JP4202657B2 - Piezoelectric ceramic composition and piezoelectric device - Google Patents
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【０００１】
【発明の属する技術分野】
この発明は音響素子、圧電アクチュエータ等の圧電デバイスの材料として好適な圧電磁器組成物とこの圧電磁器組成物を使用した圧電デバイスに関するものである。
【０００２】
【従来の技術】
音響素子、圧電アクチュエータ等の圧電デバイスの電気機械変換材料として圧電磁器組成物が使用されている。圧電デバイスに使用される圧電磁器組成物の特性としては高Ｋｒ、高ε、低ヤング率、高抗破壊強度、ある程度の電気抵抗、高キュリー温度等が必要になる。そして、このような特性を満足する圧電磁器組成物として種々のものが提案されている。
【０００３】
例えば、圧電磁器組成物の一つの組成系として、Ｐｂａ｛Ｚｒｂ・Ｔｉｃ・（Ｎｉ１／３Ｎｂ２／３）ｄ・（Ｚｎ１／３Ｎｂ２／３）ｅ｝Ｏ３で表わされるものが知られている。この種の組成系の圧電磁器組成物としては、例えば特公昭４８−８４３４号公報、特公昭６０−２２５１６号公報、特公昭６４−７０３２号公報等に記載されているものが提案されている。
【０００４】
特公昭４８−８４３４号公報に記載された圧電磁器組成物は、上記組成式において、ａが１．００、ｂが０．０１≦ｂ≦０．７、ｃが０．１≦c≦０．６、ｄが０．０１≦ｄ≦０．５５、ｅが０．０１≦ｅ≦０．７であり、Ｐｂの３〜１５原子％がＣａ，Ｓｒ，Ｂａの少なくとも１種によって置換されたものからなる。
【０００５】
また、特公昭６０−２２５１６号公報に記載された圧電磁器組成物は、上記組成式において、ａが１．００、ｂが０．０１≦ｂ≦０．７、ｃが０．１≦ｃ≦０．６、ｄが０．０１≦ｄ≦０．５５、ｅが０．０１≦ｅ≦０．７であり、Ｐｂの３〜１５原子％がＳｒによって置換され、０．２５〜１．５０重量％のＬｉ２ＣＯ３を更に含むものからなる。
【０００６】
特公昭６４−７０３２号公報に記載された圧電磁器組成物は、上記組成式において、ａが０．９６≦ａ≦０．９８５、ｂが０．０７５≦ｂ≦０．３７５、ｃが０．２０≦ｃ≦０．４０、ｄが０≦ｄ≦０．５０、ｅが０≦ｅ≦０．７０になっているものや、これのＰｂの５原子％までをＣａ，Ｓｒ，Ｂａの少なくとも１種によって置換されているものや、Ｌｉ２Ｏ等の金属酸化物を更に含んでいるもの等からなる。
【０００７】
圧電材料を用いた圧電素子は従来、単層構造であった。即ち、セラミックスを焼成したあとに、Ａｇ等の電極を焼きつけるなどして、デバイスを作成していた。従って、セラミックスの焼成温度はデバイスを作成する上では大きな障害はなかった。
【０００８】
近年、圧電デバイスの性能の向上、低電圧駆動化などから、積層構造化が進められてきた。これらの代表的なデバイスには、積層型圧電アクチュエータがある。積層型素子の場合、主に積層コンデンサーなどと同様、セラミックス材料をシート化し、そのグリーンシートに電極ペーストを印刷塗布後、熱圧着で数から数十層積層したものを焼成で焼き固めて作られる。即ち、セラミックス材料の焼成温度で使用できる電極材料が決まってくることになる。
【０００９】
上記のような圧電磁器組成物を用いて積層型圧電デバイスを製造する場合、内部電極の材料としてはPt、あるいはＡｇ−Ｐｄ合金が一般的に使用されている。
【００１０】
【発明が解決しようとする課題】
しかし、上記従来の圧電磁器組成物はいずれも焼結温度が１１３０〜１３００℃と高いので、同時焼成する内部電極の材料としてＰｔやＰｄ含有率の多いＡｇ−Ｐｄ合金を使用しなければならない。即ち、圧電デバイスがコスト高になるという問題があった。
【００１１】
また、上記従来の圧電磁器組成物はいずれも焼結温度が１１３０〜１３００℃と高いので、焼結のための熱エネルギーが大量に必要であり、熱エネルギーのためにコストがかかるのみならず、環境に与える負荷が大きいという問題があった。
【００１２】
また、上記従来の圧電磁器組成物はいずれも焼結温度が１１３０〜１３００℃と高いので、焼成の際のＰｂＯの蒸発量が多く、工場内における作業環境が悪化するおそれがあるという問題があった。
【００１３】
この発明は、９００℃以下の低い温度で焼結させることができ、しかもセラミック粒子の粒径が小さく、機械的強度の高い（抗折強度が９００ｋｇ／ｃｍ２以上）圧電磁器組成物を提供することを目的とする。
【００１４】
【課題を解決するための手段】
