JP5153014B2

JP5153014B2 - Green phosphor

Info

Publication number: JP5153014B2
Application number: JP2010209992A
Authority: JP
Inventors: 正樹入江
Original assignee: Covalent Materials Corp
Current assignee: Coorstek KK
Priority date: 2010-09-17
Filing date: 2010-09-17
Publication date: 2013-02-27
Anticipated expiration: 2030-09-17
Also published as: JP2012062444A

Abstract

<P>PROBLEM TO BE SOLVED: To provide a green phosphor using LuAG:Ce as a material and improved in properties such as luminous intensity and life as a green phosphor. <P>SOLUTION: The green phosphor is constituted of inorganic materials having a first phase 3 composed of Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>and a second phase 5 composed of LuAG containing Ce, wherein the content of the second phase 5 is ≥25 and ≤95 vol.% in terms of volume ratio in the whole phase containing the first and second phases; the content of Ce in LuAG is ≥0.003 and ≤0.03 in terms of atomic ratio (Ce/Lu) to Lu; or the content of the second phase 5 is ≥80 and ≤95 vol.% in terms of volume ratio, and the content of Ce is ≥0.001 and ≤0.03 in terms of atomic ratio (Ce/Lu) to Lu. <P>COPYRIGHT: (C)2012,JPO&INPIT

Description

本発明は、緑色蛍光体に関し、特に、発光強度や寿命等の特性を向上させることができる緑色蛍光体に関する。 The present invention relates to a green phosphor, and more particularly to a green phosphor capable of improving characteristics such as emission intensity and life.

緑色蛍光体は、ＦＥＤ（Field Emitter Display：電界放射型ディスプレイ）、ＬＣＤ（Liquid Crystal Display：液晶ディスプレイ）やＰＤＰ（Plasma
Display Panel:プラズマディスプレイパネル）などのディスプレイ用として、青色ＬＥＤ（Light
Emitting Diode：発光ダイオード）を光源として用いた照明用として、また、プロジェクタに用いる光学スペクトルの緑色領域用として、様々な分野・用途に使用されている。 Green phosphors are FED (Field Emitter Display), LCD (Liquid Crystal Display) and PDP (Plasma).
Blue LED (Light LED) for displays such as Display Panel
Emitting Diode (Light Emitting Diode) is used in various fields and applications for illumination using a light source and for a green region of an optical spectrum used for a projector.

近年、緑色蛍光体は、発光強度や寿命等に優れた特性を有することが要求されており、様々な改良が行われている。
特許文献１では、波長が３５０〜５００ｎｍの光により励起されて発光強度が高い良好な緑色発光を示すものとして、組成式：ＡＴｂ_ｘＬｎ_{（１−ｘ）}Ｍ_２Ｏ_８（式中、ＡはＬｉ、Ｎａ、Ｋ及びＡｇから選ばれる少なくとも１種、ＬｎはＹを含む希土類元素（Ｔｂを除く）から選ばれる少なくとも１種、ＭはＭｏ及びＷから選ばれる少なくとも１種、ｘは０．４≦ｘ≦１を満たす整数）で表される緑色蛍光体が開示されている。また、特許文献２には、Ｌａ、Ｍｇ、Ａｌと、Ｙ又はＣｅのいずれかを必ず含み、更に、Ｔｂ、Ｍｎ、Ｚｎを任意で含み、Ｌａ、Ｍｇ、Ａｌが母材であり、他の元素が発光中心である緑色蛍光体が開示されている。 In recent years, green phosphors are required to have excellent characteristics such as emission intensity and lifetime, and various improvements have been made.
In Patent Document 1, a composition formula: ATb _x Ln _(1-x) M ₂ O ₈ (wherein A represents a good green light emission that is excited by light having a wavelength of 350 to 500 nm and has high emission intensity ₎ At least one selected from Li, Na, K and Ag, Ln is at least one selected from rare earth elements including Y (excluding Tb), M is at least one selected from Mo and W, and x is 0.4 An integer satisfying ≦ x ≦ 1 is disclosed. Patent Document 2 always includes La, Mg, Al, and any one of Y or Ce, further includes Tb, Mn, and Zn, La, Mg, and Al are base materials. A green phosphor whose element is the emission center is disclosed.

