JP4817481B2

JP4817481B2 - Piezoelectric member

Info

Publication number: JP4817481B2
Application number: JP2000230274A
Authority: JP
Inventors: 歩松元
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2000-07-31
Filing date: 2000-07-31
Publication date: 2011-11-16
Anticipated expiration: 2020-07-31
Also published as: JP2002043645A

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric member exhibiting essential piezoelectric characteristics of piezoelectric ceramic body by suppressing machining flaw or microcrack occurring on the surface through grinding or polishing and preventing the extent of polarization from lowering due to machining pressure or heat. SOLUTION: In the piezoelectric member 1 where each surface of a piezoelectric ceramic body 2 is ground or polished and electrodes 3 and 3 provided on the opposite machined surfaces are subjected to polarization, the ratio (A/B) between the peak diffraction intensity A of a tetragonal system 200 and the peak diffraction intensity B of a tetragonal system 002 measured on the upper and lower surfaces 2a and 2a perpendicular to the direction of polarization by X ray diffraction is 1.5 or less. The ratio (B/A) between the peak diffraction intensity B of the tetragonal system 002 and the peak diffraction intensity A of the tetragonal system 200 measured on the surface 2b at the side part parallel with the direction of polarization by X ray diffraction is 1.5 or less.

Description

【０００１】
【発明の属する技術分野】
本発明は、圧電ブザー、圧電センサー、加速度センサー、発振子、共振子、着火素子、超音波振動子、インクジェット記録ヘッドや超音波モーター等に用いられる圧電アクチュエータ、振動ジャイロ等を構成する圧電部材に関するものである。
【０００２】
【従来の技術】
従来、圧電ブザー、圧電センサー、加速度センサー、発振子、共振子、着火素子、超音波振動子、インクジェット記録ヘッドや超音波モーター等に用いられる圧電アクチュエータ、振動ジャイロ等には、例えば板厚方向に分極処理された板状の圧電セラミック体の上下面に電極を形成した圧電部材が用いられている。
【０００３】
このような圧電部材は、板状の圧電セラミック体に研削や研磨等の加工を施して所定の寸法形状とした後、圧電セラミック体の上下面に印刷法、イオンプレーティング法、真空蒸着法、スパッタリング法、ＰＶＤ法、ＣＶＤ法、メッキ法等の膜形成手段にて電極をそれぞれ被着し、次いで上下の電極間に通電して圧電セラミック体を板厚方向に分極処理することにより製作されていた。また、上記圧電部材を複数個積層して構成した積層型の圧電部材も知られている。
【０００４】
【発明が解決しようとする課題】
しかしながら、圧電部材を製作するにあたり、板状の圧電セラミック体の上下面や側面に研削や研磨等の加工を施すと、加工圧力や加工熱が作用することによって圧電セラミック体の上下面や側面を構成する結晶に歪みが発生し、分極処理によってある一定方向に歪んでいた結晶軸が伸縮し、この結晶軸の伸縮によって分極の度合いが小さくなり、電気機械結合係数が低下するため、電気的エネルギーから機械的エネルギーへの変換効率あるいは逆のエネルギー変換効率が悪いといった課題があった。
【０００５】
【課題を解決するための手段】
そこで、本発明は上記課題に鑑み、表面の全てが、研削加工と研磨加工との少なくとも一方が施されて加工表面とされた圧電セラミック体であって、少なくとも一対の対向する表面にそれぞれ電極を備え、上記電極間に分極処理を施した圧電部材において、上記加工表面は、分極方向に対して垂直な表面と分極方向に平行な表面とからなり、分極方向に対して垂直な表面である上記加工表面においては、上記加工表面をＸ線回折にて測定した時の正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂとの比（Ａ／Ｂ）を１．５以下とし、分極方向に平行な表面である上記加工表面においては、上記加工表面をＸ線回折にて測定した時の正方晶００２回折のピーク強度Ｂと正方晶２００回折のピーク強度Ａとの比（Ｂ／Ａ）を１．５以下としたことを特徴とする。
【０００６】
【発明の実施の形態】
以下、本発明の実施形態について説明する。
【０００７】
図１は本発明の圧電部材の一例を示す図で、（ａ）はその一部を破断した斜視図、（ｂ）は断面図である。
【０００８】
この圧電部材１は、円板状をした圧電セラミック体２の上下の表面２ａ，２ａに電極３，３を形成したもので、各電極３，３を形成する上下の表面２ａ，２ａには平滑かつ平坦な表面とするために研削加工や研磨加工を施すとともに、圧電セラミック体２の側部の表面２ｂには所定の形状とするために研削加工や研磨加工を施してあり、上下の電極３，３間の板厚方向に分極処理を施してある。そして、上下の電極３，３間にパルス電圧を印加すると、圧電セラミック体２には板厚方向に伸縮する振動と放射方向に伸縮する振動が発生するため、例えば、圧電ブザー、超音波振動子、インクジェット記録ヘッドや超音波モータ等に用いられる圧電アクチュエータ、振動ジャイロとして用いることができ、また、上記圧電部材１に外力が作用すると、圧電セラミック体２内に電流が流れ、上下の電極３，３間にて電気的変化を検出することができるため、例えば、圧電センサーや加速度センサーとして用いることができる。
【０００９】
このような圧電セラミック体２の材質としては、チタン酸ジルコン酸鉛（ＰＺＴ系）、マグネシウムニオブ酸鉛（ＰＭＮ系）、ニッケルニオブ酸鉛（ＰＮＮ系）等を主成分とする圧電セラミックスを用いることができ、また、圧電セラミック板２の上下の表面２ａ，２ａに形成する電極３，３の材質としては、金、銀、銅、白金、ニッケル、クロム、アルミニウム、スズ、パラジウム等の金属あるいはこれらの合金を用いることができる。