この発明は圧電磁器組成物とこの圧電磁器組成物を使用した圧電デバイスに関するものであり、該圧電磁器組成物は、式Ｐｂａ｛Ｚｒｂ・Ｔｉｃ・（Ｎｉ１／３Ｎｂ２／３）ｄ・（Ｚｎ１／３Ｎｂ２／３）ｅ｝Ｏ３で表わされるペロブスカイト組成物と該ペロブスカイト組成物中に含まれるＡｇ２Ｏとからなり、該式Ｐｂａ｛Ｚｒｂ・Ｔｉｃ・（Ｎｉ１／３Ｎｂ２／３）ｄ・（Ｚｎ１／３Ｎｂ２／３）ｅ｝Ｏ３中のａ，ｂ，ｃ，ｄ，ｅがｂ＋ｃ＋ｄ＋ｅ＝１としたときに１．０００≦ａ≦１．０２０、０．２６≦ｂ≦０．３、０．３４≦ｃ≦０．４０、０．１０≦ｄ≦０．３５、０．０７≦ｅ≦０．１４の範囲にあり、Ａｇ２Ｏが０．００５〜０．０３ｗｔ％の割合で含まれていることを特徴とするものである。
【００１５】
ここで、Ａｇ２Ｏをペロブスカイト組成物に対し０．００５〜０．０３ｗｔ％添加したのは、０．００５ｗｔ％以下のＡｇ２Ｏ添加では焼結体の粒径が大きくなり過ぎ、試料抗折力が小さくなってしまい、０．０３ｗｔ％以上のＡｇ２Ｏ添加では焼結体中に２次相が析出して圧電特性が低下してしまうが、０．００５〜０．０３ｗｔ％の範囲でＡｇ２Ｏを添加した場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られるからである。
【００１６】
また、ａを１．０００≦ａ≦１．０２０としたのは、ａ＜１．０００では優れた圧電特性は得られるものの、Ａｇを添加しても低温焼結が不可能であり、１１００℃程度の高い焼結温度を要し、１．０２０＜ａではＰｂ２次相が大量に析出して圧電特性が低下し、実用に耐えられなくなるが、１．０００≦ａ≦１．０２０の範囲の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られるからである。
【００１７】
また、bを０．２６≦ｂ≦０．３１としたのは、b＜０．２６では優れた圧電特性が得られず、また、本請求項のａ値範囲のうち高いａ値範囲のみでしか低温焼結が不可能となり、０．３１＜bでは結晶構造が変化し、優れた圧電特性が得られず、また、高いａ値範囲のみででしか低温焼結ができないが、０．２６≦ｂ≦０．３１の範囲の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られるからである。
【００１８】
また、cを０．３４≦ｃ≦０．４０としたのは、c＜０．３４では優れた圧電特性が得られず、また、本請求項のａ値範囲のうち高いａ値範囲のみでしか低温焼結ができず、０．４０＜cでは優れた圧電特性が得られず、また、高いａ値範囲のみでしか低温焼結ができないが、０．３４≦ｃ≦０．４０の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られるからである。
【００１９】
また、dを０．１０≦ｄ≦０．３５としたのは、d＜0.10ではキュリー温度が高く、優れた圧電特性が得られないし、本請求項のａ値範囲のうち高いａ値範囲のみでしか低温焼結ができず、０．３５＜dではキュリー温度が下がりすぎ、実用に耐えることができなくなり、また、本請求項のａ値範囲のうち高いａ値範囲のみでしか低温焼結が不可能となるが、０．１０≦ｄ≦０．３５の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られるからである。
【００２０】
また、ｅを０．０７≦ｅ≦０．１４としたのは、ｅ＜０．０７では優れた圧電特性は得られるが、本請求項のａ値範囲のうち高いａ値範囲のみでしか低温焼結ができなくなり、また、焼成による粒成長が抑えられなくなり、試料抗折力が小さくなってしまい、０．１４＜ｅでは優れた圧電特性は得られるが、本請求項のａ値範囲のうち高いａ値範囲のみでしか低温焼結ができなくなるが、０．０７≦ｅ≦０．１４の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られるからである。
【００２１】
【発明の実施の形態】
まず、ＰｂＯ，ＺｒＯ２，ＴｉＯ２，ＮｉＯ，ＺｎＯ，Ｎｂ２Ｏ５，Ａｇ２Ｏからなる原料粉末を各々準備し、これらを表１に示す割合で秤量し、ポットミル内にジルコニアビーズ、イオン交換水と共に入れ、１５時間湿式混合し、得られた懸濁液をバットに移し、乾燥器内に入れ、１５０℃で乾燥させた。
【００２２】
次に、この乾燥によって得られた混合物を、大気雰囲気下において電気炉を用いて８５０℃で２時間焼成した。混合物内の各金属酸化物はこの焼成によって相互に固相反応し、ペロブスカイト化合物が形成された。
【００２３】
次に、このペロブスカイト化合物をポットミル内にジルコニアビーズ、イオン交換水と共に入れ、１５時間湿式解砕し、得られた懸濁液をバットに移し、乾燥器内に入れ、１５０℃で乾燥させ、完成粉体を得た。
【００２４】
次に、この完成粉体に有機バインダーを少量混合し、加圧プレス機を用い、圧力１．５ＭＰａで圧縮成型し、直径８ｍｍ、厚さ０．５ｍｍの円板形の試料を得た。
【００２５】
次に、この試料を電気炉内に入れ、大気雰囲気下において９００℃〜１０５０℃で２時間焼成し、その後この試料を電気炉から取り出し、試料の両面にフリットレスＡｇペーストを印刷し、大気雰囲気下において７００℃で焼き付け、これを外部電極とした。
【００２６】
