JP3993395B2 - Piezoelectric ceramic, manufacturing method thereof, and piezoelectric element - Google Patents

Description

【００４１】
続いて、例えば、この仮焼物をボールミルにより湿式粉砕し仮焼成粉とした（ステップＳ１０２）。そののち、この仮焼成粉に、第２副成分の原料である酸化ビスマス粉末を表１に示した組成となるように添加して混合した（ステップＳ１０３）。表１における第２副成分の種類は第１副成分と同様に酸化物で表示してあり、その含有量も主成分１ｍｏｌの質量に対する値を酸化物に換算したものである。仮焼成粉に第２副成分を添加したのち、乾燥し、ポリビニールアルコール系のバインダーを加えて造粒を行い、２０００ｋｇ／ｃｍ² の圧力で円柱状に成形した（ステップＳ１０４）。
【００４２】
成形したのち、この成形体を、酸素濃度８０％以上の雰囲気中において、表１に示した１１００℃以上１１６０℃以下の焼成温度で２時間〜４時間焼成した（ステップＳ１０５）。そののち、得られた焼結体を高さ７．５ｍｍ、直径３ｍｍの円柱状に加工し、円柱の両端面に銀の電極を形成し、１５０℃のシリコーンオイル中で２．５ｋＶ／ｍｍの電圧を印加して分極処理を行った（ステップＳ１０６）。これにより、実施例１−１〜１−３の圧電磁器を得た。
【００４３】
得られた実施例１−１〜１−３の圧電磁器について、アルキメデス法により密度ρｓを求めた。また、インピーダンスアナライザーにより素子静電容量ｃ、共振周波数ｆｒおよび反共振周波数ｆａを測定し、それらの結果から圧電歪定数ｄ₃₃を求めた。更に、熱分析装置によりキュリー温度Ｔｃを測定した。それらの結果を表２に示す。
【００４４】
【表２】

【００４５】
また、本実施例に対する比較例１−１〜１−４として、組成および焼成温度を表１に示したように変えたことを除き、本実施例と同様にして圧電磁器を作製した。なお、比較例１−１は、化５におけるｘ、すなわちランタンの置換量が０．０３未満、化５におけるｙ、すなわちチタンの組成が０．４８よりも大きいものであり、比較例１−２は、ｙが０．４８よりも大きいものである。比較例１−３は、ｘが０．０７よりも大きく、ｙが０．３８未満のものであり、比較例１−４は、ｙが０．３８未満のものである。比較例１−１〜１−４についても、本実施例と同様にして、密度ρｓ、圧電歪定数ｄ₃₃およびキュリー温度Ｔｃをそれぞれ測定した。それらの結果を表２にあわせて示す。
【００４６】
表２に示したように、実施例１−１〜１−３によれば、いずれも、７．８Ｍｇ／ｍ³ 以上の密度ρｓ、６００ｐＣ／Ｎ以上の圧電歪定数ｄ₃₃および２００℃以上のキュリー温度Ｔｃが得られた。これに対して、ｘが０．０３未満の比較例１−１およびｙが０．４８よりも大きい比較例１−２では、圧電歪定数ｄ₃₃が６００ｐＣ／Ｎ未満であり、ｘが０．０７よりも大きい比較例１−３では、密度ρｓが７．８Ｍｇ／ｍ³ 未満、キュリー温度Ｔｃが２００℃未満であった。また、ｙが０．３８未満の比較例１−４では、圧電歪定数ｄ₃₃が６００ｐＣ／Ｎ未満であった。
【００４７】
すなわち、ランタンを化５におけるｘが０．０３≦ｘ≦０．０７の範囲内で含むようにすれば、密度ρｓ、圧電歪定数ｄ₃₃およびキュリー温度Ｔｃをいずれも高くできることが分かった。また、化５においてｙで表されるチタンの組成を０．３８≦ｙ≦０．４８の範囲内とするようにすれば、圧電歪定数を向上させることができるこことが分かった。
【００４８】
（実施例２−１，２−２）
実施例２−１，２−２として、組成および焼成温度を表３に示したように変えたことを除き、実施例１−１〜１−３と同様にして圧電磁器を作製した。なお、実施例２−１では、第１副成分としてニオブに代えてタンタルを添加し、原料には酸化タンタル粉末を用いた。また、本実施例に対する比較例２−１，２−２として、組成および焼成温度を表３に示したように変えたことを除き、本実施例と同様にして圧電磁器を作製した。なお、比較例２−１は第１副成分を添加しないものであり、比較例２−２は主成分１ｍｏｌの質量に対する第１副成分の含有量を酸化物に換算して１．８質量％よりも多くしたものである。
【００４９】
【表３】

【００５０】
これら実施例２−１，２−２および比較例２−１，２−２についても、実施例１−１〜１−３と同様にして、密度ρｓ、圧電歪定数ｄ₃₃およびキュリー温度Ｔｃをそれぞれ測定した。それらの結果を表４に示す。
【００５１】
【表４】

【００５２】
表４に示したように、実施例２−１，２−２によれば、いずれも、７．８Ｍｇ／ｍ³ 以上の密度ρｓ、６００ｐＣ／Ｎ以上の圧電歪定数ｄ₃₃および２００℃以上のキュリー温度Ｔｃが得られた。これに対して、第１副成分を含まない比較例２−１では圧電歪定数ｄ₃₃が６００ｐＣ／Ｎ未満であり、第１副成分の含有量が多い比較例２−２では密度ρｓが７．８Ｍｇ／ｍ³ 未満、圧電歪定数ｄ₃₃が６００ｐＣ／Ｎ未満であった。
【００５３】
すなわち、第１副成分を、主成分１ｍｏｌの質量に対して、酸化物に換算して０．３質量％以上１．８質量％以下の範囲内で含有するようにすれば、密度ρｓおよびキュリー温度Ｔｃを高く保持しつつ、圧電歪定数ｄ₃₃をより向上させることができるこことが分かった。
【００５４】
（実施例３−１〜３−６）
実施例３−１〜３−６として、組成および焼成温度を表５に示したように変えたことを除き、実施例１−１〜１−３と同様にして圧電磁器を作製した。なお、その際、第１副成分の種類を表５に示したように変化させ、原料には酸化アンチモン粉末，酸化タンタル粉末および酸化ニオブ粉末のいずれか１種または２種を用いた。
【００５５】
【表５】

【００５６】
これら実施例３−１〜３−６についても、実施例１−１〜１−３と同様にして、密度ρｓ、圧電歪定数ｄ₃₃およびキュリー温度Ｔｃをそれぞれ測定した。それらの結果を表６に示す。
【００５７】
【表６】

