Eu) was added to the mixture. ₂ O ₃ ) Is added. The mixture was mixed with an appropriate amount of flux in a ball mill and fired at 1400 ° C. for 3 hours in an air atmosphere to obtain a silicate phosphor. The obtained phosphor was classified, and one having an average particle size of 1.5 μm was designated as red phosphor R.
[0149]
2. Preparation of phosphor coating solution
Using each of the blue phosphor B and the red phosphor R obtained by the above method, and each of the phosphors 1-1 to 1-3 and Comparative Example 1, one of ethyl cellulose, polyoxyethylene alkyl ether, terpineol and pentanediol was used. : 1 mixture solution, phosphor coating solutions B, R, G-1 to G-3 and Comparative Example G were prepared.
[0150]
3. Manufacture of PDP
(1) Production of PDP1
Using the blue phosphor coating solution B, red phosphor coating solution R, and green phosphor coating solution G-1 prepared above, a 42-inch PDP shown in FIG. 1 was produced as follows.
First, scan electrodes 11a and sustain electrodes 11b were formed on a glass substrate serving as front plate 10 by an inkjet method using a nozzle having a diameter of 50 μm. At this time, while keeping the distance between the nozzle tip and the front plate at 1 mm, the nozzle tip scans a predetermined position on the front plate 10 while discharging the electrode material ink to form a scanning electrode 11a having an electrode width of 60 μm. The sustain electrodes 11b were respectively formed.
[0151]
Next, a low-melting glass is printed on the front plate 10 via the electrodes 11 and is fired at 500 to 600 ° C. to form a dielectric layer 12. The protective film 13 was formed by vapor deposition.
[0152]
On the other hand, a data electrode 21 was formed on a glass substrate serving as a back plate 20. Similarly to the above, a data electrode 21 having a width of 60 μm was formed using a nozzle having a diameter of 50 μm while maintaining a distance of 1 mm from the back plate 20 and scanning a predetermined position. Next, stripe-shaped barrier ribs 30 were formed using low-melting glass so as to be located on both sides of the data electrode. The interval (pitch) between the partitions 30 was 0.36 mm, and the height of the partitions 30 was 0.15 mm.
[0153]
Further, the bottom surface 31a facing the inside of the cell 31 partitioned by the partition wall 30 and the side surface 30a of the partition wall 30 have the above-mentioned 2. The phosphor coating solutions B, R, and G-1 prepared in the above were applied to adjacent cells one by one in a regular order.
[0154]
Then, the front plate 10 on which the electrodes 11, 21 and the like are arranged and the back plate 20 are aligned so that the respective electrode arrangement surfaces face each other, and the partition wall 30 keeps a gap of about 1 mm. The periphery was sealed with a seal glass. A gas mixture of xenon (Xe), which generates ultraviolet rays by discharge, and neon (Ne), a main discharge gas, was sealed between the substrates 10 and 20, and hermetically sealed. The mixing volume ratio of xenon and neon was 1: 9, and the filling pressure was 66.7 mPa. Thereafter, aging was performed to obtain PDP1.
[0155]
(2) Production of PDP2
A PDP was manufactured in the same manner as PDP1 except that G-2 was used as the green phosphor coating liquid, and was used as PDP2.
[0156]
(3) Production of PDP3
A PDP was produced in the same manner as PDP1 except that G-3 was used as the green phosphor coating liquid, and was used as PDP3.
[0157]
(4) Production of Comparative Example 3
A PDP was manufactured in the same manner as PDP1 except that Comparative Example G was used as a green phosphor coating liquid, and this was used as a comparative example.
[0158]
4. Evaluation
For each of the PDPs 1 to 3 and the comparative examples obtained above, the luminance was measured when the panel was driven at a frequency of 30 KHz with the discharge sustaining voltage when the entire panel was lit, and the panel luminance of P-1 was 100%. And expressed as relative values. Table 6 shows the evaluation results.
[Table 6]