しかしながら、特許文献１に記載の緑色蛍光体においては、1価のＡサイト（ＡはＬｉ、Ｎａ、Ｋ）を３価のＴｂ^３＋イオンで置換するため、結晶構造に大きな歪みが生じやすい。その結果、結晶構造的に不安定であるため、発光強度が低下するという問題が見られた。また、発光イオンとしてＴｂ^３＋イオンを高濃度で含有しており、更に、Ｔｂ^３＋イオンの増感剤としてＹ^３＋イオン、Ｄｙ^３＋イオン、Ｌａ^３＋イオン、Ｇｄ^３＋イオン又はＬｕ^３＋イオンを含有しているため、これらが蛍光体内で析出する場合があり、発光強度等の向上には限界があるものであった。この他、特許文献１に記載の緑色蛍光体は、樹脂、ゴム等に分散させて蛍光体層として使用するものであり、樹脂の劣化による発光ダイオード等のデバイスの発光強度の劣化や短寿命化を抑制することが難しいものであった。
更に、特許文献２に記載の緑色蛍光体は、類似サイトを２価イオン（Ｍｇ^２＋、Ｍｎ^２＋、Ｚｎ^２＋）および３価イオン（Ｌａ^３＋、Ｔｂ^３＋）で構成しているため、結晶構造的に不安定であり、歪みが生じたり、異相が析出する場合があり、発光強度等の向上には限界があるものであった。 However, in the green phosphor described in Patent Document 1, since monovalent A sites (A is Li, Na, K) are substituted with trivalent Tb ³⁺ ions, large distortion is likely to occur in the crystal structure. As a result, there was a problem that the emission intensity was lowered because the crystal structure was unstable. Further, it contains Tb ³⁺ ions at a high concentration as luminescent ions, and further contains Y ³⁺ ions, Dy ³⁺ ions, La ³⁺ ions, Gd ³⁺ ions, or Lu ³⁺ ions as sensitizers for Tb ³⁺ ions. Therefore, these may be precipitated in the phosphor, and there is a limit to improving the emission intensity. In addition, the green phosphor described in Patent Document 1 is used as a phosphor layer by being dispersed in a resin, rubber or the like, and the emission intensity of a device such as a light emitting diode is deteriorated or the life is shortened due to the deterioration of the resin. It was difficult to suppress.
Further, since the green phosphor described in Patent Document 2 is composed of a divalent ion (Mg ²⁺ , Mn ²⁺ , Zn ²⁺ ) and a trivalent ion (La ³⁺ , Tb ³⁺ ) in the similar structure, Instability, distortion may occur, or a heterogeneous phase may precipitate, and there is a limit to improvement in emission intensity and the like.

一方、特許文献３には、青色又は紫外光を緑色光に変換させるためにＬｕＡＧ：Ｃｅを用いた有色及び白色光を生成する照明装置が開示されている。
更に、特許文献４には、ドープされたＹＡＧタイプの蛍光体を有する多結晶セラミック構造の蛍光体であって、前記蛍光体が、非発光多結晶アルミナを有するセラミックマトリックスに埋め込まれ、前記セラミックマトリックスが、８０乃至９９．９９ｖｏｌ．％のアルミナと、０．０１乃至２０ｖｏｌ．％の蛍光体とを有し、前記蛍光体が、（Ｌｕ１−ｘ−ｙ−ａ−ｂＹｘＧｄｙ）３（Ａｌ１−ｚＧａＺ）５Ｏ１２：ＣｅａＰｒｂの組成を持ち、０＜ｘ≦１、０≦ｙ＜１、０≦ｚ≦０．１、０≦ａ≦０．２、０≦ｂ≦０．１且つａ＋ｂ＞０であるドープされたＹＡＧである多結晶セラミックス構造の蛍光体が開示されている。 On the other hand, Patent Document 3 discloses an illumination device that generates colored and white light using LuAG: Ce to convert blue or ultraviolet light into green light.
Further, Patent Document 4 discloses a phosphor having a polycrystalline ceramic structure having a doped YAG type phosphor, wherein the phosphor is embedded in a ceramic matrix having non-light emitting polycrystalline alumina. 80 to 99.99 vol. % Alumina, 0.01 to 20 vol. % Phosphor, and the phosphor has a composition of (Lu1-x-y-a-bYxGdy) 3 (Al1-zGaZ) 5O12: CeaPrb, and 0 <x ≦ 1, 0 ≦ y <1 , 0 ≦ z ≦ 0.1, 0 ≦ a ≦ 0.2, 0 ≦ b ≦ 0.1 and a + b> 0, a phosphor with a polycrystalline ceramic structure is disclosed.

特開２００５−６８４１２号公報JP-A-2005-68412 特開２００５−８９６９２号公報JP 2005-89692 A 特表２００９−５３９２１９号公報Special table 2009-539219 特表２００８−５３３２７０号公報Special table 2008-533270 gazette

しかしながら、特許文献３には緑色光の変換材料としてＬｕＡＧ：Ｃｅを用いるという点、特許文献４には蛍光体の例として、Ｌｕ_３Ａｌ_５Ｏ_１２：Ｃｅ^３＋を用いるという点が開示されているに過ぎず、ＬｕＡＧ：Ｃｅを素材とした緑色蛍光体として発光強度や寿命等の特性を向上させるには更なる改良が必要であった。 However, Patent Document 3 discloses that LuAG: Ce is used as a green light conversion material, and Patent Document 4 discloses that Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ is used as an example of a phosphor. However, as a green phosphor made of LuAG: Ce, further improvement is required to improve characteristics such as emission intensity and lifetime.