【００５８】
表６に示したように、実施例３−１〜３−６によれば、いずれも、７．８Ｍｇ／ｍ³ 以上の密度ρｓ、６００ｐＣ／Ｎ以上の圧電歪定数ｄ₃₃および２００℃以上のキュリー温度Ｔｃが得られた。すなわち、第１副成分として、アンチモン，ニオブおよびタンタルからなる群のうちの少なくとも１種を含むようにすれば、密度ρｓおよびキュリー温度Ｔｃを高く保持しつつ、圧電歪定数ｄ₃₃をより向上させることができるこことが分かった。
【００５９】
（実施例４−１，４−２）
実施例４−１，４−２として、組成および焼成温度を表７に示したように変えたことを除き、実施例１−１〜１−３と同様にして圧電磁器を作製した。なお、実施例４−１では、第１副成分としてニオブに代えてタンタルを添加し、原料には酸化タンタル粉末を用いた。また、本実施例に対する比較例４−１，４−２として、組成および焼成温度を表７に示したように変えたことを除き、本実施例と同様にして圧電磁器を作製した。なお、比較例４−１では、実施例４−１と同様に、第１副成分としてニオブに代えてタンタルを添加し、原料には酸化タンタル粉末を用いた。比較例４−１は第２副成分を添加しないものであり、比較例４−２は主成分１ｍｏｌの質量に対する第２副成分の含有量を酸化物に換算して１．５質量％よりも多くしたものである。
【００６０】
【表７】

【００６１】
これら実施例４−１，４−２および比較例４−１，４−２についても、実施例１−１〜１−３と同様にして、密度ρｓ、圧電歪定数ｄ₃₃およびキュリー温度Ｔｃをそれぞれ測定した。それらの結果を表８に示す。
【００６２】
【表８】

【００６３】
表８に示したように、実施例４−１，４−２によれば、いずれも、７．８Ｍｇ／ｍ³ 以上の密度ρｓ、６００ｐＣ／Ｎ以上の圧電歪定数ｄ₃₃および２００℃以上のキュリー温度Ｔｃが得られた。これに対して、第２副成分を含まない比較例４−１では、１２００℃未満の焼成温度では十分な焼結性を得ることができず、圧電歪定数ｄ₃₃は６００ｐＣ／Ｎ未満であった。また、第２副成分の含有量が多い比較例４−２では１２００℃未満の焼成温度では焼結が難しく、密度ρｓ，圧電歪定数ｄ₃₃およびキュリー温度Ｔｃのいずれについても不十分な値しか得られなかった。
【００６４】
すなわち、第２副成分を、主成分１ｍｏｌの質量に対して、酸化物に換算して０．１質量％以上１．５質量％以下の範囲内で含有するようにすれば、焼成温度を低くしても、密度ρｓ、圧電歪定数ｄ₃₃およびキュリー温度Ｔｃのいずれについても高い値を得られることが分かった。
【００６５】
（比較例５−１〜５−３）
比較例５−１として、ランタンの原料として酸化ランタン（Ｌａ₂ Ｏ₃ ）粉末を用いたことを除き、他は実施例１−１と同様にして圧電磁器を作製した。また、比較例５−２として、ジルコニウムの原料として用いる酸化ジルコニウム粉末の比表面積を２０ｍ² ／ｇとしたことを除き、他は実施例１−１と同様にして圧電磁器を作製した。更に、比較例５−３として、焼成時の雰囲気を大気中としたことを除き、他は実施例１−１と同様にして圧電磁器を作製した。
【００６６】
これら比較例５−１，５−３についても、実施例１−１と同様にして、密度ρｓおよび圧電歪定数ｄ₃₃をそれぞれ測定した。それらの結果を実施例１−１の結果と共に表９に示す。また、比較例５−２についても、実施例１−１と同様にして圧電歪定数ｄ₃₃を測定した。その結果を実施例１−１の結果と共に図４に示す。
【００６７】
【表９】