次に、この外部電極付きの試料に、１００℃の下で、１．５ｋＶ／ｍｍの電圧を３分間印加し、試料を分極させた。
【００２７】
次に、この分極させた試料の圧電特性Ｋｒを測定したところ、表１に示す通りであった。圧電特性Ｋｒ測定は、日本電子材料工業会標準規格（EMAS規格）にのっとり、インピーダンス測定を行い、算出した。
【００２８】
また、試料を形成しているセラミック粒子の粒径を測定したところ、表１に示す通りであった。粒径測定は、電子顕微鏡を用い、試料の表面を５０００倍に拡大した写真をもとに、写真の一定方向に各粒子の最長の長さを測定してその粒子の粒径とみなし、各試料につき２００粒を測定、その平均を試料粒径とした。
【００２９】
また、焼結体試料の抗折力は３点曲げ測定破壊荷重値から計算により求めた。３点曲げ測定法と破壊強度計算式はＪＩＳ規格Ｒ−１６０１にのっとり行った。３点曲げ測定用試料形状は上記Ｋｒ測定用形状とは異なる。圧力１．５ＭＰａで圧縮成型し、長さ３０ｍｍ、幅３．５ｍｍ、厚み２．７ｍｍの直方形とした。焼成後、ＪＩＳ規格Ｒ−１６０１に沿うよう研磨し試料サイズをあわせた。
【００３０】
【表１】
表１に示す結果から、試料Ｎｏ．１に示すようにＡｇ２Ｏの添加がない場合は焼結体の粒径が大きくなって抗折力が小さくなり、試料Ｎｏ．５に示すように０．０４ｗｔ％のＡｇ２Ｏ添加では焼結体中に二次相が析出して圧電特性が低下してしまうが、試料Ｎｏ．２〜４に示すように０．００５〜０．０３ｗｔ％の範囲でＡｇ２Ｏを添加した場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られることがわかる。
【００３２】
また、試料Ｎｏ．６に示すようにａが０．９９５では焼結温度が１０５０℃と高くなり、試料Ｎｏ．１０に示すようにａが１．０２５では圧電特性が５１％と悪くなるが、試料Ｎｏ．７〜９に示すように１．０００≦ａ≦１．０２０の範囲の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られることがわかる。
【００３３】
また、試料Ｎｏ．１１に示すようにbが０．２４では圧電特性が５２％と悪くなり、また、焼結温度が９５０℃と高くなり、試料Ｎｏ．１５に示すようにbが０．３３では圧電特性が５０％と悪くなり、また、焼結温度が９５０℃と高くなるが、試料Ｎｏ．１２〜１４に示すように０．２６≦ｂ≦０．３１の範囲の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られることがわかる。
【００３４】
また、試料Ｎｏ．１６に示すようにcが０．３２では圧電特性が５３％と悪くなり、焼結温度が９５０℃と高くなり、試料Ｎｏ．２０に示すようにcが０．４２では圧電特性が５２％と悪くなり、また、焼結温度が９５０℃と高くなるが、試料Ｎｏ．１７〜１９に示すように０．３４≦ｃ≦０．４０の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られることがわかる。
【００３５】
また、試料Ｎｏ．２１に示すようにdが０．０５では圧電特性が４９％と悪くなり、焼結温度が９５０℃と高くなり、試料Ｎｏ．２５に示すようにdが０．４０では焼結温度が９５０℃と高くなるが、試料Ｎｏ．２２〜２４に示すように０．１０≦ｄ≦０．３５の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られることがわかる。
【００３６】
また、試料Ｎｏ．２６に示すようにeが０．０２では焼結温度が９５０℃と高くなり、焼成による粒成長が抑えられなくなり、粒径が大きくなって抗折力が小さくなり、試料Ｎｏ．３０に示すようにeが０．２０では焼結温度が１０００℃と高くなるが、試料Ｎｏ．２７〜２９に示すように０．０７≦ｅ≦０．１４の場合は９００℃の焼成で圧電特性の良い、セラミック粒子の粒径の小さな圧電磁器組成物が得られることがわかる。
【００３７】
なお、本実施例では出発原料をＰｂＯ、ＺｒＯ2、ＴｉＯ2、ＮｉＯ、ＺｎＯ、Ｎｂ2Ｏ5及びＡｇ2Ｏとし、これらを全て一緒に混合、仮焼して圧電材料粉を作成したが、ＰｂＺｒＯ3、ＰｂＴｉＯ3、Ｐｂ（Ｎｉ１／３Ｎｂ２／３)Ｏ３、Ｐｂ（Ｚｎ１／３Ｎｂ２／３）Ｏ3などを一部又は全部に用いても、最終組成比率が同じものになるように調整されていればよい。又、Ａｇ2Ｏは酢酸Ａｇ、炭酸Ａｇあるいは金属Ａｇパウダーを使用することもできる。
【００３８】
【発明の効果】
この発明によれば、焼結温度を９００℃以下にすることができるので、内部電極の貴金属比率を減らして製品のコストダウンを図ることができるという効果がある。
【００３９】
また、この発明によれば、焼結温度を９００℃以下にすることができるので、焼成時の熱量低減により熱エネルギーコストを減らすとともに、環境負荷を減らすことができるという効果がある。
【００４０】