本発明は、上述の事情に鑑みてなされたものであり、ＬｕＡＧ：Ｃｅを素材とした緑色蛍光体として発光強度や寿命等の特性を向上させることができる緑色蛍光体を提供することを目的とする。 This invention is made | formed in view of the above-mentioned situation, and it aims at providing the green fluorescent substance which can improve characteristics, such as emitted light intensity and a lifetime, as a green fluorescent substance which used LuAG: Ce as a raw material. To do.

本発明に係る緑色蛍光体は、Ａｌ₂Ｏ₃からなる第１相と、Ｃｅを含有するＬｕＡＧからなる第２相とを有する無機材料で構成された緑色蛍光焼結体であって、前記第２相の含有量は、前記第１及び第２相を含む相全体における体積比で２５ｖｏｌ％以上９５ｖｏｌ％以下であり、かつ、前記ＬｕＡＧ中のＣｅの含有量は、Ｌｕに対する原子比（Ｃｅ／Ｌｕ）で０．００３以上０．０３以下であることを特徴とする。 The green phosphor according to the present invention is a green phosphor sintered body composed of an inorganic material having a first phase made of Al ₂ O ₃ and a second phase made of LuAG containing Ce. The content of the two phases is 25 vol% or more and 95 vol% or less in the volume ratio in the entire phase including the first and second phases, and the content of Ce in the LuAG is an atomic ratio (Ce / Lu) is 0.003 or more and 0.03 or less.

また、本発明に係る緑色蛍光体は、Ａｌ₂Ｏ₃からなる第１相と、Ｃｅを含有するＬｕＡＧからなる第２相とを有する無機材料で構成された緑色蛍光焼結体であって、前記第２相の含有量は、前記第１及び第２相を含む相全体における体積比で８０ｖｏｌ％以上９５ｖｏｌ％以下であり、かつ、前記ＬｕＡＧ中のＣｅの含有量は、Ｌｕに対する原子比（Ｃｅ／Ｌｕ）で０．００１以上０．０３以下であることを特徴とする。 The green phosphor according to the present invention is a green phosphor sintered body composed of an inorganic material having a first phase made of Al ₂ O ₃ and a second phase made of LuAG containing Ce, The content of the second phase is 80 vol% or more and 95 vol% or less by volume ratio in the whole phase including the first and second phases, and the content of Ce in the LuAG is an atomic ratio with respect to Lu ( Ce / Lu) is 0.001 or more and 0.03 or less.

前記緑色蛍光体の光出射方向に平行する任意の断面で切ったときの表面において、前記光出射方向と平行する方向に任意の複数の平行直線を引いた時に、すべての平行直線上に前記第２相が接触している、又は、前記平行直線上の一部にも前記第２相に接触しない平行直線がある場合は、前記接触しない平行直線間の間隔は、青色光の発光ピーク波長未満であることが好ましい。 When a plurality of parallel straight lines are drawn in a direction parallel to the light emission direction on the surface of the green phosphor when cut in an arbitrary cross section parallel to the light emission direction, When two phases are in contact, or there is a parallel line that does not contact the second phase in part of the parallel line, the interval between the non-contact parallel lines is less than the emission peak wavelength of blue light. It is preferable that

本発明によれば、ＬｕＡＧ：Ｃｅを素材とした緑色蛍光体として発光強度や寿命等の特性を向上させることができる緑色蛍光体が提供される。 ADVANTAGE OF THE INVENTION According to this invention, the green fluorescent substance which can improve characteristics, such as emitted light intensity and a lifetime, as a green fluorescent substance which used LuAG: Ce as a raw material is provided.

本発明の実施形態に係る緑色蛍光体の外観の一例を示す概念斜視図である。It is a conceptual perspective view which shows an example of the external appearance of the green fluorescent substance which concerns on embodiment of this invention. 図１に示す緑色蛍光体をＡ−Ａ線で切ったときの断面ＳＥＭ写真である。It is a cross-sectional SEM photograph when the green fluorescent substance shown in FIG. 1 is cut by the AA line. 緑色蛍光体１におけるより好ましい形態を説明するための図２に示す断面ＳＥＭ写真を用いた説明図である。It is explanatory drawing using the cross-sectional SEM photograph shown in FIG. 2 for demonstrating the more preferable form in the green fluorescent substance 1. FIG. 本試験における緑色蛍光体の光特性の測定方法を説明する概略図である。It is the schematic explaining the measuring method of the optical characteristic of the green fluorescent substance in this test.