【００６８】
表９に示したように、実施例１−１によれば、焼成温度を１１３０℃としても７．８Ｍｇ／ｍ³ 以上の密度ρｓおよび６００ｐＣ／Ｎ以上の圧電歪定数ｄ₃₃が得られた。これに対して、水酸化ランタンを用いない比較例５−１および酸素分圧が低い雰囲気中で焼成した比較例５−３では、焼成温度を低くすることが可能でも、１１３０℃の低温では十分な焼結性を得ることができず、密度ρｓは７．８Ｍｇ／ｍ³ 未満であり、圧電歪定数ｄ₃₃も６００ｐＣ／Ｎ未満であった。
【００６９】
また、図４に示したように、比表面積が小さい酸化ジルコニウム粉末を用いた比較例５−２では、焼成温度を低くすることが可能でも、１１３０℃の低温では６００ｐＣ／Ｎ未満の圧電歪定数ｄ₃₃しか得られなかった。
【００７０】
すなわち、ランタンの原料として水酸化ランタンを用いるようにすれば、または、酸素濃度８０％以上の雰囲気中において焼成するようにすれば、密度ρｓおよび圧電歪定数ｄ₃₃を高く保持しつつ、焼成温度をより低くできることが分かった。また、ジルコニウムの原料として比表面積が３０ｍ² ／ｇ以上の酸化ジルコニウム粉末を用いるようにすれば、圧電歪定数ｄ₃₃を高く保持しつつ、焼成温度をより低くできることが分かった。
【００７１】
なお、上記実施例では、いくつかの例を挙げて具体的に説明したが、主成分および副成分の組成を上記実施の形態で説明した範囲内で変化させても、同様の結果を得ることができる。
【００７２】
以上、実施の形態および実施例を挙げて本発明を説明したが、本発明は、上記実施の形態および実施例に限定されるものではなく、種々変形することができる。例えば、上記実施の形態および実施例では、化５に示した主成分と、第１副成分と、第２副成分とを含有する場合について説明したが、これらに加えて、他の成分を含んでいてもよい。その場合、その他の成分は、第１副成分および第２副成分と同様に主成分に固溶していてもよく、または固溶していなくてもよい。
【００７３】
【発明の効果】
以上説明したように、請求項１記載の圧電磁器または請求項７記載の圧電素子によれば、化１に示した酸化物を主成分とし、第１副成分としてアンチモン，ニオブおよびタンタルからなる群のうちの少なくとも１種を所定量含有すると共に、第２副成分としてビスマスを所定量含有するようにしたので、密度，圧電歪定数およびキュリー温度を高く保持しつつ、焼成温度を低くすることができる。よって、焼成後のそりあるいはうねりを低減することができ、焼成治具との反応も抑制することができる。また、積層型の圧電素子についても容易に形成することもできる。従って、容易に量産を図ることができる。
【００７４】
また、請求項２ないし請求項６のいずれか１項に記載の圧電磁器の製造方法によれば、化２に示した主成分を構成する元素と共に、第１副成分であるアンチモン，ニオブおよびタンタルからなる群のうちの少なくとも１種を所定量含有し、第２副成分であるビスマスを所定量含有する混合物を焼成するようにしたので、本発明の圧電磁器を容易に得ることができる。
【００７５】
特に、請求項４ないし請求項６のいずれか１項に記載の圧電磁器の製造方法によれば、ランタンの原料として水酸化ランタンを用いるようにしたので、低温でも焼結性を向上させることができ、密度および圧電歪定数を高く保持しつつ、焼成温度をより低くすることができる。
【００７６】
また、請求項５または請求項６に記載の圧電磁器の製造方法によれば、ジルコニウムの原料として比表面積が３０ｍ² ／ｇ以上の酸化ジルコニウム粉末を用いるようにしたので、圧電歪定数を高く保持しつつ、焼成温度をより低くすることができると共に、比表面積が５０ｍ² ／ｇ以下の酸化ジルコニウム粉末を用いるようにしたので、粉体の取り扱いを容易とすることができ、容易に製造することができる。
【００７７】
更に、請求項２記載の圧電磁器の製造方法によれば、酸素濃度８０％以上の雰囲気中で焼成するようにしたので、低温でも焼結性を向上させることができ、密度および圧電歪定数を高く保持しつつ、焼成温度をより低くすることができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る圧電磁器の製造方法を表す流れ図である。
【図２】本発明の一実施の形態に係る圧電磁器を用いた圧電素子の一構成例を表す斜視図である。
【図３】本発明の一実施の形態に係る圧電磁器を用いた圧電素子の他の一構成例を表す断面図である。
【図４】実施例１−１と実施例５−２との圧電歪定数を比較して表す特性図である。
【符号の説明】
１…圧電基板、１ａ，１ｂ…対向面、２，３…電極、１０…積層体、１１…圧電層、１２…内部電極、２１，２２…端子電極。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric ceramic suitable for an actuator, a piezoelectric buzzer, a sounding body, a sensor, and the like, a manufacturing method thereof, and a piezoelectric element.
[0002]
[Prior art]
Conventionally, as a piezoelectric ceramic used for an actuator or the like, lead titanate (PbTiO 2) is used._ThreePT) and lead zirconate (PbZrO)_ThreeA solid solution (PZT) system with PZ) is known to be suitable, and various improvements have been made depending on the application. For example, antimony oxide (Sb₂O_Five), Niobium oxide (Nb)₂O_Five) Or tungsten oxide (WO_Three) Or the like, lead (Pb) partially substituted with barium (Ba), strontium (Sr), calcium (Ca), lanthanum (La), or the like, or niobium nickel acid as the third component Lead (Pb (Ni_1/3Nb_2/3) O_Three) Or niobium lead magnesium oxide (Pb (Mg_1/3Nb_2/3) O_Three) And other complex perovskato compounds have been reported.
[0003]
In addition, as a piezoelectric ceramic for an actuator, for example, a piezoelectric strain constant d in a thickness longitudinal vibration mode₃₃Is required to be a high value of 600 pC / N or more. However, conventionally, a high piezoelectric strain constant d₃₃In general, a piezoelectric ceramic having a low Curie temperature of less than 200 ° C. has a practical problem. For example, the piezoelectric strain constant d₃₃When the temperature exceeds 600 pC / N, the Curie temperature is around 100 ° C., and the device operating temperature is limited to near room temperature. In addition, since the piezoelectric ceramic for the actuator requires fine processing, it is required that there are almost no pores, that is, a high density. However, conventionally, the piezoelectric strain constant d₃₃In a piezoelectric ceramic having a thickness exceeding 600 pC / N, a sufficiently high density could not be obtained.
[0004]
Therefore, in order to solve these problems, the present applicant replaced a part of lead of PZT with lanthanum and used tin oxide (SnO) as a subcomponent.₂) Has been proposed (see JP-A-10-95665). According to this piezoelectric ceramic, density, piezoelectric strain constant d₃₃Both the Curie temperature and the Curie temperature can be sufficiently high.
[0005]
[Problems to be solved by the invention]
However, the piezoelectric ceramic described in JP-A-10-95665 has a problem that the optimum firing temperature is as high as around 1280 ° C. and mass production is difficult.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and an object thereof is a piezoelectric ceramic having a dense and high piezoelectric strain constant and a Curie temperature and capable of being fired at a low temperature, a manufacturing method thereof, and a piezoelectric element. Is to provide.
[0007]
[Means for Solving the Problems]
  The piezoelectric ceramic according to the present invention contains the oxide shown in chemical formula 3 as a main component, and is composed of antimony (Sb), niobium (Nb), and tantalum (Ta) as the first subcomponent with respect to 1 mol of the main component. At least one member of the group consisting of oxide (Sb₂ O_Three , Nb₂ O_Five , Ta₂ O_Five ) In the range of 0.3 mass% or more and 1.8 mass% or less, and bismuth (Bi) is added as an oxide (Bi) as the second subcomponent with respect to 1 mol of the main component.₂ O_Three ) 0.1% by mass or more in terms of0.6Contained within the mass% rangeIn addition, lanthanum hydroxide as a raw material for lanthanum (La) and a specific surface area of 30 m as a raw material for zirconium (Zr) ² / G or more 50m ² / G or less of zirconium oxide is used, and is fired in an atmosphere having an oxygen concentration of 80% or more..
[Chemical 3]
(Pb_1-xLa_x ) [Zr_1-yTi_y ]_{1-x / 4}O_Three
(Wherein x is 0.03 ≦ x ≦0.045, Y is0.44It is a value within a range satisfying ≦ y ≦ 0.48. )
[0008]
In the piezoelectric ceramic according to the present invention, the oxide shown in Chemical formula 3 is the main component, and at least one member selected from the group consisting of antimony, niobium and tantalum is included as the first subcomponent. Strain constant and Curie temperature are obtained. Moreover, since bismuth is included as the second subcomponent, the firing temperature can be lowered.
[0009]
  The method for manufacturing a piezoelectric ceramic according to the present invention includes at least one element selected from the group consisting of antimony, niobium, and tantalum, which are the first subcomponents, together with the elements constituting the main component shown in Chemical Formula 4, with a mass of 1 mol of the main component Against the oxide (Sb₂ O_Three , Nb₂ O_Five , Ta₂ O_Five ) In a range of 0.3% by mass or more and 1.8% by mass or less, and bismuth as the second subcomponent with respect to the mass of 1 mol of the main component, oxide (Bi₂ O_Three ) 0.1% by mass or more in terms of0.6A step of molding and firing a mixture containing within a mass% or less rangeLanthanum hydroxide as a raw material of lanthanum (La), specific surface area of 30 m as a raw material of zirconium (Zr) ² / G or more 50m ² / G or less of zirconium oxide is used, and the firing step is performed in an atmosphere having an oxygen concentration of 80% or more.Is.
[Formula 4]
  (Pb_1-xLa_x ) [Zr_1-yTi_y ]_{1-x / 4}O_Three
(Wherein x is 0.03 ≦ x ≦0.045, Y is0.44It is a value within a range satisfying ≦ y ≦ 0.48. )
[0010]
In the method for manufacturing a piezoelectric ceramic according to the present invention, the element constituting the main component shown in Chemical Formula 4, at least one selected from the group consisting of antimony, niobium and tantalum as the first subcomponent, and the second subcomponent Since a mixture containing certain bismuth is molded and fired, a piezoelectric ceramic having a dense and high piezoelectric strain constant and a Curie temperature can be obtained even when fired at a low temperature.
[0012]
The piezoelectric element according to the present invention uses the piezoelectric ceramic according to the present invention.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0014]
A piezoelectric ceramic according to an embodiment of the present invention contains the oxide shown in Chemical formula 5 as a main component.
[Chemical formula 5]
(Pb_1-xLa_x) [Zr_1-yTi_y]_{1-x / 4}O_Three
In the formula, x is a value within a range satisfying 0.03 ≦ x ≦ 0.07 and y is satisfying 0.38 ≦ y ≦ 0.48. Note that the composition of zirconium and titanium with respect to lead and lanthanum and the composition of oxygen are determined stoichiometrically and may deviate from the stoichiometric composition.
[0015]
This oxide is one in which a part of lead in lead zirconate titanate is replaced by lanthanum, whereby the piezoelectric strain constant d₃₃Can be increased to 600 pC / N or more, for example. The substitution amount of lanthanum, that is, x in chemical formula 5 is set to 0.03 or more and 0.07 or less because if it is less than 0.03, the effect of improving the piezoelectric strain constant cannot be sufficiently obtained. If the density is exceeded, for example, the density is 7.8 Mg / m^ThreeThis is because the Curie temperature also drops below 200 ° C., for example. Further, the ratio of zirconium to titanium, that is, y in the chemical formula 5 is set to 0.38 or more and 0.48 or less, outside this range, for example, a high piezoelectric strain constant d of 600 pC / N or more.₃₃Because you can't get.
[0016]
This piezoelectric ceramic also contains at least one of the group consisting of antimony, niobium and tantalum as an oxide (Sb) as the first subcomponent with respect to the mass of 1 mol of the main component shown in Chemical formula 5.₂O_Three, Nb₂O_Five, Ta₂O_Five) In terms of 0.3 to 1.8% by mass. Thus, in this piezoelectric ceramic, the piezoelectric strain constant d₃₃Can be further improved. When the content of the first subcomponent is 0.3% by mass or more and 1.8% by mass or less in terms of oxide with respect to 1 mol of the main component, it is less than 0.3% by mass. Piezoelectric strain constant d₃₃Cannot be sufficiently improved, and if it exceeds 1.8 mass%, the density and the piezoelectric strain constant d₃₃It is because it will fall. The first subcomponent is dissolved in the main component oxide, and is present at a position where so-called B site of lead zirconate titanate, that is, titanium and zirconium can exist.
[0017]
The piezoelectric ceramic further uses bismuth as an oxide (Bi) as the second subcomponent with respect to the mass of 1 mol of the main component shown in Chemical formula 5.₂O_Three) In terms of 0.1 to 1.5% by mass. Thus, in this piezoelectric ceramic, the density and the piezoelectric strain constant d₃₃In addition, the firing temperature can be lowered while keeping the Curie temperature high. The content of the second subcomponent is 0.1% by mass or more and 1.5% by mass or less in terms of oxide with respect to 1 mol of the main component at a low temperature of less than 0.1% by mass. It is not possible to obtain sufficient sinterability, so that the piezoelectric strain constant d₃₃When the content exceeds 1.5% by mass, sintering becomes difficult, so that the density and piezoelectric strain constant d₃₃This is because the Curie temperature is lowered. The second subcomponent is also dissolved in the main component oxide in the same manner as the first subcomponent, and is present at the position where the so-called B site of lead zirconate titanate, that is, titanium and zirconium can exist. Yes.
[0018]
A piezoelectric ceramic having such a configuration can be manufactured, for example, as follows.
[0019]