また、この発明によれば、焼結温度を９００℃以下にすることができるので、焼成の際のＰｂＯの蒸発を少なくすることができ、工場内における作業環境を良好ならしめることができるという効果がある。
【００４１】
また、この発明によれば、圧電特性ｋｒを５５％以上と実用可能なエネルギー変換効率を有する圧電磁器組成物を得ることができるという効果がある。
【００４２】
また、この発明によれば、焼成による粒成長を抑え、粒径が１．６μｍ以下と小さくて緻密な、強度の高い、薄層の積層素子の材料として好適な圧電磁器組成物を得ることができるという効果がある。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric ceramic composition suitable as a material for piezoelectric devices such as acoustic elements and piezoelectric actuators, and a piezoelectric device using the piezoelectric ceramic composition.
[0002]
[Prior art]
Piezoelectric ceramic compositions are used as electromechanical conversion materials for piezoelectric devices such as acoustic elements and piezoelectric actuators. As characteristics of the piezoelectric ceramic composition used for the piezoelectric device, high Kr, high ε, low Young's modulus, high anti-destructive strength, some electric resistance, high Curie temperature, and the like are required. Various piezoelectric ceramic compositions that satisfy such characteristics have been proposed.
[0003]
For example, one composition system of a piezoelectric ceramic composition is represented by Pb a {Zr b · Ti c · (Ni 1/3 Nb 2/3 ) d · (Zn 1/3 Nb 2/3 ) e } O 3 . Is known. As this type of piezoelectric ceramic composition, those described in, for example, Japanese Patent Publication No. 48-8434, Japanese Patent Publication No. 60-22516, Japanese Patent Publication No. 64-7032, and the like have been proposed.
[0004]
In the piezoelectric ceramic composition described in Japanese Patent Publication No. 48-8434, in the above composition formula, a is 1.00, b is 0.01 ≦ b ≦ 0.7, and c is 0.1 ≦ c ≦ 0. 6, d is 0.01 ≦ d ≦ 0.55, e is 0.01 ≦ e ≦ 0.7, and 3 to 15 atomic% of Pb is substituted by at least one of Ca, Sr, and Ba Consists of.
[0005]
In addition, the piezoelectric ceramic composition described in Japanese Patent Publication No. 60-22516 has the above composition formula in which a is 1.00, b is 0.01 ≦ b ≦ 0.7, and c is 0.1 ≦ c ≦. 0.6, d is 0.01 ≦ d ≦ 0.55, e is 0.01 ≦ e ≦ 0.7, 3 to 15 atomic% of Pb is substituted by Sr, and 0.25 to 1.50. It further comprises wt% Li 2 CO 3 .