以下、本発明に係る緑色蛍光体を、実施の形態及び実施例を用いて詳細に説明する。
図１は、本発明の実施形態に係る緑色蛍光体の外観の一例を示す概念斜視図であり、図２は、図１に示す緑色蛍光体をＡ−Ａ線で切ったときの断面ＳＥＭ写真である。 Hereinafter, the green phosphor according to the present invention will be described in detail using embodiments and examples.
FIG. 1 is a conceptual perspective view showing an example of the appearance of a green phosphor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional SEM photograph of the green phosphor shown in FIG. 1 taken along line AA. It is.

本発明に係る緑色蛍光体１は、図１、２に示すように、例えば板状体で構成され、Ａｌ_２Ｏ_３からなる第１相３と、Ｃｅを含有するＬｕＡＧ（ルテチウム・アルミニウム・ガーネット：Ｌｕ_３Ａｌ_５Ｏ_１２）からなる第２相（蛍光体相）５とを有する無機材料で構成され、前記第２相５の含有量は、前記第１相３及び前記第２相５を含む相全体における体積比で２５ｖｏｌ％以上９５ｖｏｌ％以下であり、かつ、前記第２相５における前記ＬｕＡＧ中のＣｅの含有量は、Ｌｕに対する原子比（Ｃｅ／Ｌｕ）で０．００３以上０．０３以下であることを特徴とする。
また、本発明に係る緑色蛍光体１は、前記第２相５の含有量は、前記第１相３及び前記第２相５を含む相全体における体積比で８０ｖｏｌ％以上９５ｖｏｌ％以下であり、かつ、前記第２相５における前記ＬｕＡＧ中のＣｅの含有量は、Ｌｕに対する原子比（Ｃｅ／Ｌｕ）で０．００１以上０．０３以下であることを特徴とする。 Green phosphor 1 according to the present invention, as shown in FIGS. 1 and 2, for example, a plate-shaped body, a first phase 3 consisting of _Al 2 _{O 3,} LuAG containing Ce (lutetium aluminum garnet : Lu ₃ Al ₅ O ₁₂ ) composed of an inorganic material having a second phase (phosphor phase) 5, and the content of the second phase 5 includes the first phase 3 and the second phase 5. The volume ratio of the entire phase to be contained is 25 vol% or more and 95 vol% or less, and the Ce content in the LuAG in the second phase 5 is 0.003 or more and 0.003 or more in terms of the atomic ratio (Ce / Lu) to Lu. 03 or less.
Moreover, as for the green fluorescent substance 1 which concerns on this invention, content of the said 2nd phase 5 is 80 vol% or more and 95 vol% or less by the volume ratio in the whole phase containing the said 1st phase 3 and the said 2nd phase 5, In addition, the content of Ce in the LuAG in the second phase 5 is 0.001 or more and 0.03 or less in terms of atomic ratio (Ce / Lu) to Lu.

本発明に係る緑色蛍光体は、上述したような構成を備えているため、ＬｕＡＧ：Ｃｅを素材とした緑色蛍光体として発光強度や寿命等の特性を向上させることができる。 Since the green phosphor according to the present invention has the above-described configuration, characteristics such as emission intensity and lifetime can be improved as a green phosphor made of LuAG: Ce.

前記第２相５の含有量が体積比で２５ｖｏｌ％未満である場合には、第２相５の体積比が低いため励起光として用いる青色光（例えば、青色ＬＥＤ光）の一部が第２相５で波長変換されずにそのまま第１相３を透過してしまうため、色むらが発生し好ましくない。前記含有量が体積比で９５ｖｏｌ％を超える場合には、第２相５の体積比が大きく、光分散相となる第１相３の体積比が小さいため、緑色蛍光体１内における前記青色光の光分散が不十分となるため、緑色蛍光体１の面内で緑色光への波長変換量にばらつきが生じ、色むらが発生するため好ましくない。また、第１相３の体積比が極端に少なくなるため、熱伝導率が小さくなり、発光素子の放熱性が低下し、発光素子の寿命が低下するため好ましくない。 When the content of the second phase 5 is less than 25 vol% in volume ratio, a part of blue light (for example, blue LED light) used as excitation light is second because the volume ratio of the second phase 5 is low. Since the first phase 3 is transmitted as it is without being wavelength-converted in the phase 5, color unevenness occurs, which is not preferable. When the content exceeds 95 vol% in volume ratio, the volume ratio of the second phase 5 is large, and the volume ratio of the first phase 3 serving as the light dispersion phase is small. Since the dispersion of the light becomes insufficient, the amount of wavelength conversion to green light varies within the plane of the green phosphor 1, and color unevenness occurs, which is not preferable. Further, since the volume ratio of the first phase 3 is extremely reduced, the thermal conductivity is reduced, the heat dissipation of the light emitting element is lowered, and the life of the light emitting element is reduced, which is not preferable.