FIG. 1 is a flowchart showing a method of manufacturing the piezoelectric ceramic. First, as raw materials for elements constituting the main component, for example, lead oxide (PbO) powder, titanium oxide (TiO 2)₂) Powder, zirconium oxide (ZrO)₂) Powder and lanthanum hydroxide (La (OH)_Three) Prepare powder. Moreover, as a raw material of the first subcomponent, for example, antimony oxide (Sb₂O_Three) Powder, niobium oxide (Nb)₂O_Five) Powder and tantalum oxide (Ta₂O_Five) Prepare at least one of the group consisting of powders. Note that these raw materials may be oxides instead of oxides, such as carbonates, oxalates or hydroxides, which become oxides upon firing.
[0020]
However, lanthanum hydroxide is used as the lanthanum raw material, and the zirconium raw material has a particle diameter of 1 μm or less and a specific surface area of 30 m.²/ G or more 50m²/ G or less of zirconium oxide powder is preferably used. By using lanthanum hydroxide, the sinterability can be improved, so that a sufficient piezoelectric strain constant d can be achieved even if the firing temperature is lowered.₃₃It is because it can obtain. The specific surface area is 30m²/ G or more of the zirconium oxide powder allows sufficient piezoelectric strain constant d even when the firing temperature is lowered.₃₃While the specific surface area is 50 m.²This is because when the amount exceeds / g, it is difficult to handle the powder, synthesis becomes difficult, and it is not practical.
[0021]
Next, after sufficiently drying these raw materials, the final composition is weighed so as to be in the above range, thoroughly mixed in an organic solvent or water with a ball mill or the like, dried, press-molded, Calcination is performed at 950 ° C. for 2 to 8 hours (step S101). Subsequently, for example, the calcined product is sufficiently pulverized in an organic solvent or water by a ball mill or the like to obtain a calcined powder containing the main component and the first subcomponent (step S102). After that, for example, bismuth oxide (Bi) prepared separately as a raw material for the second subcomponent is added to the calcined powder.₂O_Three) Add and mix the powder so that the final composition is in the above range (step S103). The second subcomponent, that is, the raw material of bismuth, may be added at the time of mixing before temporary firing, in which case it is not oxidized but oxidized by firing like carbonate, oxalate or hydroxide. You may use what becomes a thing.
[0022]
  After adding the second subcomponent to the calcined powder, the mixture is dried, and granulated by adding a polyvinyl alcohol binder, for example, using a uniaxial press molding machine or a hydrostatic pressure molding machine (CIP) Press molding (step S104). After the molding, for example, the compact is fired at a low temperature of less than 1200 ° C., preferably 1100 ° C. or more and less than 1200 ° C. for 2 hours to 6 hours (step S105). At that time, the firing atmosphereOxygen concentration80% or more is preferable.Oxygen concentrationIf the temperature is low, sufficient density cannot be obtained unless the firing temperature is increased.₃₃It is because it will also fall.
[0023]
After firing, the obtained sintered body is polished as necessary, provided with a polarization electrode, and subjected to polarization treatment by applying an electric field in heated silicone oil (step S106). After that, the above-mentioned piezoelectric ceramic is obtained by removing the electrode for polarization.
[0024]
Such a piezoelectric ceramic is preferably used as a material for a piezoelectric element such as an actuator, a piezoelectric buzzer, a sounding body, and a sensor, particularly as a material for an actuator.
[0025]
FIG. 2 shows a configuration example of a piezoelectric element using the piezoelectric ceramic according to the present embodiment. The piezoelectric element includes a piezoelectric substrate 1 made of the piezoelectric ceramic according to the present embodiment, and a pair of electrodes 2 and 3 provided on a pair of opposing surfaces 1a and 1b of the piezoelectric substrate 1, respectively. The piezoelectric substrate 1 is polarized, for example, in the thickness direction, that is, in the direction opposite to the electrodes 2 and 3, and when a voltage is applied through the electrodes 2 and 3, the piezoelectric substrate 1 comes to vibrate in the thickness direction. Yes.
[0026]
The electrodes 2 and 3 are made of metal such as gold (Au), for example, and are respectively provided on the entire opposing surfaces 1 a and 1 b of the piezoelectric substrate 1. An external power source (not shown) is electrically connected to the electrodes 2 and 3 via, for example, a wire (not shown).
[0027]
This piezoelectric element can be manufactured by a conventional method. For example, first, a piezoelectric ceramic is manufactured as described above, and then processed into a predetermined size as necessary to form the piezoelectric substrate 1. Next, the electrodes 2 and 3 are deposited on the piezoelectric substrate 1, for example, to obtain the piezoelectric element shown in FIG.
[0028]
FIG. 3 shows another configuration example of the piezoelectric element using the piezoelectric ceramic according to the present embodiment. The piezoelectric element includes, for example, a laminate 10 in which a plurality of piezoelectric layers 11 and a plurality of internal electrodes 12 made of the piezoelectric ceramic according to the present embodiment are alternately laminated. The thickness per layer of the piezoelectric layer 11 is preferably about 1 μm to 100 μm, for example, and the number of stacked layers of the piezoelectric layer 11 is determined according to the target displacement.
[0029]
The internal electrode 12 contains a conductive material. The conductive material is not particularly limited, but for example, at least one selected from the group consisting of silver (Ag), gold (Au), platinum (Pt), and palladium (Pd), or an alloy thereof is preferable. In addition, the internal electrode 12 may contain about 0.1% by mass or less of various trace components such as phosphorus (P) in addition to these. The thickness of the internal electrode 12 is preferably about 0.5 μm to 3 μm, for example. If the thickness is less than 0.5 μm, the internal electrode 12 is interrupted, and sufficient piezoelectric characteristics cannot be obtained. If the thickness is more than 3 μm, distortion of the laminated body 10 after firing increases.
[0030]
For example, the internal electrodes 12 are alternately extended in opposite directions, and a pair of terminal electrodes 21 and 22 electrically connected to the internal electrode 12 are provided in the extending direction. The terminal electrodes 21 and 22 are formed, for example, by baking terminal electrode paste. This terminal electrode paste contains, for example, a conductive material, glass frit, and a vehicle. The conductive material includes, for example, at least one selected from the group consisting of silver, gold, copper, nickel, palladium, and platinum. Examples of the vehicle include an organic vehicle and an aqueous vehicle. The organic vehicle is obtained by dissolving a binder in an organic solvent, and the aqueous vehicle is obtained by dissolving a water-soluble binder and a dispersant in water. The thicknesses of the terminal electrodes 21 and 22 are appropriately determined according to the application and the like, but are usually about 10 μm to 50 μm.
[0031]
This piezoelectric element can be manufactured as follows, for example. First, a pre-fired powder is formed in the same manner as in the piezoelectric ceramic manufacturing method described above, and a second subcomponent and a vehicle are added thereto and kneaded to prepare a piezoelectric layer paste. Next, the above-described conductive material for forming the internal electrode 12 or various oxides, organometallic compounds, resinates, or the like that become the above-described conductive material after firing are kneaded with a vehicle to prepare an internal electrode paste. Note that additives such as a dispersant, a plasticizer, a dielectric material, and an insulator material may be added to the internal electrode paste as necessary.
[0032]
  Subsequently, using these piezoelectric layer paste and internal electrode paste, a green chip which is a precursor of the laminate 10 is manufactured by, for example, a printing method or a sheet method. After that, a binder removal process is performed, and the laminate 10 is formed by firing. The atmosphere at the time of firing is, for example, similar to the above-described method for manufacturing a piezoelectric ceramic,Oxygen concentrationIs preferably 80% or more, and the firing temperature is preferably a low temperature of less than 1200 ° C.
[0033]
After forming the laminated body 10, end face polishing is performed by, for example, barrel polishing or sand blasting, and the terminal electrode paste prepared in the same manner as the internal electrode paste is printed or transferred and baked to form the terminal electrodes 21 and 22. . Thereby, the piezoelectric element shown in FIG. 3 is obtained.
[0034]
As described above, according to the present embodiment, the oxide shown in Chemical Formula 5 is a main component, and a predetermined amount of at least one selected from the group consisting of antimony, niobium, and tantalum is contained as the first subcomponent. Since a predetermined amount of bismuth is contained as two subcomponents, density, piezoelectric strain constant d₃₃In addition, the firing temperature can be lowered while keeping the Curie temperature high. Therefore, warpage or undulation after firing can be reduced, and reaction with the firing jig can also be suppressed. Also, a multilayer piezoelectric element as shown in FIG. 3 can be easily formed. Therefore, mass production can be easily achieved.
[0035]
In particular, if lanthanum hydroxide is used as a raw material for lanthanum, the sinterability can be improved even at a low temperature, and the density and piezoelectric strain constant d₃₃The firing temperature can be further lowered while keeping the temperature high.
[0036]
The specific surface area is 30m as a raw material for zirconium.²/ G or more zirconium oxide powder, the piezoelectric strain constant d₃₃The firing temperature can be lowered while maintaining a high value, and the specific surface area is 50 m.²/ G or less of zirconium oxide powder makes it easy to handle the powder and can be easily manufactured.
[0037]
  Furthermore,Oxygen concentrationIf firing is performed in an atmosphere of 80% or more, the sinterability can be improved even at a low temperature, and the density and piezoelectric strain constant d₃₃The firing temperature can be further lowered while keeping the temperature high.
[0038]
【Example】
Further, a specific embodiment of the present invention will be described with reference to FIG.
[0039]
(Examples 1-1 to 1-3)
As Examples 1-1 to 1-3, first, lead oxide powder, titanium oxide powder, zirconium oxide powder and lanthanum hydroxide powder, which are raw materials of the main component, and niobium oxide powder, which is the raw material of the first subcomponent, Prepared. At that time, the zirconium oxide powder has a particle diameter of 1 μm or less and a specific surface area of 35 m.²/ G was used. Next, these raw materials were sufficiently dried and weighed so as to have the composition shown in Table 1, then wet mixed by a ball mill, dried and molded, and calcined at 900 ° C. to 950 ° C. for 2 hours to 4 hours. (Step S101). Note that x and y in Table 1 are those values in Chemical Formula 5, and the type of the first subcomponent is represented by an oxide. Moreover, content of a 1st subcomponent converts the value with respect to the mass of 1 mol of main components into an oxide.
[0040]
[Table 1]