[0006]
The piezoelectric ceramic composition described in Japanese Examined Patent Publication No. 64-7032 has the above composition formula, in which a is 0.96 ≦ a ≦ 0.985, b is 0.075 ≦ b ≦ 0.375, and c is 0.00. 20 ≦ c ≦ 0.40, d is 0 ≦ d ≦ 0.50, e is 0 ≦ e ≦ 0.70, or up to 5 atomic% of Pb, at least of Ca, Sr, Ba It is composed of one that is substituted by one type or one that further contains a metal oxide such as Li 2 O.
[0007]
Conventionally, a piezoelectric element using a piezoelectric material has a single layer structure. That is, after firing ceramics, an electrode such as Ag is baked to produce a device. Therefore, the firing temperature of the ceramics was not a major obstacle to making a device.
[0008]
In recent years, a laminated structure has been promoted from the viewpoint of improving the performance of a piezoelectric device and lowering the voltage. A typical example of these devices is a laminated piezoelectric actuator. In the case of multi-layered elements, it is mainly made like a multi-layer capacitor by making a ceramic material into a sheet, printing and applying electrode paste on the green sheet, and then laminating several to several tens of layers by thermocompression bonding. . That is, the electrode material that can be used at the firing temperature of the ceramic material is determined.
[0009]
When a laminated piezoelectric device is manufactured using the piezoelectric ceramic composition as described above, Pt or an Ag—Pd alloy is generally used as a material for the internal electrode.
[0010]
[Problems to be solved by the invention]
However, since all of the above conventional piezoelectric ceramic compositions have a sintering temperature as high as 1130 to 1300 ° C., an Ag—Pd alloy having a high Pt or Pd content must be used as a material for the internal electrodes to be simultaneously fired. That is, there is a problem that the cost of the piezoelectric device is increased.
[0011]
In addition, since the conventional piezoelectric ceramic composition has a sintering temperature as high as 1130 to 1300 ° C., a large amount of thermal energy is required for sintering, and not only costs for thermal energy are required, There was a problem that the load on the environment was large.
[0012]
In addition, since all of the above conventional piezoelectric ceramic compositions have a sintering temperature as high as 1130 to 1300 ° C., there is a problem that the amount of PbO evaporation during firing is large and the working environment in the factory may be deteriorated. It was.
[0013]
The present invention provides a piezoelectric ceramic composition that can be sintered at a low temperature of 900 ° C. or less, has a small ceramic particle size, and has a high mechanical strength (a bending strength of 900 kg / cm 2 or more). For the purpose.
[0014]
[Means for Solving the Problems]
The present invention relates to a piezoelectric ceramic composition and a piezoelectric device using the piezoelectric ceramic composition, and the piezoelectric ceramic composition has the formula Pb a {Zr b · Ti c · (Ni 1/3 Nb 2/3 ) d · (Zn 1/3 Nb 2/3 ) e } O 3 and a perovskite composition and Ag 2 O contained in the perovskite composition, and the formula Pb a {Zr b · Ti c · ( Ni 1/3 Nb 2/3 ) d · (Zn 1/3 Nb 2/3 ) e } When a, b, c, d, e in O 3 are b + c + d + e = 1, 1.000 ≦ a ≦ 1.020, 0.26 ≦ b ≦ 0.3, 0.34 ≦ c ≦ 0.40, 0.10 ≦ d ≦ 0.35, 0.07 ≦ e ≦ 0.14, and Ag 2 O is contained at a ratio of 0.005 to 0.03 wt%.
[0015]
Here, the added 0.005～0.03Wt% relative perovskite composition Ag 2 O is too large particle size of the sintered body is 0.005 wt% or less of Ag 2 O is added, the sample bending The force becomes small, and addition of 0.03 wt% or more of Ag 2 O causes a secondary phase to precipitate in the sintered body and lowers the piezoelectric characteristics, but in the range of 0.005 to 0.03 wt%. This is because when Ag 2 O is added, a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle size can be obtained by firing at 900 ° C.
[0016]
Further, a is set to 1.000 ≦ a ≦ 1.020. Although excellent piezoelectric characteristics can be obtained when a <1.000, low temperature sintering is impossible even when Ag is added. A high sintering temperature is required, and when 1.020 <a, a large amount of Pb secondary phase is precipitated and the piezoelectric properties are deteriorated, so that it cannot be put into practical use. However, the range is 1.000 ≦ a ≦ 1.020. This is because a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle diameter can be obtained by firing at 900 ° C.