【００１０】
そして、本発明の圧電部材１は、表面の全てが、研削と研磨等との少なくとも一方の加工が施されて加工表面とされた圧電セラミック体２であって、少なくとも一対の対向する表面にそれぞれ電極を備え、この電極間に分極処理を施した圧電部材１において、加工表面は、分極方向に対して垂直な表面と分極方向に平行な表面とからなり、分極方向に対して垂直な表面である加工表面においては、この圧電セラミック体２の上下面２ａ，２ａをそれぞれＸ線回折にて測定した時の正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂとの比（Ａ／Ｂ）が１．５以下であり、分極方向に平行な表面である加工表面においては、圧電セラミック体２の側面２ｂをＸ線回折にて測定した時の正方晶００２回折のピーク強度Ｂと正方晶２００回折のピーク強度Ａとの比（Ｂ／Ａ）が１．５以下であることを特徴とし、好ましくはいずれの加工表面におけるピーク強度比も１．０以下、さらに好ましくはいずれの加工表面におけるピーク強度比も０．９以下であることが良い。
【００１１】
即ち、本件発明者は圧電部材１の開発にあたり、分極処理を施した圧電セラミック体２に研削や研磨等の加工を施すと、加工前後において電気機械結合係数等の圧電特性が低下し、また、研削や研磨等の加工を施した後に分極処理を施しても圧電セラミック体２が持つ本来の電気機械結合係数を得ることができないことを知見した。
【００１２】
この現象は、分極処理前の圧電セラミックスを構成する結晶粒子は自発分極がランダムに配列された分域構造を持ち、自発分極のベクトル総和がゼロで、焼結された圧電セラミック全体では等方性を呈しているのであるが、分極処理を施すために板厚方向に直流電界をかけると、各結晶粒子の分域が一定の方向に揃って歪みを生じ、直流電界をかけることを止めても電界方向に残留分域が存在して極性を示し、圧電性を示すようになる。
【００１３】
しかしながら、分極処理した圧電セラミック体２に研削や研磨等の加工を施すと、大きな加工圧力が作用したり、加工熱が発生し、加工表面に存在する結晶に歪みが発生して結晶軸が伸縮するため、予め分極処理により発生していたある一定方向の歪みが解消されて分極の度合いが小さくなるために加工前後で電気機械結合係数等の圧電特性が低下することに起因するものと思われる。
【００１４】
また、研削や研磨等の加工を施した後に分極処理を施しても本来の電気機械結合係数等の圧電特性が得られないのは、加工によって加工表面に加工傷やマイクロクラックが発生すると、その後に分極処理を施すための直流電界をかけても、加工傷やマイクロクラックが発生した結晶粒内の各分域が一定の方向に揃わないため、本来の圧電特性を発揮できないものと思われる。
【００１５】
そこで、圧電セラミック体２が持つ本来の圧電特性が得られるようにするため種々研究を重ねたところ、電気機械結合係数等の圧電特性と圧電セラミック体２の加工表面に存在する結晶のＸ線回折強度との間には相関があり、加工表面が分極方向に対して垂直な表面（圧電セラミック体２の上下の表面２ａ，２ａ）である時には、その加工表面をそれぞれＸ線回折にて測定した時の正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂとの比（Ａ／Ｂ）が大きくなるほど電気機械結合係数の値が小さくなり、また、加工表面が分極方向と平行な表面（圧電セラミック体２の側部の表面２ｂ）である時には、その加工表面をＸ線回折にて測定した時の正方晶００２回折のピーク強度Ｂと正方晶２００回折のピーク強度Ａとの比（Ｂ／Ａ）が大きくなるほど電気機械結合係数の値が小さくなることを知見し、電気機械結合係数の低下を抑える最適な条件について実験を繰り返したところ、加工表面が分極方向に対して垂直な表面（圧電セラミック体２の上下の表面２ａ，２ａ）である時には、その加工表面をＸ線回折にて測定した時の正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂとの比（Ａ／Ｂ）を１．５以下とし、また、加工表面が分極方向と平行な表面（圧電セラミック体２の側部の表面２ｂ）である時には、その加工表面をＸ線回折にて測定した時の正方晶００２回折のピーク強度Ｂと正方晶２００回折のピーク強度Ａとの比（Ｂ／Ａ）を１．５以下とすれば良いことを見出し、本発明に至った。
【００１６】
なお、正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂとの比（Ａ／Ｂ）あるいは正方晶００２回折のピーク強度Ｂと正方晶２００回折のピーク強度Ａとの比（Ｂ／Ａ）を測定するにあたっては、理学製のＲＩＮＴ１４００Ｖ型のＸ線回折を行い、Ｘ線源をＣｕ、Ｘ線源の管電圧を５０ｋＶ、管電流を２００ｍＡとして２軸の縦型ゴニオメータにてステップ幅を０．０２０°とし、回折角度４０°〜５０°の範囲に現れる正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂを測定することにより算出すれば良い。
【００１７】
また、Ｘ線回折装置を用いれば、測定物の表面から３０μｍ程度の深度までの結晶状態を確認することができるため、圧電セラミック体２の上下面２ａ，２ａに形成する電極３，３の厚さが３０μｍ未満であれば、電極３，３上から直接測定することもでき、この場合、事前に電極３，３単独での回折角度４０°〜５０°の範囲におけるピーク強度を確認しておき、この電極３，３単独のピーク強度を除く補正を行えば良い。
【００１８】
ただし、Ｘ線回折のピーク強度比を上述した範囲とするには、研削や研磨等の加工を施した圧電セラミック体２の上下の表面２ａ，２ａ及び側部の表面２ｂを、算術平均粗さ（Ｒａ）で０．３μｍ以下、最大高さ（Ｒｙ）で３．０μｍ以下の平滑面とすることが必要である。
【００１９】
即ち、圧電セラミック体２の各表面２ａ，２ａ，２ｂにおける表面粗さが算術平均粗さ（Ｒａ）で０．３μｍを超えるか、あるいは最大高さ（Ｒｙ）が３．０μｍを超えると、各表面２ａ，２ａ，２ｂには大きな加工傷やマイクロクラックが存在し、この加工傷やマイクロクラックの発生により、分極処理を施しても加工傷やマイクロクラックが存在する領域の結晶の歪みをある一定方向に揃わせることができず、また、予め分極処理を施している場合には、各表面２ａ，２ａ，２ｂにおいてある一定方向に揃っていた歪みが解消されて分極の度合いが低下するため、いずれの場合においても圧電セラミック体２が持つ本来の圧電特性を発揮させることができないからである。
【００２０】