[0041]
Subsequently, for example, the calcined product was wet pulverized by a ball mill to obtain a calcined powder (step S102). After that, bismuth oxide powder, which is a raw material of the second subcomponent, was added to the calcined powder so as to have the composition shown in Table 1 and mixed (step S103). The kind of the 2nd subcomponent in Table 1 is displayed with the oxide similarly to the 1st subcomponent, and the content also converts the value with respect to the mass of 1 mol of main components into the oxide. After adding the second subcomponent to the calcined powder, it is dried, granulated by adding a polyvinyl alcohol binder, 2000 kg / cm²It was molded into a cylindrical shape with a pressure of (Step S104).
[0042]
  After molding this molded body,Oxygen concentrationIn an atmosphere of 80% or more, firing was performed at a firing temperature of 1100 ° C. or higher and 1160 ° C. or lower shown in Table 1 for 2 hours to 4 hours (step S105). After that, the obtained sintered body was processed into a cylindrical shape having a height of 7.5 mm and a diameter of 3 mm, and silver electrodes were formed on both end faces of the cylinder, and 2.5 kV / mm in 150 ° C. silicone oil. Polarization processing was performed by applying a voltage (step S106). Thereby, the piezoelectric ceramics of Examples 1-1 to 1-3 were obtained.
[0043]
For the obtained piezoelectric ceramics of Examples 1-1 to 1-3, the density ρs was determined by the Archimedes method. Further, the element capacitance c, the resonance frequency fr, and the antiresonance frequency fa are measured by an impedance analyzer, and the piezoelectric strain constant d is determined from the results.₃₃Asked. Furthermore, the Curie temperature Tc was measured with a thermal analyzer. The results are shown in Table 2.
[0044]
[Table 2]