[0017]
Further, b is set to 0.26 ≦ b ≦ 0.31 because excellent piezoelectric characteristics cannot be obtained when b <0.26, and only in the high a value range in the a value range of the present claims. However, low-temperature sintering becomes impossible, and when 0.31 <b, the crystal structure changes, and excellent piezoelectric characteristics cannot be obtained. Further, low-temperature sintering can be performed only in a high a value range. This is because, in the range of ≦ b ≦ 0.31, a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle size can be obtained by firing at 900 ° C.
[0018]
Also, the reason why c is set to 0.34 ≦ c ≦ 0.40 is that excellent piezoelectric characteristics cannot be obtained when c <0.34, and only in the high a value range in the a value range of the present claims. However, low-temperature sintering is not possible, and excellent piezoelectric properties cannot be obtained when 0.40 <c, and low-temperature sintering is possible only in a high a value range, but 0.34 ≦ c ≦ 0.40 This is because a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle diameter can be obtained by firing at 900 ° C.
[0019]
The reason why d is set to 0.10 ≦ d ≦ 0.35 is that when d <0.10, the Curie temperature is high, and excellent piezoelectric characteristics cannot be obtained. Low temperature sintering is possible only at 0.35 <d, and the Curie temperature is too low to withstand practical use, and low temperature sintering is possible only in the high a value range of the a value range of the claims. However, in the case of 0.10 ≦ d ≦ 0.35, a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle size can be obtained by firing at 900 ° C.
[0020]
In addition, e is set to 0.07 ≦ e ≦ 0.14. Although excellent piezoelectric characteristics can be obtained when e <0.07, the temperature is low only in a high a value range in the a value range of the present claims. Sintering becomes impossible, grain growth due to firing cannot be suppressed, and the sample bending strength becomes small, and excellent piezoelectric characteristics can be obtained when 0.14 <e. Of these, low-temperature sintering can be performed only in a high a value range, but in the case of 0.07 ≦ e ≦ 0.14, a piezoelectric ceramic composition having good piezoelectric properties and small ceramic particle size by firing at 900 ° C. It is because it is obtained.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
First, raw material powders made of PbO, ZrO 2 , TiO 2 , NiO, ZnO, Nb 2 O 5 , Ag 2 O were prepared and weighed at the ratios shown in Table 1, and zirconia beads and ion exchange were placed in a pot mill. It was put together with water and wet mixed for 15 hours, and the resulting suspension was transferred to a vat, placed in a drier and dried at 150 ° C.
[0022]
Next, the mixture obtained by this drying was fired at 850 ° C. for 2 hours in an air atmosphere using an electric furnace. Each metal oxide in the mixture reacted with each other by solid phase reaction to form a perovskite compound.
[0023]
Next, this perovskite compound is put in a pot mill together with zirconia beads and ion-exchanged water, wet disintegrated for 15 hours, and the resulting suspension is transferred to a vat and dried in a dryer at 150 ° C. to complete. A powder was obtained.
[0024]
Next, a small amount of an organic binder was mixed with the finished powder, and compression molding was performed at a pressure of 1.5 MPa using a pressure press machine to obtain a disk-shaped sample having a diameter of 8 mm and a thickness of 0.5 mm.
[0025]
Next, this sample is put in an electric furnace and baked at 900 ° C. to 1050 ° C. for 2 hours in an air atmosphere. Thereafter, the sample is taken out from the electric furnace, and a fritless Ag paste is printed on both surfaces of the sample. Under baking was performed at 700 ° C., and this was used as an external electrode.
[0026]
Next, a voltage of 1.5 kV / mm was applied to the sample with external electrodes at 100 ° C. for 3 minutes to polarize the sample.
[0027]
Next, when the piezoelectric characteristics Kr of the polarized sample were measured, they were as shown in Table 1. The piezoelectric property Kr measurement was calculated by measuring impedance according to the Japan Electronic Materials Industry Standard (EMAS standard).
[0028]
Further, when the particle diameter of the ceramic particles forming the sample was measured, it was as shown in Table 1. For the particle size measurement, an electron microscope was used to measure the longest length of each particle in a certain direction of the photo based on a photograph in which the surface of the sample was magnified 5000 times. 200 particles were measured for each sample, and the average was taken as the sample particle size.