ところで、図１に示す圧電部材１を製造するには、まず、チタン酸ジルコン酸鉛（ＰＺＴ系）、マグネシウムニオブ酸鉛（ＰＭＮ系）、ニッケルニオブ酸鉛（ＰＮＮ系）等を主成分とする圧電セラミック体２を用意する。そして、この圧電セラミック体２を所定の寸法となるように研削や研磨等の加工を施して円板状とする。例えば、平面研削盤や両面ラップ盤等を用いて厚み加工を行い、円筒研削盤やダイシングソー等を用いて外辺の加工を行うことにより、圧電セラミック体２の上下の表面２ａ，２ａ及び側部の表面２ｂの表面粗さを算術平均粗さ（Ｒａ）で０．３μｍ以下、最大高さ（Ｒｙ）で３．０μｍ以下とする。そして、圧電セラミック体２の上下の表面２ａ，２ａに、金、銀、銅、ニッケル、白金、ニッケル、クロム、アルミニウム、スズ、パラジウム等の金属あるいはこれらの合金を、印刷法、イオンプレーティング法、真空蒸着法、スパッタリング法、ＰＶＤ法、ＣＶＤ法、メッキ法等の周知の薄膜形成手段により被着して電極３，３を形成し、しかる後、両電極３，３間に直流電界をかけて円板状をした圧電セラミック体２の板厚方向に分極処理を施すことにより得ることができるのであるが、厚み加工を施すにあたり、平面研削盤を用いる場合には、番手が＃６００（砥粒の粒径２０〜３０μｍ）〜＃３０００（砥粒の粒径２〜６μｍ）のダイヤモンド砥石を、また、両面ラップ盤を用いる場合には、番手が＃１０００（砥粒の粒径８〜２０μｍ）〜＃４０００（砥粒の粒径２〜４μｍ）のメッシュで分級されたＳｉＣやＡｌ₂Ｏ₃、ダイヤモンド等の砥粒を、円筒研削盤やダイシングソーにて外辺の加工を施す場合には、粒径４〜２０μｍ程度のダイヤモンド砥粒を固着したダイヤモンドホイールやダイヤモンドブレードをそれぞれ用い、かつ加工速度を１５ｍｍ／ｓｅｃ以下、好ましくは５ｍｍ／ｓｅｃ程度として加工することが必要である。
【００２１】
即ち、厚み加工におけるダイヤモンド砥石の番手が＃６００（砥粒の粒径２０〜３０μｍ）未満であったり、砥粒が＃１０００（砥粒の粒径８〜２０μｍ）未満であったり、外辺加工におけるダイヤモンド砥粒の粒径が２０μｍを超えると、圧電セラミック板２の表面２ａ，２ａ，２ｂを算術平均粗さ（Ｒａ）で０．３μｍ以下、最大高さ（Ｒｙ）で３．０μｍ以下とすることができず、表面２ａ，２ａ，２ｂに大きな加工傷やマイクロクラックが多数発生するからであり、厚み加工におけるダイヤモンド砥石の番手が＃３０００（砥粒の粒径２〜６μｍ）を超えたり、砥粒が＃４０００（砥粒の粒径２〜４μｍ）を超えたり、外辺加工におけるダイヤモンド砥粒の粒径が４μｍ未満であると、表面２ａ，２ａ，２ｂを上述した表面粗さとすることができたとしても加工に時間がかかり過ぎて作業効率が悪いからである。また、これらの加工速度が１５ｍｍ／ｓｅｃを超えると、圧電セラミック体２に大きな加工圧力が作用するとともに、高い加工熱が発生するため、分極の度合いが低下することを防止することができなくなるからである。
【００２２】
その為、平面研削盤に用いるダイヤモンド砥石の番手は＃６００（砥粒の粒径２０〜３０μｍ）〜＃３０００（砥粒の粒径２〜６μｍ）、両面ラップ盤に用いる砥粒の番手は＃１０００（砥粒の粒径８〜２０μｍ）〜＃４０００（砥粒の粒径２〜４μｍ）、円筒研削盤やダイシングソーに用いるダイヤモンドホイールやダイヤモンドブレードに固着されたダイヤモンド砥粒の粒径は４〜２０μｍの範囲のものを用いるとともに、加工速度１５ｍｍ／ｓｅｃ以下の条件にて加工すれば良い。
【００２４】
また、図１では、一つの圧電セラミック体２の対向する表面に電極３，３を形成した圧電部材１について説明したが、上記圧電部材１を複数個積み重ねて形成した積層型の圧電部材にも適用することができ、本発明の要旨を逸脱しない範囲であれば改良や変更できることは言う迄もない。
【００２５】
【実施例】
（実施例１）
ここで、図１の圧電部材１を製作するにあたり、圧電セラミック体２に研削加工を施して各加工表面における表面粗さと、各加工表面のピーク強度比を異ならせた時の研削加工前後における電気機械結合係数の低下率を測定する実験を行った。
【００２６】
具体的には、圧電セラミック体２を製作するため、原料粉末として、Ｐｂ₃Ｏ₄、ＺｒＯ₂、ＴｉＯ₂、ＳｒＣＯ₃、ＢａＣＯ₃、ＺｎＯ、Ｓｂ₂Ｏ₃、ＮｉＯ、ＴｅＯ₂、Ｎｂ₂Ｏ₅を用意し、それぞれの金属元素のモル比率が、Ｐｂ：０．９４、Ｚｒ：０．４７、Ｔｉ：０．４５、Ｓｒ：０．０４、Ｂａ：０．０２、Ｚｎ：０．０２５、Ｓｂ：０．０５、Ｎｉ：０．００２５、Ｔｅ：０．００２５となるように秤量したものに溶媒として水を加え、ボールミルにて２０時間湿式混合した。次にこの混合物を乾燥し、８００℃の温度で３時間熱処理を加えて仮焼粉体を製作し、この仮焼粉体に水とＺｒＯ₂製のボールを加えてボールミルにて２０時間、湿式混合粉砕し、さらに有機バインダーを添加、混練した後乾燥させて造粒粉を作製し、１．５×１０⁸Ｎ／ｍ²の成形圧で、φ２０ｍｍ×２ｍｍの円板状体に成形して脱脂処理した後、１２４０℃前後の温度で焼成することにより、φ１６ｍｍ×１．６ｍｍの円板状をした圧電セラミック体２を作製した。
【００２７】
次に、得られた圧電セラミック体２の上下面に、銀とガラス成分からなる分極用の電極層を焼付けによって形成し、８０℃のシリコンオイル中で直流電圧を３０分印加し、３．０ｋＶ／ｍｍの電界にて分極処理を行った後、１５０℃恒温の中で２ｈｒのエージング処理を行った。
【００２８】
次いで、分極用の電極層を取り除いた後、圧電セラミック体２の厚み加工と外辺の加工を行った。ここでは、φ１５ｍｍ×０．５ｍｍの寸法とするため、番手が＃４００（砥粒の粒径３０〜４０μｍ）、＃６００（砥粒の粒径２０〜３０μｍ）、＃１０００（砥粒の粒径８〜２０μｍ）、＃２０００（砥粒の粒径４〜８μｍ）、＃３０００（砥粒の粒径２〜６μｍ）、＃４０００（砥粒の粒径２〜４μｍ）の６種類のＳｉＣ砥粒を用いて両面ラップ盤にて厚み加工を施し、また、粒径範囲が３０〜４０μｍ、２０〜３０μｍ、８〜２０μｍ、４〜６μｍ、２〜６μｍのダイヤモンド砥粒をそれぞれ固着したダイヤモンドホイールを用いて円筒研削盤にて外辺の加工を行った。
【００２９】
そして、得られた圧電セラミック体２の上下の表面２ａ，２ａ及び側部の表面２ｂの表面粗さを、小坂研究所製のサーフコーダーＳＥ−２３００と呼ばれる表面粗さ測定器を用い、ＪＩＳＢ０６０１−１９９４に準拠して各加工表面２ａ，２ａ，２ｂの算術平均粗さ（Ｒａ）と最大高さ（Ｒｙ）を各々測定するとともに、圧電セラミック体２の上下の表面２ａ，２ａにおける正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂとの比（Ａ／Ｂ）、及び圧電セラミック体２の側部の表面２ｂにおける正方晶００２回折のピーク強度Ｂと正方晶２００回折のピーク強度Ａとの比（Ｂ／Ａ）を、理学製のＲＩＮＴ１４００Ｖ型のＸ線回折装置を行い、Ｘ線源をＣｕ、Ｘ線源の管電圧を５０ｋＶ、管電流を２００ｍＡとして２軸の縦型ゴニオメータにてステップ幅を０．０２０°とし、回折角度４０°から５０°の範囲に現れる正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂをそれぞれ測定した後、その比率を算出することにより求めた。
【００３０】
しかる後、加工を施した圧電セラミック体２の上下の表面２ａ，２ａに銀とガラス成分からなる銀ペーストを塗布し、焼付けによって電極層を形成することにより試料としての圧電部材１を製作し、各試料を形成する円板状をした圧電セラミック体２の放射方向の振動における電気機械結合係数Ｋｐを日本電子工業学会規格ＥＭＡＳ−６１００に準拠して行った。
【００３１】
また、上述した試料と同一組成、同一条件にて焼成することにより、焼成したままの寸法がφ１５ｍｍ×０．５ｍｍである圧電セラミック体２を製作し、この圧電セラミック体２の上下の表面に銀とガラス成分とからなる電極層を焼付けによって形成した後、同様の条件にて分極処理したものを基準試料として用意し、この基準試料を形成する円板状をした圧電セラミック体２の放射方向の振動における電気機械結合係数Ｋｐを日本電子工業学会規格ＥＭＡＳ−６１００に準拠して行い、該基準試料の電気機械結合係数Ｋｐに対する上記各試料の電気機械結合係数Ｋｐの比率を、加工前後における電気機械結係数Ｋｐの低下率として測定し、この低下率が５％未満であるものを優れたものと評価した。
【００３２】
結果は表１に示す通りである。
【００３３】
【表１】