[0045]
Further, as Comparative Examples 1-1 to 1-4 for this example, piezoelectric ceramics were produced in the same manner as in this example, except that the composition and the firing temperature were changed as shown in Table 1. In Comparative Example 1-1, x in Chemical Formula 5, that is, the amount of substitution of lanthanum is less than 0.03, and y in Chemical Formula 5, that is, the composition of titanium is larger than 0.48. Comparative Example 1-2 Where y is greater than 0.48. In Comparative Example 1-3, x is greater than 0.07 and y is less than 0.38, and in Comparative Example 1-4, y is less than 0.38. For Comparative Examples 1-1 to 1-4 as well, the density ρs and the piezoelectric strain constant d are the same as in this example.₃₃The Curie temperature Tc was measured. The results are also shown in Table 2.
[0046]
As shown in Table 2, according to Examples 1-1 to 1-3, all are 7.8 Mg / m.^ThreeDensity ρs above, piezoelectric strain constant d above 600 pC / N₃₃A Curie temperature Tc of 200 ° C. or higher was obtained. In contrast, in Comparative Example 1-1 where x is less than 0.03 and Comparative Example 1-2 where y is greater than 0.48, the piezoelectric strain constant d₃₃In Comparative Example 1-3 where x is less than 600 pC / N and x is greater than 0.07, the density ρs is 7.8 Mg / m.^ThreeThe Curie temperature Tc was less than 200 ° C. In Comparative Example 1-4 where y is less than 0.38, the piezoelectric strain constant d₃₃Was less than 600 pC / N.
[0047]
That is, if x in the chemical formula 5 is included in the range of 0.03 ≦ x ≦ 0.07, the density ρs, the piezoelectric strain constant d₃₃It was also found that both the Curie temperature Tc can be increased. Further, it was found that the piezoelectric strain constant can be improved if the composition of titanium represented by y in the chemical formula 5 is in the range of 0.38 ≦ y ≦ 0.48.
[0048]
(Examples 2-1 and 2-2)
As Examples 2-1 and 2-2, piezoelectric ceramics were produced in the same manner as in Examples 1-1 to 1-3, except that the composition and the firing temperature were changed as shown in Table 3. In Example 2-1, tantalum was added instead of niobium as the first subcomponent, and tantalum oxide powder was used as a raw material. Further, as Comparative Examples 2-1 and 2-2 for this example, piezoelectric ceramics were produced in the same manner as in this example, except that the composition and the firing temperature were changed as shown in Table 3. In addition, Comparative Example 2-1 does not add the first subcomponent, and Comparative Example 2-2 converts the content of the first subcomponent with respect to the mass of 1 mol of the main component to 1.8% by mass in terms of oxide. More than that.
[0049]
[Table 3]