また、第２相５の含有量が体積比で２５ｖｏｌ％以上９５ｖｏｌ％以下である場合において、前記第２相５におけるＬｕＡＧ中のＣｅの含有量がＬｕに対する原子比（Ｃｅ／Ｌｕ）で０．００３未満である場合には、第２相５内のＣｅの含有量が少ないため、Ｃｅによる波長変換量が少なくなり、青色光の一部が第２相５で波長変換されずにそのまま第１相３を透過してしまうため、色むらが発生し好ましくない。前記原子比（Ｃｅ／Ｌｕ）が０．０３０を超える場合には、Ｃｅの含有量が高くなるためＬｕＡＧに固溶できないＣｅが偏析する場合があり、発光強度が低下するため好ましくない。 In addition, when the content of the second phase 5 is 25 vol% or more and 95 vol% or less by volume, the Ce content in LuAG in the second phase 5 is 0.00 by the atomic ratio (Ce / Lu) to Lu. If it is less than 003, the Ce content in the second phase 5 is small, so that the amount of wavelength conversion by Ce is reduced, and part of the blue light is not wavelength-converted in the second phase 5 and remains as it is in the first phase. Since phase 3 is transmitted, color unevenness occurs, which is not preferable. When the atomic ratio (Ce / Lu) exceeds 0.030, the Ce content is high, and Ce that cannot be dissolved in LuAG may be segregated, which is not preferable because the emission intensity decreases.

なお、前記第２相５の含有量が体積比で８０ｖｏｌ％以上９５ｖｏｌ％以下である場合は、前記第２相５におけるＬｕＡＧ中のＣｅの含有量が原子比（Ｃｅ／Ｌｕ）で０．００１以上であっても、本発明と同様な効果を得ることができる。
これは、第２相５内のＣｅの含有量は少ないものの、第２相５の体積比が大きいため、青色光のＣｅによる波長変換を十分に行うことができ、かつ、第２相５内でＣｅによって乱反射されるため、上述したような原子比（Ｃｅ／Ｌｕ）が０．００３未満である場合に発生する色むらは抑制されるものと考えられる。
なお、原子比（Ｃｅ／Ｌｕ）が０．００１未満である場合には、第２相５の体積比が大きくても、第２相５内のＣｅの含有量が極端に少なくなるため、Ｃｅによる波長変換量が極端に少なくなり、色むらが発生するため好ましくない。 When the content of the second phase 5 is 80 vol% or more and 95 vol% or less by volume, the content of Ce in LuAG in the second phase 5 is 0.001 in terms of atomic ratio (Ce / Lu). Even if it is above, the effect similar to this invention can be acquired.
This is because although the Ce content in the second phase 5 is small, the volume ratio of the second phase 5 is large, so that wavelength conversion by Ce of blue light can be sufficiently performed, and the second phase 5 Therefore, it is considered that color unevenness generated when the atomic ratio (Ce / Lu) as described above is less than 0.003 is suppressed.
When the atomic ratio (Ce / Lu) is less than 0.001, the Ce content in the second phase 5 is extremely reduced even if the volume ratio of the second phase 5 is large. This is not preferable because the amount of wavelength conversion due to is extremely reduced and color unevenness occurs.

図３は、上述した緑色蛍光体１におけるより好ましい形態を説明するための図２に示す断面ＳＥＭ写真を用いた説明図である。
上述した緑色蛍光体１は、緑色蛍光体１の光出射方向αに平行する任意の断面（例えば、図１に示すようなＡ−Ａ’線）で切ったときの表面（例えば、図２に示すような断面ＳＥＭ写真）において、前記光出射方向と平行する方向に任意の複数の平行直線（例えば、図３中、α１〜α１６）を引いた時に、すべての平行直線上に前記第２相５が接触していること（例えば、図３参照）が好ましく、前記平行直線上の一部にも前記第２相５に接触しない平行直線がある場合は、当該接触しない平行直線間の間隔は、青色光の発光ピーク波長（４５０〜４８０ｎｍ）未満であることが好ましい。
このような構成を備えることで、青色光そのものが緑色蛍光体１を通過するおそれがないため、緑色光を発生させる際の色むらの発生を確実に抑制することができるため好ましい。 FIG. 3 is an explanatory diagram using the cross-sectional SEM photograph shown in FIG. 2 for explaining a more preferable form of the green phosphor 1 described above.
The green phosphor 1 described above has a surface (for example, shown in FIG. 2) cut along an arbitrary cross section (for example, the AA ′ line as shown in FIG. 1) parallel to the light emission direction α of the green phosphor 1. In the cross-sectional SEM photograph as shown, when a plurality of arbitrary parallel straight lines (for example, α1 to α16 in FIG. 3) are drawn in a direction parallel to the light emitting direction, the second phase is placed on all the parallel straight lines. 5 are preferably in contact with each other (see, for example, FIG. 3), and when there is a parallel straight line that does not contact the second phase 5 in a part of the parallel straight line, the interval between the parallel lines not in contact is The emission wavelength of blue light is preferably less than 450 to 480 nm.
By providing such a configuration, it is preferable that the blue light itself does not pass through the green phosphor 1, and thus it is possible to reliably suppress the occurrence of color unevenness when green light is generated.