【００３４】
この結果、表１に示すように、試料Ｎｏ．１６〜１９，２２〜２５，２８〜３１および３４〜３７は、圧電セラミック体２の各表面における表面粗さを算術平均粗さ（Ｒａ）で０．３μｍ以下で、かつ最大高さ（Ｒｙ）で３．０μｍ以下とし、かつ加工表面が分極方向に対して垂直な表面（圧電セラミック体の上下面２ａ，２ａ）である時には、その加工表面をＸ線回折にて測定したときの正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂとの比（Ａ／Ｂ）を１．５以下とし、また、加工表面が分極方向に対して平行な表面（圧電セラミック体２の側面２ｂ）である時には、その加工表面をＸ線回折にて測定したときの正方晶００２回折のピーク強度Ｂと正方晶２００回折のピーク強度Ａとの比（Ｂ／Ａ）を１．５以下としてあることから、各加工表面には大きな加工傷やマイクロクラックが殆どなく、加工前後における電気機械結合係数Ｋｐの低下率を５％未満に抑えることができ、優れていた。
【００３５】
特に、試料Ｎｏ．２９〜３１および３５〜３７のように、各加工表面におけるピーク強度の比を１．０以下とすることにより、加工前後における電気機械結合係数Ｋｐの低下率を２％未満に抑えることができ、さらに試料Ｎｏ．３５〜３７のように、各加工表面におけるピーク強度の比を０．９以下とすることにより、加工前後における電気機械結合係数Ｋｐの低下率を１％未満とすることができ、圧電セラミック体２が持つ本来の電気機械結合係数が得られることが判る。
【００３６】
【発明の効果】
以上のように、本発明によれば、表面の全てが、研削加工と研磨加工との少なくとも一方が施されて加工表面とされた圧電セラミック体であって、少なくとも一対の対向する表面にそれぞれ電極を備え、上記電極間に分極処理を施した圧電部材において、上記加工表面は、分極方向に対して垂直な表面と分極方向に平行な表面とからなり、分極方向に対して垂直な表面である上記加工表面においては、上記加工表面をＸ線回折にて測定した時の正方晶２００回折のピーク強度Ａと正方晶００２回折のピーク強度Ｂとの比（Ａ／Ｂ）を１．５以下とし、分極方向に平行な表面である上記加工表面においては、上記加工表面をＸ線回折にて測定した時の正方晶００２回折のピーク強度Ｂと正方晶２００回折のピーク強度Ａとの比（Ｂ／Ａ）を１．５以下としたことによって、研削や研磨等の加工によって圧電セラミック体が本来有する電気機械結合係数等の圧電特性が低下することを防止し、電気的エネルギーと機械的エネルギーとの間の変換効率を向上させることができる。
【００３７】
その為、本発明の圧電部材を、圧電ブザー、インクジェット記録ヘッドや超音波モーター等に用いられる圧電アクチュエータ等に用いれば、大きな変位量が得られ、また、圧電センサーや加速度センサー等に用いれば、小さな変化に対しても感度良く検出することができ、さらに発振子や共振子に用いれば、一定の共振周波数特性を有した製品が安定して得られるといった効果を得ることができる。
【図面の簡単な説明】
【図１】本発明に係る圧電部材の一例を示す図で、（ａ）はその一部を破断した斜視図、（ｂ）は断面図である。
【符号の説明】
１：圧電部材２：圧電セラミック体
２ａ：圧電セラミック体の上下の表面
２ｂ：圧電セラミック体の側部の表面
３：電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric member constituting a piezoelectric buzzer, a piezoelectric sensor, an acceleration sensor, an oscillator, a resonator, an ignition element, an ultrasonic vibrator, an inkjet recording head, an ultrasonic motor, and a vibration gyro. Is.
[0002]
[Prior art]
Conventionally, piezoelectric buzzers, piezoelectric sensors, acceleration sensors, oscillators, resonators, ignition elements, ultrasonic vibrators, piezoelectric actuators used for inkjet recording heads, ultrasonic motors, etc. A piezoelectric member in which electrodes are formed on the upper and lower surfaces of a plate-like piezoelectric ceramic body subjected to polarization treatment is used.
[0003]
Such a piezoelectric member is obtained by subjecting a plate-like piezoelectric ceramic body to processing such as grinding and polishing to have a predetermined size and shape, and then printing, ion plating, vacuum evaporation, It is manufactured by depositing electrodes by film forming means such as sputtering, PVD, CVD, plating, etc., and then applying current between the upper and lower electrodes to polarize the piezoelectric ceramic body in the plate thickness direction. It was. In addition, a laminated piezoelectric member constituted by laminating a plurality of the piezoelectric members is also known.
[0004]
[Problems to be solved by the invention]
However, when manufacturing the piezoelectric member, if processing such as grinding or polishing is applied to the upper and lower surfaces and side surfaces of the plate-shaped piezoelectric ceramic body, the upper and lower surfaces and side surfaces of the piezoelectric ceramic body are affected by processing pressure and processing heat. Since the crystal structure is distorted, the crystal axis that has been distorted in a certain direction by the polarization process expands and contracts, and the expansion and contraction of the crystal axis reduces the degree of polarization and decreases the electromechanical coupling coefficient. There is a problem that the conversion efficiency from mechanical energy to mechanical energy or the reverse energy conversion efficiency is poor.
[0005]
[Means for Solving the Problems]
The present invention has been made in consideration of the above problems, all surface, a piezoelectric ceramic body at least one of which is a decorated with by processing the surface of the polishing and grinding, respectively on opposite surfaces of at least a pair of electrodes And the processed surface is a surface perpendicular to the polarization direction and a surface perpendicular to the polarization direction. In the processed surface, the ratio (A / B) between the peak intensity A of tetragonal 200 diffraction and the peak intensity B of tetragonal 002 diffraction when the processed surface is measured by X-ray diffraction is 1.5 or less. , in the working surface is a surface parallel to a separatory pole direction, the ratio of the tetragonal 002 diffraction peak intensity B and the peak intensity a tetragonal 200 diffraction when measuring the working surface by X-ray diffraction ( B / A) is 1 Wherein the 5 or less were.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0007]
1A and 1B are views showing an example of a piezoelectric member of the present invention, in which FIG. 1A is a perspective view with a part broken away, and FIG.
[0008]
This piezoelectric member 1 has