[0050]
Also in Examples 2-1 and 2-2 and Comparative Examples 2-1 and 2-2, the density ρs and the piezoelectric strain constant d are the same as those in Examples 1-1 to 1-3.₃₃The Curie temperature Tc was measured. The results are shown in Table 4.
[0051]
[Table 4]

[0052]
As shown in Table 4, according to Examples 2-1 and 2-2, both were 7.8 Mg / m.^ThreeDensity ρs above, piezoelectric strain constant d above 600 pC / N₃₃A Curie temperature Tc of 200 ° C. or higher was obtained. On the other hand, in Comparative Example 2-1, which does not include the first subcomponent, the piezoelectric strain constant d₃₃Is less than 600 pC / N, and in Comparative Example 2-2 where the content of the first subcomponent is large, the density ρs is 7.8 Mg / m.^ThreeLess than, piezoelectric strain constant d₃₃Was less than 600 pC / N.
[0053]
That is, if the first subcomponent is contained in the range of 0.3% by mass to 1.8% by mass in terms of oxide with respect to 1 mol of the main component, the density ρs and the Curie While maintaining the temperature Tc high, the piezoelectric strain constant d₃₃It was found that can be further improved.
[0054]
(Examples 3-1 to 3-6)
As Examples 3-1 to 3-6, piezoelectric ceramics were produced in the same manner as in Examples 1-1 to 1-3, except that the composition and the firing temperature were changed as shown in Table 5. At that time, the type of the first subcomponent was changed as shown in Table 5, and any one or two of antimony oxide powder, tantalum oxide powder and niobium oxide powder was used as a raw material.
[0055]
[Table 5]

[0056]
Also in Examples 3-1 to 3-6, as in Examples 1-1 to 1-3, the density ρs and the piezoelectric strain constant d₃₃The Curie temperature Tc was measured. The results are shown in Table 6.
[0057]
[Table 6]

[0058]
As shown in Table 6, according to Examples 3-1 to 3-6, all are 7.8 Mg / m.^ThreeDensity ρs above, piezoelectric strain constant d above 600 pC / N₃₃A Curie temperature Tc of 200 ° C. or higher was obtained. That is, if at least one member selected from the group consisting of antimony, niobium and tantalum is included as the first subcomponent, the piezoelectric strain constant d is maintained while keeping the density ρs and the Curie temperature Tc high.₃₃It was found that can be further improved.
[0059]
(Examples 4-1 and 4-2)
As Examples 4-1 and 4-2, piezoelectric ceramics were produced in the same manner as in Examples 1-1 to 1-3, except that the composition and the firing temperature were changed as shown in Table 7. In Example 4-1, tantalum was added instead of niobium as the first subcomponent, and tantalum oxide powder was used as a raw material. Moreover, as comparative examples 4-1 and 4-2 for this example, a piezoelectric ceramic was produced in the same manner as in this example, except that the composition and the firing temperature were changed as shown in Table 7. In Comparative Example 4-1, as in Example 4-1, tantalum was added instead of niobium as the first subcomponent, and tantalum oxide powder was used as a raw material. In Comparative Example 4-1, the second subcomponent is not added, and in Comparative Example 4-2, the content of the second subcomponent with respect to the mass of 1 mol of the main component is less than 1.5% by mass in terms of oxide. A lot.
[0060]
[Table 7]

[0061]
Also in Examples 4-1 and 4-2 and Comparative Examples 4-1 and 4-2, the density ρs and the piezoelectric strain constant d are the same as those in Examples 1-1 to 1-3.₃₃The Curie temperature Tc was measured. The results are shown in Table 8.
[0062]
[Table 8]

[0063]
As shown in Table 8, according to Examples 4-1 and 4-2, both were 7.8 Mg / m.^ThreeDensity ρs above, piezoelectric strain constant d above 600 pC / N₃₃A Curie temperature Tc of 200 ° C. or higher was obtained. On the other hand, in Comparative Example 4-1, which does not include the second subcomponent, sufficient sinterability cannot be obtained at a firing temperature of less than 1200 ° C., and the piezoelectric strain constant d₃₃Was less than 600 pC / N. Further, in Comparative Example 4-2 in which the content of the second subcomponent is large, sintering is difficult at a firing temperature of less than 1200 ° C., and density ρs, piezoelectric strain constant d₃₃Insufficient values were obtained for both the Curie temperature Tc and the Curie temperature Tc.
[0064]
That is, if the second subcomponent is contained within a range of 0.1% by mass or more and 1.5% by mass or less in terms of oxide with respect to 1 mol of the main component, the firing temperature is lowered. Even so, density ρs, piezoelectric strain constant d₃₃It was found that high values can be obtained for both the Curie temperature Tc and the Curie temperature Tc.
[0065]
(Comparative example5-1 to 5-3)
  Comparative exampleAs 5-1 lanthanum oxide (La₂ O_Three A piezoelectric ceramic was produced in the same manner as in Example 1-1 except that powder was used. Also,Comparative exampleAs 5-2, the specific surface area of the zirconium oxide powder used as a raw material of zirconium is 20 m.² A piezoelectric ceramic was produced in the same manner as in Example 1-1 except that / g was used. Furthermore,Comparative exampleAs 5-3, a piezoelectric ceramic was produced in the same manner as in Example 1-1 except that the atmosphere during firing was in the air.
[0066]
  theseComparative exampleFor 5-1 and 5-3, as in Example 1-1, the density ρs and the piezoelectric strain constant d₃₃Was measured respectively. The results are shown in Table 9 together with the results of Example 1-1. Also,Comparative exampleFor 5-2, as in Example 1-1, the piezoelectric strain constant d₃₃Was measured. The result is shown in FIG. 4 together with the result of Example 1-1.
[0067]
[Table 9]