[0029]
Moreover, the bending strength of the sintered compact sample was calculated | required by calculation from the three-point bending measurement fracture load value. The three-point bending measurement method and the fracture strength calculation formula were performed according to JIS standard R-1601. The three-point bending measurement sample shape is different from the Kr measurement shape. Compression molding was performed at a pressure of 1.5 MPa to form a rectangular shape having a length of 30 mm, a width of 3.5 mm, and a thickness of 2.7 mm. After firing, the sample size was adjusted by polishing in accordance with JIS standard R-1601.
[0030]
[Table 1]
From the results shown in Table 1, Sample No. As shown in FIG. 1, when Ag 2 O is not added, the particle size of the sintered body is increased and the bending strength is decreased. As shown in FIG. 5, when 0.04 wt% of Ag 2 O is added, a secondary phase is precipitated in the sintered body and the piezoelectric characteristics are deteriorated. When Ag 2 O is added in the range of 0.005 to 0.03 wt% as shown in 2 to 4, a piezoelectric ceramic composition with good piezoelectric characteristics and small ceramic particle size can be obtained by firing at 900 ° C. I understand that.
[0032]
Sample No. As shown in FIG. 6, when a is 0.995, the sintering temperature is as high as 1050 ° C. As shown in FIG. 10, when a is 1.025, the piezoelectric characteristics are as bad as 51%. 7 to 9, it can be seen that a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle diameter can be obtained by firing at 900 ° C. in the range of 1.000 ≦ a ≦ 1.020.
[0033]
Sample No. As shown in FIG. 11, when b is 0.24, the piezoelectric characteristics are deteriorated to 52%, and the sintering temperature is increased to 950 ° C. As shown in FIG. 15, when b is 0.33, the piezoelectric characteristics are degraded to 50% and the sintering temperature is increased to 950 ° C. As shown in 12-14, in the range of 0.26 ≦ b ≦ 0.31, it can be seen that a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle diameter can be obtained by firing at 900 ° C.
[0034]
Sample No. As shown in FIG. 16, when c is 0.32, the piezoelectric characteristics are degraded to 53%, the sintering temperature is increased to 950 ° C. As shown in FIG. 20, when c is 0.42, the piezoelectric characteristics are deteriorated to 52% and the sintering temperature is increased to 950 ° C. 17 to 19, it can be seen that a piezoelectric ceramic composition with good piezoelectric characteristics and small ceramic particle diameter can be obtained by firing at 900 ° C. when 0.34 ≦ c ≦ 0.40.
[0035]
Sample No. As shown in FIG. 21, when d is 0.05, the piezoelectric characteristics are deteriorated to 49%, the sintering temperature is increased to 950 ° C. 25, when d is 0.40, the sintering temperature is as high as 950 ° C. 22 to 24, when 0.10 ≦ d ≦ 0.35, it can be seen that a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle diameter can be obtained by firing at 900 ° C.
[0036]
Sample No. 26, when e is 0.02, the sintering temperature is as high as 950 ° C., grain growth due to firing cannot be suppressed, the grain size is increased and the bending strength is decreased. As shown in FIG. 30, when e is 0.20, the sintering temperature is as high as 1000 ° C. As shown in 27-29, it can be seen that in the case of 0.07 ≦ e ≦ 0.14, a piezoelectric ceramic composition having good piezoelectric characteristics and small ceramic particle size can be obtained by firing at 900 ° C.
[0037]
In this example, the starting materials were PbO, ZrO 2 , TiO 2 , NiO, ZnO, Nb 2 O 5 and Ag 2 O, all of which were mixed together and calcined to create a piezoelectric material powder. Even if some or all of PbZrO 3 , PbTiO 3 , Pb (Ni 1/3 Nb 2/3 ) O 3 , Pb (Zn 1/3 Nb 2/3 ) O 3 are used, the final composition ratio is the same. It may be adjusted so as to become. As Ag 2 O, acetic acid Ag, carbonic acid Ag, or metal Ag powder can be used.
[0038]
【The invention's effect】
According to this invention, since the sintering temperature can be made 900 ° C. or less, there is an effect that the cost of the product can be reduced by reducing the precious metal ratio of the internal electrodes.
[0039]
Moreover, according to this invention, since sintering temperature can be made 900 degrees C or less, it is effective in reducing an environmental burden while reducing a thermal energy cost by heat amount reduction at the time of baking.
[0040]
Moreover, according to this invention, since sintering temperature can be made 900 degrees C or less, the evaporation of PbO at the time of baking can be decreased, and the effect that the working environment in a factory can be made favorable. There is.
[0041]
Further, according to the present invention, there is an effect that a piezoelectric ceramic composition having a piezoelectric characteristic kr of 55% or more and a practical energy conversion efficiency can be obtained.