electrodes

3 and 3 formed on upper and

lower surfaces

2a and 2a of a disk-shaped piezoelectric ceramic body 2, and the upper and

lower surfaces

2a and 2a forming the

electrodes

3 and 3 are smooth. and flat surface and facilities strike the grinding and polishing process to both, on the surface 2b side of the piezoelectric ceramic body 2 has been applied to grinding and polishing to a predetermined shape, the upper and lower Polarization treatment is performed in the thickness direction between the

electrodes

3 and 3. When a pulse voltage is applied between the upper and

lower electrodes

3 and 3, the piezoelectric ceramic body 2 generates vibrations that expand and contract in the thickness direction and vibrations that expand and contract in the radial direction. For example, a piezoelectric buzzer, an ultrasonic vibrator In addition, it can be used as a piezoelectric actuator or a vibration gyro used for an ink jet recording head, an ultrasonic motor, or the like. When an external force acts on the piezoelectric member 1, a current flows in the piezoelectric ceramic body 2, and the upper and lower electrodes 3, Since an electrical change can be detected between the three, it can be used, for example, as a piezoelectric sensor or an acceleration sensor.
[0009]
As a material of the piezoelectric ceramic body 2, a piezoelectric ceramic mainly composed of lead zirconate titanate (PZT), lead magnesium niobate (PMN), lead nickel niobate (PNN), or the like is used. The materials of the

electrodes

3 and 3 formed on the upper and

lower surfaces

2a and 2a of the piezoelectric ceramic plate 2 are metals such as gold, silver, copper, platinum, nickel, chromium, aluminum, tin and palladium, or these These alloys can be used.
[0010]
The piezoelectric member 1 of the present invention is a piezoelectric ceramic body 2 in which the entire surface is subjected to at least one processing such as grinding and polishing to be a processed surface, and each has at least a pair of opposing surfaces. In the piezoelectric member 1 provided with electrodes and subjected to polarization treatment between the electrodes, the processed surface is composed of a surface perpendicular to the polarization direction and a surface parallel to the polarization direction, and is a surface perpendicular to the polarization direction. On a certain processed surface, the ratio of the peak intensity A of tetragonal 200 diffraction to the peak intensity B of tetragonal 002 diffraction (A) when the upper and