尚、上述した含有量については、緑色蛍光体１内における不可避的な不純物成分の混入を排除するものではないが、Ｆｅ、Ｃｒなどの金属不純物の総量は１００ｐｐｍ以下とすることが好ましい。
これによって、発光強度の低下や色むらの発生をより抑制することができ、また、発光ピーク波長の制御がより容易となるため好ましい。 In addition, about the content mentioned above, although the inevitable mixing of the impurity component in the green fluorescent substance 1 is not excluded, it is preferable that the total amount of metal impurities, such as Fe and Cr, shall be 100 ppm or less.
As a result, the decrease in emission intensity and the occurrence of color unevenness can be further suppressed, and the emission peak wavelength can be more easily controlled, which is preferable.

以下、本発明を実施例に基づいてさらに具体的に説明するが、本発明は、下記実施例により限定解釈されるものではない。 EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limitedly interpreted by the following Example.

（試験１）
平均粒径１．１μｍ、純度９９．９％の酸化セリウム粉末、平均粒径１．２μｍ、純度９９．９％の酸化ルテチウム粉末、平均粒径０．３μｍ、純度９９．９％の酸化アルミニウム粉末、エタノール、アクリル系バインダーを添加し酸化アルミニウムボールを用いたボールミルによって２０時間の混合を行って、得られたスラリからスプレードライヤを用いて造粒粉を作製した。この際、酸化セリウム粉末、酸化ルテチウム粉末及び酸化アルミニウム粉末の量を調整して、緑色蛍光体の相全体中のＬｕＡＧ：Ｃｅ含有量の異なる造粒粉を複数作製した。 (Test 1)
Cerium oxide powder having an average particle size of 1.1 μm and a purity of 99.9%, lutetium oxide powder having an average particle size of 1.2 μm and a purity of 99.9%, aluminum oxide powder having an average particle size of 0.3 μm and a purity of 99.9% Then, ethanol and an acrylic binder were added, and the mixture was mixed for 20 hours by a ball mill using aluminum oxide balls, and granulated powder was prepared from the resulting slurry using a spray dryer. At this time, by adjusting the amounts of the cerium oxide powder, the lutetium oxide powder, and the aluminum oxide powder, a plurality of granulated powders having different LuAG: Ce contents in the whole phase of the green phosphor were produced.

次に、作製した造粒粉を１０ＭＰａで一軸金型成形、１００ＭＰａで冷間静水圧成形(ＣＩＰ)を行って成形体とした。得られた成形体を、大気中６００℃で脱脂後、真空雰囲気下１７００℃（ＬｕＡＧ：Ｃｅ/Ａｌ_２Ｏ_３）で焼結した。 Next, the produced granulated powder was subjected to uniaxial mold molding at 10 MPa and cold isostatic pressing (CIP) at 100 MPa to obtain a molded body. The obtained molded body was degreased at 600 ° C. in the air and then sintered at 1700 ° C. (LuAG: Ce / Al ₂ O ₃ ) in a vacuum atmosphere.