[0068]
  As shown in Table 9, according to Example 1-1, even if the firing temperature was 1130 ° C., 7.8 Mg / m^Three The above density ρs and the piezoelectric strain constant d of 600 pC / N or more₃₃was gotten. In contrast, lanthanum hydroxide is not usedComparative exampleBaked in an atmosphere having a low oxygen partial pressure and 5-1.Comparative example5-3, even if the firing temperature can be lowered, sufficient sinterability cannot be obtained at a low temperature of 1130 ° C., and the density ρs is 7.8 Mg / m.^Three And the piezoelectric strain constant d₃₃Was less than 600 pC / N.
[0069]
  Further, as shown in FIG. 4, zirconium oxide powder having a small specific surface area was used.Comparative exampleIn 5-2, although the firing temperature can be lowered, the piezoelectric strain constant d of less than 600 pC / N at a low temperature of 1130 ° C.₃₃Only obtained.
[0070]
  That is, if lanthanum hydroxide is used as a raw material of lanthanum, orOxygen concentrationIf firing is performed in an atmosphere of 80% or more, density ρs and piezoelectric strain constant d₃₃It has been found that the firing temperature can be further lowered while keeping the temperature high. The specific surface area is 30m as a raw material for zirconium.² / G or more zirconium oxide powder, the piezoelectric strain constant d₃₃It has been found that the firing temperature can be further lowered while keeping the temperature high.
[0071]
In the above examples, some examples have been specifically described. However, similar results can be obtained even when the composition of the main component and the subcomponent is changed within the range described in the above embodiment. Can do.
[0072]
The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above embodiments and examples, the case where the main component shown in Chemical Formula 5, the first subcomponent, and the second subcomponent are contained has been described, but in addition to these, other components are included. You may go out. In that case, other components may be dissolved in the main component in the same manner as the first subcomponent and the second subcomponent, or may not be dissolved.
[0073]
【The invention's effect】
As described above, according to the piezoelectric ceramic according to claim 1 or the piezoelectric element according to claim 7, the group consisting of the oxide shown in chemical formula 1 as a main component and antimony, niobium and tantalum as the first subcomponent. In addition to containing a predetermined amount of at least one of them, and a predetermined amount of bismuth as the second subcomponent, it is possible to lower the firing temperature while keeping the density, the piezoelectric strain constant and the Curie temperature high. it can. Therefore, warpage or undulation after firing can be reduced, and reaction with the firing jig can also be suppressed. A multilayer piezoelectric element can also be easily formed. Therefore, mass production can be easily achieved.
[0074]
Further, according to the method for manufacturing a piezoelectric ceramic according to any one of claims 2 to 6, together with the elements constituting the main component shown in chemical formula 2, antimony, niobium and tantalum which are the first subcomponents Since the mixture containing a predetermined amount of at least one of the group consisting of bismuth as the second subcomponent is fired, the piezoelectric ceramic of the present invention can be easily obtained.
[0075]
In particular, according to the method for manufacturing a piezoelectric ceramic according to any one of claims 4 to 6, since lanthanum hydroxide is used as a raw material of lanthanum, sinterability can be improved even at a low temperature. The firing temperature can be further lowered while maintaining the density and the piezoelectric strain constant high.
[0076]
Moreover, according to the method for manufacturing a piezoelectric ceramic according to claim 5 or 6, the specific surface area of the raw material for zirconium is 30 m.²/ G or more zirconium oxide powder is used, so that the firing temperature can be lowered while keeping the piezoelectric strain constant high, and the specific surface area is 50 m.²/ G or less of zirconium oxide powder is used, so that the powder can be handled easily and can be manufactured easily.
[0077]
  Further claims2According to the piezoelectric ceramic manufacturing method described,Oxygen concentrationSince the firing is performed in an atmosphere of 80% or more, the sinterability can be improved even at a low temperature, and the firing temperature can be further lowered while keeping the density and the piezoelectric strain constant high.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a method of manufacturing a piezoelectric ceramic according to an embodiment of the present invention.
FIG. 2 is a perspective view illustrating a configuration example of a piezoelectric element using a piezoelectric ceramic according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating another configuration example of a piezoelectric element using a piezoelectric ceramic according to an embodiment of the present invention.
FIG. 4 is a characteristic diagram showing a comparison of piezoelectric strain constants between Example 1-1 and Example 5-2.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Piezoelectric substrate, 1a, 1b ... Opposite surface, 2, 3 ... Electrode, 10 ... Laminated body, 11 ... Piezoelectric layer, 12 ... Internal electrode, 21, 22 ... Terminal electrode.

Claims (4)

The main component is the oxide shown in Chemical Formula 1,
With respect to the mass of 1 mol of the main component, at least one of the group consisting of antimony (Sb), niobium (Nb) and tantalum (Ta) is used as the first subcomponent in the form of oxide (Sb ₂ O ₃ , Nb ₂ O ₅ and Ta ₂ O ₅ in terms of being contained within a range of 0.3 mass% or more and 1.8 mass% or less,
Bismuth (Bi) is converted into oxide (Bi ₂ O ₃ ) as the second subcomponent with respect to 1 mol of the main component, and contained within a range of 0.1% by mass to 0.6 % by mass. And
Further, lanthanum hydroxide as a raw material of lanthanum (La) and a specific surface area of 30 m ² as a raw material of zirconium (Zr) / G or more 50m ² A piezoelectric ceramic characterized in that it is fired in an atmosphere having an oxygen concentration of 80% or more, each using zirconium oxide of / g or less .

(In the formula, x is a value within a range satisfying 0.03 ≦ x ≦ 0.045 and y is satisfying 0.44 ≦ y ≦ 0.48.) In addition to the elements constituting the main component shown in Chemical Formula 2, at least one member selected from the group consisting of antimony (Sb), niobium (Nb) and tantalum (Ta), which are the first subcomponents, has a mass of 1 mol of the main component. On the other hand, it is contained in the range of 0.3% by mass or more and 1.8% by mass or less in terms of oxides (Sb ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ ), and is the second subcomponent. A mixture containing bismuth (Bi) in the range of 0.1% by mass or more and 0.6 % by mass or less in terms of oxide (Bi ₂ O ₃ ) with respect to 1 mol of the main component is molded. Including the step of firing
Lanthanum hydroxide as a raw material of lanthanum (La), specific surface area of 30 m ² as a raw material of zirconium (Zr) / G or more 50m ² / G or less of zirconium oxide, and the firing step is performed in an atmosphere having an oxygen concentration of 80% or more .

(In the formula, x is a value within a range satisfying 0.03 ≦ x ≦ 0.045 and y is satisfying 0.44 ≦ y ≦ 0.48.) Preparing a pre-fired powder containing a main component and a first subcomponent;
The method for producing a piezoelectric ceramic according to claim 2, further comprising: adding a second subcomponent to the temporarily fired powder.   A piezoelectric element using the piezoelectric ceramic according to claim 1.

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