lower surfaces

2a and 2a of the piezoelectric ceramic body 2 are measured by X-ray diffraction. / B) is 1.5 or less, and on the processed surface which is a surface parallel to the polarization direction, the peak intensity B of the tetragonal 002 diffraction when the side surface 2b of the piezoelectric ceramic body 2 is measured by X-ray diffraction is Tetragonal The ratio (B / A) to the peak intensity A of 00 diffraction is 1.5 or less, preferably the peak intensity ratio on any processed surface is 1.0 or less, more preferably on any processed surface The peak intensity ratio is also preferably 0.9 or less.
[0011]
That is, in developing the piezoelectric member 1, the present inventor performs processing such as grinding or polishing on the piezoelectric ceramic body 2 that has been subjected to polarization treatment, and the piezoelectric characteristics such as the electromechanical coupling coefficient decrease before and after the processing. It has been found that the original electromechanical coupling coefficient of the piezoelectric ceramic body 2 cannot be obtained even if a polarization treatment is performed after processing such as grinding or polishing.
[0012]
This phenomenon is due to the fact that the crystal particles that make up the piezoelectric ceramic before polarization treatment have a domain structure in which the spontaneous polarization is randomly arranged, the vector sum of the spontaneous polarization is zero, and the sintered piezoelectric ceramic as a whole is isotropic However, if a direct current electric field is applied in the thickness direction in order to carry out the polarization treatment, the domain of each crystal grain is aligned in a certain direction, causing distortion, and even if the direct current electric field is stopped. Residual domains exist in the direction of the electric field, exhibiting polarity and exhibiting piezoelectricity.
[0013]
However, polarization treatment was piezoelectric ceramic body 2 facilities the processing of grinding or polishing or the like to strike, or acts large processing pressure, processing heat is generated, the crystal axis distortion occurs in crystals present in the processing surface It seems to be caused by the fact that the piezoelectric properties such as the electromechanical coupling coefficient decrease before and after the processing because the strain in a certain direction generated in advance by the polarization treatment is eliminated and the degree of polarization is reduced due to expansion and contraction. It is.
[0014]
In addition, even if polarization is applied after processing such as grinding or polishing, the original piezoelectric characteristics such as electromechanical coupling coefficient cannot be obtained. Even if a direct current electric field for applying a polarization treatment is applied, the domains within the crystal grains where the processing flaws and microcracks have occurred are not aligned in a certain direction, so that it seems that the original piezoelectric characteristics cannot be exhibited.
[0015]
Therefore, various studies have been made to obtain the original piezoelectric characteristics of the piezoelectric ceramic body 2, and the piezoelectric characteristics such as the electromechanical coupling coefficient and the X-ray diffraction of crystals existing on the processed surface of the piezoelectric ceramic body 2 are studied. There is a correlation with the strength, and when the processed surface is a surface perpendicular to the polarization direction (upper and

lower surfaces

2a, 2a of the piezoelectric ceramic body 2), the processed surface was measured by X-ray diffraction, respectively. As the ratio (A / B) of the peak intensity A of tetragonal 200 diffraction and the peak intensity B of tetragonal 002 diffraction increases, the value of the electromechanical coupling coefficient decreases and the processed surface is parallel to the polarization direction. When the surface is the surface (surface 2b on the side of the piezoelectric ceramic body 2), the ratio of the peak intensity B of tetragonal 002 diffraction to the peak intensity A of tetragonal 200 diffraction when the processed surface is measured by X-ray diffraction ( It was found that the value of the electromechanical coupling coefficient becomes smaller as / A) becomes larger, and the experiment was repeated on the optimum conditions for suppressing the decrease in the electromechanical coupling coefficient. When it is the upper and

lower surfaces

2a, 2a) of the piezoelectric ceramic body 2, the ratio between the peak intensity A of tetragonal 200 diffraction and the peak intensity B of tetragonal 002 diffraction when the processed surface is measured by X-ray diffraction ( When A / B) is 1.5 or less and the processed surface is a surface parallel to the polarization direction (surface 2b on the side of the piezoelectric ceramic body 2), the processed surface is measured by X-ray diffraction It was found that the ratio (B / A) of the peak intensity B of tetragonal 002 diffraction to the peak intensity A of tetragonal 200 diffraction should be 1.5 or less, and the present invention was achieved.
[0016]
The ratio of the peak intensity A of tetragonal 200 diffraction to the peak intensity B of tetragonal 002 diffraction (A / B) or the ratio of the peak intensity B of tetragonal 002 diffraction to the peak intensity A of tetragonal 200 diffraction (B / A) is measured by RINT1400V X-ray diffraction made by Rigaku, stepped with a biaxial vertical goniometer with Cu as the X-ray source, 50 kV X-ray source tube voltage, and 200 mA tube current. What is necessary is just to calculate by measuring the peak intensity A of the tetragonal crystal 200 diffraction and the peak intensity B of the tetragonal 002 diffraction appearing in the diffraction angle range of 40 ° to 50 ° with the width being 0.020 °.
[0017]
Further, by using the X-ray diffraction apparatus, the surface of the workpiece it is possible to check the crystalline state to 30.mu. m about depth, the piezoelectric ceramic body 2 the upper and lower surfaces 2a, the electrodes 3 to be formed 2a If the thickness is less than 30.mu. m, it can also be measured directly from the

top electrode

3 and 3, in this case, to confirm the peak intensity in the range of diffraction angle 40 ° to 50 ° in advance electrodes 3 alone A correction other than the peak intensity of the

electrodes

3 and 3 may be performed.
[0018]
However, in order to set the peak intensity ratio of the X-ray diffraction within the above-described range, the upper and

lower surfaces

2a and 2a and the side surface 2b of the piezoelectric ceramic body 2 subjected to processing such as grinding and polishing are subjected to arithmetic mean roughness. It is necessary to make the surface smooth (Ra) 0.3 μm or less and maximum height (Ry) 3.0 μm or less.
[0019]
That is, when the surface roughness of each

surface

2a, 2a, 2b of the piezoelectric ceramic body 2 exceeds 0.3 μm in arithmetic mean roughness (Ra) or the maximum height (Ry) exceeds 3.0 μm, The

surface

2a, 2a, 2b has large processing flaws and microcracks. Due to the generation of the processing flaws and microcracks, the crystal distortion in the region where the processing flaws and microcracks are present is constant even if polarization treatment is performed. If the

surface

2a, 2a, 2b has been subjected to polarization treatment in advance, the strains aligned in a certain direction are eliminated and the degree of polarization is reduced. This is because the original piezoelectric characteristics of the piezoelectric ceramic body 2 cannot be exhibited in any case.
[0020]
Incidentally, in order to manufacture the piezoelectric member 1 shown in FIG. 1, first, lead zirconate titanate (PZT system), lead magnesium niobate (PMN system), lead nickel niobate (PNN system) and the like are the main components. A piezoelectric ceramic body 2 is prepared. Then, the piezoelectric ceramic body 2 is processed into a disk shape by grinding or polishing so as to have a predetermined dimension. For example, the upper and

lower surfaces

2a, 2a and sides of the piezoelectric ceramic body 2 are processed by performing thickness processing using a surface grinder, double-sided lapping machine, and the like, and processing the outer side using a cylindrical grinder, dicing saw, or the like. The surface roughness of the surface 2b of the part is 0.3 μm or less in arithmetic mean roughness (Ra) and 3.0 μm or less in maximum height (Ry). Further, a metal such as gold, silver, copper, nickel, platinum, nickel, chromium, aluminum, tin, palladium or an alloy thereof is applied to the upper and

lower surfaces

2a, 2a of the piezoelectric ceramic body 2 by a printing method or an ion plating method. Then,

electrodes

3 and 3 are formed by depositing them by well-known thin film forming means such as vacuum deposition method, sputtering method, PVD method, CVD method and plating method, and then a direct current electric field is applied between both