得られた焼結体に対して、アルキメデス法により嵩密度（ＪＩＳＣ２１４１）を測定後、その一部を粉砕し、乾式自動密度計（島津製作所製アキュピック１３３０）にて、真密度を測定した。また、一部を洗浄後、Ｌｕ、Ａｌ、Ｃｅ濃度をＩＣＰ発光分光分析法にて測定した。また、一部を粉末Ｘ線回析により、結晶相を調査した。焼結体の密度、Ｌｕ濃度、Ａｌ濃度およびＣｅ濃度、結晶相の測定結果をもとに、相全体中のＡｌ_２Ｏ_３の含有量（第１相３の含有量）及びＬｕＡＧ：Ｃｅの含有量（第２相５の含有量）をそれぞれ体積比で計算し、また、第２相５におけるＣｅ／Ｌｕ原子比を計算した。このときＬｕＡＧ：Ｃｅ、Ａｌ_２Ｏ_３の密度は、それぞれ６．６９ｇ／ｃｍ^３、３．９９ｇ／ｃｍ^３として計算に使用した。 After the bulk density (JIS C 2141) was measured by the Archimedes method for the obtained sintered body, a part thereof was pulverized, and the true density was measured with a dry automatic densimeter (Accupic 1330 manufactured by Shimadzu Corporation). . Further, after cleaning a part, the concentrations of Lu, Al, and Ce were measured by ICP emission spectroscopic analysis. Moreover, a crystal phase was investigated by partly by powder X-ray diffraction. Based on the measurement results of the density, Lu concentration, Al concentration and Ce concentration, and crystal phase of the sintered body, the content of Al ₂ O _{3 in} the entire phase (content of the first phase 3) and the LuAG: Ce The content (content of the second phase 5) was calculated by volume ratio, and the Ce / Lu atomic ratio in the second phase 5 was calculated. At this time LuAG: Ce, density of _Al 2 _{O 3} is respectively 6.69 g ^/ cm 3, was used to calculate as 3.99 g / cm ^3.

また、得られた焼結体の一部をφ１０×２ｍｍに加工後、レーザフラッシュ法により熱伝導率を測定した。
なお、熱伝導率は放熱効果の点から１０Ｗ／(ｍ・Ｋ）以上を目標とし、１５Ｗ／(ｍ・Ｋ）以上の場合を○（良）、１０Ｗ／(ｍ・Ｋ）以上１５Ｗ／(ｍ・Ｋ）未満の場合を△（可）、１０Ｗ／(ｍ・Ｋ）未満の場合を×（不可）として判別した。 Further, after processing a part of the obtained sintered body to φ10 × 2 mm, the thermal conductivity was measured by a laser flash method.
The thermal conductivity is set to 10 W / (m · K) or more from the viewpoint of the heat radiation effect, and when it is 15 W / (m · K) or more, ○ (good), 10 W / (m · K) to 15 W / ( The case of less than m · K) was judged as Δ (possible) and the case of less than 10 W / (m · K) as x (impossible).

図４は、本試験における緑色蛍光体の光特性の測定方法を説明する概略図である。
本試験における光特性は、得られた焼結体を□１ｍｍ×０．２ｍｍの試料２０に加工後、青色ＬＥＤ素子（発光領域：□１ｍｍ、発光波長：＠４６０ｎｍ）２２上にシリコーン樹脂で固定した。ＬＥＤ前方に検出器（オーシャンオプティクス社製ＵＳＢ４０００ファイバマルチチャンネル分光器）２４を設置し、発光スペクトルを測定した。得られたスペクトルから発光ピーク波長、発光強度を算出した。また、焼結体の前方および側方より色むらを観察し、色むらの○（良）、×（不可）を判別した。 FIG. 4 is a schematic diagram for explaining a method for measuring the optical characteristics of the green phosphor in this test.
The optical characteristics in this test were obtained by processing the obtained sintered body into a □ 1 mm × 0.2 mm sample 20 and then fixing it on a blue LED element (light emitting area: □ 1 mm, light emitting wavelength: @ 460 nm) 22 with a silicone resin. did. A detector (USB4000 fiber multichannel spectrometer manufactured by Ocean Optics) 24 was installed in front of the LED, and the emission spectrum was measured. The emission peak wavelength and emission intensity were calculated from the obtained spectrum. Further, color unevenness was observed from the front and side of the sintered body, and ○ (good) and x (impossible) of color unevenness were determined.

発光強度はＬｕＡＧ：Ｃｅ蛍光体（（Ｃｅ／Ｌｕ）＝０．０１）の測定結果を１００とし、１１０以上の場合を○（良）、１００以上１１０未満の場合を△（可）、１００未満の場合を×（不可）とした。 Luminescence intensity is measured with LuAG: Ce phosphor ((Ce / Lu) = 0.01) as 100, ○ (good) when 110 or more, △ (good) when 100 or less and less than 110, less than 100 In the case of x, it was set as x (impossible).

また、総合評価として、発光強度、色むら、熱伝導率の各項目について、○（良）が２個以上の場合は○（良）、×（不可）が１個でもある場合は×（不可）、その他を△（可）と判別した。
以上の試験１の結果をまとめて表１に示す。 In addition, as a comprehensive evaluation, for each item of light emission intensity, color unevenness, and thermal conductivity, ○ (good) when there are two or more ○ (good), × (impossible) when there is even one x (impossible) ), And others were determined to be △ (possible).
The results of Test 1 above are summarized in Table 1.