[0159]
Table 6 shows that the green phosphor layer formed using the phosphors 1-1 to 1-3 according to the present application is compared with the case where the green phosphor layer is formed using the phosphor manufactured according to Comparative Example 1. However, it was found that the panel luminance of the PDP also improved.
[0160]
Further, when visually confirmed, PDPs 1 to 3 were able to display images beautifully without unevenness in light emission, as compared with the panel of Comparative Example 3.
[0161]
【The invention's effect】
According to the first aspect of the present invention, since the particles of the silicate phosphor are not in an irregular shape fused to each other, mechanical pulverization for forming the phosphor particles into a certain size and a certain shape is performed. There is no need to perform any processing or the like, and a decrease in light emission intensity due to crystal defects can be prevented. Furthermore, since the particles are extremely fine particles and the shapes are uniform among the particles, the emission intensity of the cell can be improved when used in the phosphor layer of the PDP.
[0162]
According to the invention as set forth in claim 2, since the phosphor is an extremely fine particle, the coefficient of variation of the particle size distribution is small, and the size and the shape are substantially the same between the particles, the phosphor is used for any purpose. Also, it is possible to emit light with high brightness and without unevenness. Further, the phosphor can be densely filled in the phosphor layer provided in the cell of the PDP, and the emission intensity of the cell can be improved.
[0163]
According to the third aspect of the present invention, the particles having a uniform composition distribution of the constituent elements in the particles occupy 50% or more in the number of particles, so that the light emission characteristics of the particles become uniform. Therefore, by forming the phosphor layer of the cell of the PDP with this phosphor, it is possible to obtain an excellent one with no light emission unevenness.
[0164]
According to the fourth aspect of the present invention, since the variation coefficient of the inter-particle distribution of the content of each constituent element in the particle is 50% or less, there is no variation in the amount of the constituent element contained in each particle, and the unevenness is reduced. No light emission can be performed.
[0165]
According to the invention as set forth in claim 5, in the precursor forming step, a precursor containing a metal element capable of constituting a silicate phosphor in a uniform composition is formed around the silicon-based material particles by firing. Since the metal element is diffused and mixed into the silicon-based material particles in the firing step, a phosphor having a uniform composition can be obtained. In addition, since the fusion of the silicon-based material particles does not substantially occur when the precursor is fired, it is possible to prevent the resulting phosphor particles from being fused to each other and becoming an irregular shape. .
[0166]
According to the invention as set forth in claim 6, efficiency in producing a silicate phosphor can be improved.
[0167]
According to the invention of claim 7, since the precursor is formed by the liquid phase method, the silicon-based material and the metal element other than silicon constituting the silicate phosphor are uniformly mixed in the liquid. By adjusting the reaction conditions, the constituent elements can be uniformly diffused and distributed in the particles, and a phosphor having a uniform content of the constituent elements can be obtained.
[0168]
According to the invention of claim 8, the silicate phosphor has the same effect as any one of claims 1 to 4.
[0169]
According to the ninth aspect of the present invention, the PDP has the phosphor layer containing the silicate phosphor according to any one of the first to fifth and ninth aspects. Phosphors can be densely packed, thereby improving the light emission intensity of the cell.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a plasma display panel according to an example of the present invention.
FIG. 2 is a schematic plan view showing an arrangement of electrodes provided on the plasma display panel shown in FIG.
FIG. 3 is a schematic view showing an example of a reaction apparatus used in the method for producing a phosphor according to the present invention.
FIG. 4 is a scanning electron micrograph showing silicon dioxide used as a raw material in Example 1.
FIG. 5 is a scanning electron micrograph of a phosphor 1-1 manufactured in Example 1.
FIG. 6 is a scanning electron micrograph of a phosphor 1-2 produced in Example 1.
FIG. 7 is a scanning electron micrograph of a phosphor 1-3 produced in Example 1.
FIG. 8 is a scanning electron micrograph showing the phosphor of Comparative Example 1.
[Explanation of symbols]
1 Plasma display panel
35 phosphor layer

Claims (9)

A silicate phosphor in which a metal element capable of constituting a silicate phosphor is diffused and mixed by firing on a silicon-based material constituting a mother nucleus of the silicate phosphor,
A silicate phosphor having an average particle size of 0.01 to 1 [mu] m, and the particles are not fused to each other. A silicate phosphor in which a metal element capable of constituting a silicate phosphor is diffused and mixed by firing on a silicon-based material constituting a mother nucleus of the silicate phosphor,
A silicate phosphor having an average particle diameter of 0.01 to 1 μm, a coefficient of variation of particle diameter distribution of 40% or less, and each particle having substantially the same shape. The silicate phosphor according to claim 1 or 2,
A silicate phosphor characterized in that particles having a uniform distribution of the composition of constituent elements in the particles are 50% or more in number of particles. The silicate phosphor according to any one of claims 1 to 3,
A silicate phosphor characterized in that the coefficient of variation of the inter-particle distribution of the content of the constituent elements in the particles is 50% or less. Around the silicon-based material particles serving as the mother nucleus of the silicate phosphor, a precursor forming step of forming a precursor containing a metal element capable of constituting the silicate phosphor by a uniform composition by firing.
Firing in a state where the fusion of the silicon-based material particles does not substantially occur, to obtain a silicate phosphor in which the metal element is diffused and mixed inside the silicon-based material particles,
A method for producing a silicate phosphor, comprising: The method for producing a silicate phosphor according to claim 5,
The firing step includes:
Baking the precursor in a state where the fusion of the silicon-based material particles substantially does not occur, a metal element diffusion mixing step of diffusing and mixing the metal element inside the silicon-based material particles,
A sintering inhibitor mixing step of mixing a sintering inhibitor into the fired product obtained in the metal element diffusion mixing step,
A crystallization step of obtaining a crystallized silicate phosphor by refiring the mixture obtained in the sintering inhibitor mixing step,
A method for producing a silicate phosphor, comprising: The method for producing a silicate phosphor according to claim 5 or 6,
The method for producing a silicate phosphor, wherein the precursor forming step is performed by a liquid phase method. A silicate phosphor obtained by the method for producing a silicate phosphor according to claim 5. A plasma display panel comprising a phosphor layer containing the silicate phosphor according to any one of claims 1 to 4.

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