electrodes

3 and 3 This can be obtained by applying polarization treatment in the plate thickness direction of the piezoelectric ceramic body 2 having a disk shape. When a diamond grindstone having a grain size of 20-30 μm) to # 3000 (abrasive grain size of 2-6 μm) or a double-sided lapping machine is used, the count is # 1000 (abrasive grain size of 8-20 μm). ) - # 4000 (abrasive grains having a grain size of 2-4 [mu] m) of the mesh the classified SiC or Al ₂ O _3, the abrasive grains of diamond or the like, when subjected to processing of the outer sides with a cylindrical grinder to or dicing saw Needs to be processed at a processing speed of 15 mm / sec or less, preferably about 5 mm / sec, using a diamond wheel or diamond blade to which diamond abrasive grains having a particle size of about 4 to 20 μm are fixed.
[0021]
That is, the diamond grindstone count in the thickness processing is less than # 600 (abrasive grain size 20-30 μm), the abrasive grain is less than # 1000 (abrasive grain diameter 8-20 μm), or outer edge processing. When the grain size of the diamond abrasive grains exceeds 20 μm, the

surfaces

2a, 2a, 2b of the piezoelectric ceramic plate 2 are 0.3 μm or less in arithmetic average roughness (Ra) and 3.0 μm or less in maximum height (Ry). This is because the

surface

2a, 2a, 2b has many large processing scratches and micro cracks, and the diamond grindstone count in the thickness processing exceeds # 3000 (abrasive grain size 2-6 μm). When the abrasive grains exceed # 4000 (abrasive grain size 2 to 4 μm) or the diamond abrasive grains in outer edge processing have a grain diameter of less than 4 μm, the

surfaces

2a, 2a, and 2b have the surface roughness described above. thing This is because even if it is possible, the processing takes too much time and the working efficiency is poor. Further, if these processing speeds exceed 15 mm / sec, a large processing pressure acts on the piezoelectric ceramic body 2 and high processing heat is generated, so that it becomes impossible to prevent the degree of polarization from being lowered. It is.
[0022]
Therefore, the diamond grindstone used for the surface grinder is # 600 (abrasive grain size 20-30 μm) to # 3000 (abrasive grain diameter 2-6 μm), and the grinder used for the double-sided lapping machine is # 1000 (abrasive grain size 8-20 μm) to # 4000 (abrasive grain size 2-4 μm), diamond abrasive grains fixed to diamond wheels and diamond blades used in cylindrical grinders and dicing saws have a grain size of 4 What is necessary is just to process on the conditions of 15 mm / sec or less of processing speed while using the thing of the range of -20 micrometers.
[0024]
Further, in FIG. 1, the piezoelectric member 1 in which the

electrodes

3 and 3 are formed on the opposing surfaces of one piezoelectric ceramic body 2 has been described, but a laminated piezoelectric member in which a plurality of the piezoelectric members 1 are stacked is also described. Needless to say, improvements and modifications can be made without departing from the scope of the present invention.
[0025]
【Example】
Example 1
Here, when the piezoelectric member 1 of FIG. 1 is manufactured, the piezoelectric ceramic body 2 is ground and the electric power before and after the grinding process when the surface roughness on each processed surface and the peak intensity ratio of each processed surface are made different. An experiment was conducted to measure the reduction rate of the mechanical coupling coefficient.
[0026]
Specifically, in order to manufacture the piezoelectric ceramic body 2, as raw material powders, Pb ₃ O ₄ , ZrO ₂ , TiO ₂ , SrCO ₃ , BaCO ₃ , ZnO, Sb ₂ O ₃ , NiO, TeO ₂ , Nb ₂ O ₅ and the molar ratio of each metal element is Pb: 0.94, Zr: 0.47, Ti: 0.45, Sr: 0.04, Ba: 0.02, Zn: 0.025, Water was added as a solvent to what weighed so that Sb: 0.05, Ni: 0.0025, and Te: 0.0025, and wet mixed in a ball mill for 20 hours. Next, this mixture is dried and heat treated at a temperature of 800 ° C. for 3 hours to produce a calcined powder. Water and ZrO ₂ balls are added to the calcined powder and wetted in a ball mill for 20 hours. After mixing and pulverizing, adding an organic binder, kneading, and drying to produce granulated powder, forming into a disk-shaped body of φ20 mm × 2 mm with a molding pressure of 1.5 × 10 ⁸ N / m ² After degreasing, the piezoelectric ceramic body 2 having a disk shape of φ16 mm × 1.6 mm was manufactured by firing at a temperature of about 1240 ° C.
[0027]
Next, electrode layers for polarization composed of silver and glass components are formed on the upper and lower surfaces of the obtained piezoelectric ceramic body 2 by baking, and a DC voltage is applied in silicon oil at 80 ° C. for 30 minutes to obtain 3.0 kV. After performing polarization treatment at an electric field of / mm, aging treatment was performed for 2 hours at a constant temperature of 150 ° C.
[0028]
Subsequently, after removing the electrode layer for polarization, the thickness processing of the piezoelectric ceramic body 2 and the processing of the outer side were performed. Here, in order to obtain a size of φ15 mm × 0.5 mm, the counts are # 400 (abrasive grain size 30-40 μm), # 600 (abrasive grain diameter 20-30 μm), # 1000 (abrasive grain diameter) 8 to 20 μm), # 2000 (abrasive grain size 4 to 8 μm), # 3000 (abrasive grain size 2 to 6 μm), # 4000 (abrasive grain size 2 to 4 μm) Using diamond wheels that are processed with thickness using a double-sided lapping machine, and diamond abrasive grains with particle sizes ranging from 30 to 40 μm, 20 to 30 μm, 8 to 20 μm, 4 to 6 μm, and 2 to 6 μm are fixed. Then, the outer side was processed with a cylindrical grinder.
[0029]
Then, the surface roughness of the upper and

lower surfaces

2a, 2a and the side surface 2b of the obtained piezoelectric ceramic body 2 was measured using a surface roughness measuring instrument called Surfcoder SE-2300 manufactured by Kosaka Laboratory, JISB0601- According to 1994, the arithmetic average roughness (Ra) and the maximum height (Ry) of each processed