表１に示すように、緑色蛍光体の相全体におけるＬｕＡＧ：Ｃｅの含有量（第２相の含有量）が体積比で２５ｖｏｌ％以上９５ｖｏｌ％以下とすることで、緑色光の波長領域内で発光強度及び熱伝導率が向上し、かつ、色むらが発生しない緑色蛍光体が得られることが認められる。 As shown in Table 1, the content of LuAG: Ce (content of the second phase) in the entire phase of the green phosphor is set to 25 vol% or more and 95 vol% or less in the volume ratio of green light within the wavelength range of green light. It can be seen that a green phosphor with improved emission intensity and thermal conductivity and no color unevenness can be obtained.

（試験２）
試験１の結果に基づいて、次に、酸化セリウム粉末、酸化ルテチウム粉末及び酸化アルミニウム粉末の量を調整して、緑色蛍光体中のＬｕＡＧ：Ｃｅの含有量及びＣｅ／Ｌｕ原子比の異なる平均粒径５０μmの造粒粉を複数作製した。 (Test 2)
Based on the results of Test 1, next, the amounts of cerium oxide powder, lutetium oxide powder and aluminum oxide powder were adjusted to obtain different average grains having different LuAG: Ce content and Ce / Lu atomic ratio in the green phosphor. A plurality of granulated powders having a diameter of 50 μm were prepared.

次に、試験１と同様な条件で焼結後、得られた焼結体に対して、試験１と同様な方法で、相全体中のＡｌ_２Ｏ_３の含有量（第１相３の含有量）、ＬｕＡＧ：Ｃｅの含有量（第２相５の含有量）及び第２相５におけるＣｅ／Ｌｕ原子比に対する発光ピーク波長、発光強度、色むら、熱伝導率をそれぞれ評価し、判別した。
以上の試験２の結果をまとめて表２に示す。 Next, after sintering under the same conditions as in Test 1, the obtained sintered body was subjected to the same method as in Test 1 to contain the content of Al ₂ O _{3 in} the entire phase (inclusion of first phase 3 Amount), LuAG: Ce content (second phase 5 content) and emission peak wavelength, emission intensity, color unevenness, and thermal conductivity with respect to the Ce / Lu atomic ratio in the second phase 5 were evaluated and discriminated. .
The results of Test 2 above are summarized in Table 2.

表２に示すように、第２相５におけるＣｅ／Ｌｕ原子比が０．００３以上０．０３以下である場合に、緑色光の波長領域内で発光強度及び熱伝導率が向上し、かつ、色むらが発生しない緑色蛍光体が得られることが認められる。また、ＬｕＡＧ：Ｃｅの含有量（第２相の含有量）が体積比で８０ｖｏｌ％以上９５ｖｏｌ％以下である場合は、第２相５におけるＣｅ／Ｌｕ原子比が０．００１以上で、同様な効果が得られることが認められる。 As shown in Table 2, when the Ce / Lu atomic ratio in the second phase 5 is 0.003 or more and 0.03 or less, the emission intensity and thermal conductivity are improved in the wavelength region of green light, and It can be seen that a green phosphor with no color unevenness is obtained. Further, when the content of LuAG: Ce (content of the second phase) is 80 vol% or more and 95 vol% or less by volume ratio, the Ce / Lu atomic ratio in the second phase 5 is 0.001 or more, and the same It is recognized that an effect is obtained.

１緑色蛍光体
３第１相
５第２相 1 Green phosphor 3 First phase 5 Second phase

Claims

A green fluorescent sintered body composed of an inorganic material having a first phase made of Al ₂ O ₃ and a second phase made of LuAG containing Ce,
The content of the second phase is 25 vol% or more and 95 vol% or less in a volume ratio in the entire phase including the first and second phases, and the content of Ce in the LuAG is an atomic ratio with respect to Lu ( A green phosphor having a Ce / Lu) of 0.003 or more and 0.03 or less.

A green fluorescent sintered body composed of an inorganic material having a first phase made of Al ₂ O ₃ and a second phase made of LuAG containing Ce,
The content of the second phase is 80 vol% or more and 95 vol% or less by volume ratio in the whole phase including the first and second phases, and the content of Ce in the LuAG is an atomic ratio with respect to Lu ( A green phosphor having a Ce / Lu ratio of 0.001 or more and 0.03 or less.

3. The green phosphor according to claim 1, wherein the green phosphor has a plurality of arbitrary parallel straight lines in a direction parallel to the light emission direction on a surface of the green phosphor cut in an arbitrary cross section parallel to the light emission direction. When the second phase is in contact with all the parallel straight lines or a part of the parallel straight lines is not in contact with the second phase when A green phosphor characterized in that the distance between the straight lines is less than the emission peak wavelength of blue light.