[0042]
In addition, according to the present invention, it is possible to obtain a piezoelectric ceramic composition suitable as a material for a thin layered element having a small particle size of 1.6 μm or less, a dense and high strength, and suppressing grain growth due to firing. There is an effect that can be done.
Claims (2)
１．０００≦ａ≦１．０２０
０．２６≦ｂ≦０．３１
０．３４≦ｃ≦０．４０
０．１０≦ｄ≦０．３５
０．０７≦ｅ≦０．１４Perovskite composition represented by the formula Pb a {Zr b · Ti c · (Ni 1/3 Nb 2/3 ) d · (Zn 1/3 Nb 2/3 ) e } O 3 and contained in the perovskite composition It consists of a Ag 2 O being, formula Pb a {Zr b · Ti c · (Ni 1/3 Nb 2/3) d · (Zn 1/3 Nb 2/3) e} O 3 in a, b , C, d, e are in the following range when b + c + d + e = 1, and Ag 2 O is contained in a proportion of 0.005 to 0.03 wt%.
1.000 ≦ a ≦ 1.020
0.26 ≦ b ≦ 0.31
0.34 ≦ c ≦ 0.40
0.10 ≦ d ≦ 0.35
0.07 ≦ e ≦ 0.14
１．０００≦ａ≦１．０２０
０．２６≦ｂ≦０．３１
０．３４≦ｃ≦０．４０
０．１０≦ｄ≦０．３５
０．０７≦ｅ≦０．１４One or more piezoelectric ceramics made of a piezoelectric ceramic composition and two or more electrodes sandwiching the piezoelectric ceramic, the piezoelectric ceramic composition having the formula Pb a {Zr b · Ti c · (Ni 1 / 3 Nb 2/3 ) d · (Zn 1/3 Nb 2/3 ) e } O 3 and a perovskite composition, and Ag 2 O contained in the perovskite composition, the formula Pb a {Zr b · Ti c · (Ni 1/3 Nb 2/3 ) d · (Zn 1/3 Nb 2/3 ) e } When a, b, c, d, e in O 3 are b + c + d + e = 1 in the range below, the piezoelectric device Ag 2 O is characterized in that it contains a proportion of 0.005~0.03wt%.
1.000 ≦ a ≦ 1.020
0.26 ≦ b ≦ 0.31
0.34 ≦ c ≦ 0.40
0.10 ≦ d ≦ 0.35
0.07 ≦ e ≦ 0.14
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| US9406866B2 (en) | 2011-12-20 | 2016-08-02 | Taiyo Yuden Co., Ltd. | Piezoelectric device with piezoelectric ceramic layer having AG segregated in voids in sintered body of perovskite composition |
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| JP2007230839A (en) * | 2006-03-02 | 2007-09-13 | Tdk Corp | Piezoelectric ceramic composition, multilayer piezoelectric element and method of manufacturing the same |
| JP4755919B2 (en) * | 2006-02-23 | 2011-08-24 | 富士フイルム株式会社 | Lead zirconate titanate composition, method for producing the same, piezoelectric body, and piezoelectric element |
| JP2007258301A (en) | 2006-03-22 | 2007-10-04 | Tdk Corp | Laminated piezoelectric element, and its manufacturing method |
| JP4238271B2 (en) | 2006-03-22 | 2009-03-18 | Ｔｄｋ株式会社 | Piezoelectric ceramic composition and multilayer piezoelectric element |
| JP4711083B2 (en) * | 2006-12-27 | 2011-06-29 | Ｔｄｋ株式会社 | Multilayer piezoelectric element |
| JP5931127B2 (en) | 2013-11-08 | 2016-06-08 | 太陽誘電株式会社 | Piezoelectric ceramics, method for manufacturing the same, and piezoelectric ceramic speaker having the same |
| JP6445372B2 (en) | 2015-03-31 | 2018-12-26 | 日本碍子株式会社 | Piezoelectric / electrostrictive material, piezoelectric / electrostrictive body, and resonance driving device |
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| US9406866B2 (en) | 2011-12-20 | 2016-08-02 | Taiyo Yuden Co., Ltd. | Piezoelectric device with piezoelectric ceramic layer having AG segregated in voids in sintered body of perovskite composition |
| US9614142B2 (en) | 2011-12-20 | 2017-04-04 | Taiyo Yuden Co., Ltd. | Piezoelectric ceramic composition constituted by Ag-segregated sintered body of zirconate-titanate type perovskite composition |
| US9755137B2 (en) | 2011-12-20 | 2017-09-05 | Taiyo Yuden Co., Ltd. | Piezoelectric device with piezoelectric ceramic layer constituted by alkali-containing niobate type perovskite composition |
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