surface

2a, 2a, 2b are measured, and the tetragonal 200 diffraction on the upper and

lower surfaces

2a, 2a of the piezoelectric ceramic body 2 is measured. The ratio (A / B) between the peak intensity A of the crystal and the peak intensity B of the tetragonal 002 diffraction, and the peak intensity B of the tetragonal 002 diffraction and the peak intensity of the tetragonal 200 diffraction on the surface 2b of the side portion of the piezoelectric ceramic body 2. A ratio (B / A) to A was measured using a RINT1400V X-ray diffractometer manufactured by Rigaku, and the X-ray source was Cu, the tube voltage of the X-ray source was 50 kV, the tube current was 200 mA, and the two-axis longitudinal The step width is set to 0.020 ° with a goniometer, and the peak intensity A of tetragonal 200 diffraction and the peak intensity B of tetragonal 002 diffraction appearing in the diffraction angle range of 40 ° to 50 ° are measured, and then the ratio is calculated. Was determined by
[0030]
Thereafter, a silver paste made of silver and glass components is applied to the upper and

lower surfaces

2a, 2a of the processed piezoelectric ceramic body 2, and an electrode layer is formed by baking to produce a piezoelectric member 1 as a sample. The electromechanical coupling coefficient Kp in the radial vibration of the disk-shaped piezoelectric ceramic body 2 forming each sample was determined in accordance with the Japan Electronics Industry Association Standard EMA-6100.
[0031]
Further, by firing under the same composition and the same conditions as the above-described sample, a piezoelectric ceramic body 2 having a fired dimension of φ15 mm × 0.5 mm is manufactured, and silver is formed on the upper and lower surfaces of the piezoelectric ceramic body 2. An electrode layer made of glass and a glass component is formed by baking, and a sample subjected to polarization treatment under the same conditions is prepared as a reference sample, and the radial direction of the disk-shaped piezoelectric ceramic body 2 forming the reference sample is prepared. The electromechanical coupling coefficient Kp in vibration is performed in accordance with the Japan Electronics Industry Association standard EMAS-6100, and the ratio of the electromechanical coupling coefficient Kp of each sample to the electromechanical coupling coefficient Kp of the reference sample The measurement was made as the rate of decrease of the coefficient Kp, and the rate of decrease of less than 5% was evaluated as excellent.
[0032]
The results are as shown in Table 1.
[0033]
[Table 1]

[0034]
As a result, as shown in Table 1, sample No. 16-19, 22-25, 28-31, and 34-37 have a surface roughness on each surface of the piezoelectric ceramic body 2 of 0.3 μm or less in arithmetic mean roughness (Ra) and a maximum height (Ry ) And the processed surface is a surface perpendicular to the polarization direction (upper and

lower surfaces

2a, 2a of the piezoelectric ceramic body), the tetragonal crystal when the processed surface is measured by X-ray diffraction The ratio (A / B) between the peak intensity A of 200 diffraction and the peak intensity B of tetragonal 002 diffraction is 1.5 or less, and the processed surface is parallel to the polarization direction (side surface of the piezoelectric ceramic body 2). 2b), the ratio (B / A) between the peak intensity B of tetragonal 002 diffraction and the peak intensity A of tetragonal 200 diffraction when the processed surface is measured by X-ray diffraction is 1.5 or less. Because there is a big Kokizu and microcracks little, it is possible to suppress the decrease rate of the electro-mechanical coupling coefficient Kp before and after machining to less than 5%, it was excellent.
[0035]
In particular, sample no . As in 29-31 and 35-37, the ratio of the peak intensity on each processed surface is set to 1.0 or less, so that the rate of decrease of the electromechanical coupling coefficient Kp before and after processing can be suppressed to less than 2%. In addition, sample no. As in 35 to 37, by setting the ratio of the peak intensity on each processed surface to 0.9 or less, the reduction rate of the electromechanical coupling coefficient Kp before and after processing can be made less than 1%, and the piezoelectric ceramic body 2 It can be seen that the original electromechanical coupling coefficient of can be obtained.
[0036]
【The invention's effect】
As described above, according to the present invention, all of the surface, a piezoelectric ceramic body at least one of which is a decorated with by processing the surface of the polishing and grinding, respectively on opposite surfaces of at least a pair In the piezoelectric member provided with electrodes and subjected to polarization treatment between the electrodes, the processed surface is composed of a surface perpendicular to the polarization direction and a surface parallel to the polarization direction, and is a surface perpendicular to the polarization direction. For a certain processed surface, the ratio (A / B) between the peak intensity A of tetragonal 200 diffraction and the peak intensity B of tetragonal 002 diffraction when the processed surface is measured by X-ray diffraction is 1.5 or less. the ratio between, and in the working surface is a surface parallel to a separatory pole direction, a tetragonal 002 diffraction peak intensity B and the peak intensity a tetragonal 200 diffraction when measuring the working surface by X-ray diffraction (B / A) By making the following, it prevents the piezoelectric characteristics such as electromechanical coupling coefficient inherent to the piezoelectric ceramic body from being degraded by processing such as grinding and polishing, and improves the conversion efficiency between electrical energy and mechanical energy Can be made.
[0037]
Therefore, if the piezoelectric member of the present invention is used for a piezoelectric actuator used in a piezoelectric buzzer, an ink jet recording head, an ultrasonic motor or the like, a large amount of displacement can be obtained, and if used in a piezoelectric sensor or an acceleration sensor, Even small changes can be detected with high sensitivity, and further, if used for an oscillator or a resonator, a product having a constant resonance frequency characteristic can be obtained stably.
[Brief description of the drawings]
1A and 1B are diagrams showing an example of a piezoelectric member according to the present invention, in which FIG. 1A is a perspective view with a part broken away, and FIG.
[Explanation of symbols]
1: Piezoelectric member 2: Piezoelectric ceramic body 2a: Upper and lower surfaces 2b of the piezoelectric ceramic body: Side surfaces of the piezoelectric ceramic body 3: Electrodes

Claims

All surfaces, a piezoelectric ceramic body at least one of which is a decorated with by processing the surface of the polishing and grinding, with each electrode on the opposing surface of at least a pair, a polarization treatment between the electrodes In the applied piezoelectric member, the processed surface is composed of a surface perpendicular to the polarization direction and a surface parallel to the polarization direction, and the processed surface is a surface perpendicular to the polarization direction. the ratio of the peak intensity B of the peak intensity a tetragonal 200 diffraction when measured by X-ray diffraction tetragonal 002 diffraction (a / B) is 1.5 or less, in the surface parallel to the partial pole direction In a certain processed surface, the ratio (B / A) of the peak intensity B of tetragonal 002 diffraction and the peak intensity A of tetragonal 200 diffraction when the processed surface is measured by X-ray diffraction is 1.5 or less. It is characterized by Collecting member.