JP3781317B2 - Piezoelectric ceramic material - Google Patents
Piezoelectric ceramic material Download PDFInfo
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- JP3781317B2 JP3781317B2 JP15542796A JP15542796A JP3781317B2 JP 3781317 B2 JP3781317 B2 JP 3781317B2 JP 15542796 A JP15542796 A JP 15542796A JP 15542796 A JP15542796 A JP 15542796A JP 3781317 B2 JP3781317 B2 JP 3781317B2
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- 229910010293 ceramic material Inorganic materials 0.000 title claims description 19
- 239000000203 mixture Substances 0.000 claims description 24
- 238000005245 sintering Methods 0.000 description 21
- 239000000919 ceramic Substances 0.000 description 11
- 238000004519 manufacturing process Methods 0.000 description 9
- 230000008020 evaporation Effects 0.000 description 7
- 238000001704 evaporation Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 239000002131 composite material Substances 0.000 description 5
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 101100513612 Microdochium nivale MnCO gene Proteins 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 229910010413 TiO 2 Inorganic materials 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000005621 ferroelectricity Effects 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
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Description
【0001】
【発明の属する利用分野】
本発明は、例えば各種超音波振動子,セラミックフィルタ,圧電発音体,圧電アクチュエーター等の圧電磁器製造物に利用される圧電磁器材料に関する。
【0002】
【従来の技術】
近年、圧電磁器材料としてはPbTiO3 やPbZrO3 を主成分として含む圧電セラミック(以下、PZT系圧電セラミックと略する)が汎用的に用いられている。一般に、この種の圧電セラミックでは、その製造に要する焼結温度が二成分系では約1260℃であり、更に特性改善のために複合ペロブスカイト類を第三成分,第四成分として固溶させた多成分PZT系圧電セラミックでは、焼結温度が多少低下して1200℃近辺となっている。
【0003】
ところで、PZT系圧電セラミックの焼結過程において、主成分の一つであるPbOの蒸発が1000℃近辺から急激に増加することが知られている。従って、上記の温度領域では多量のPbO蒸発が起こるという問題がある。PbOが蒸発すると、焼結体の組成ずれを引き起こし、特性のばらつきや劣化を招く上、蒸発したPb成分は環境汚染の原因となる。
【0004】
そこで、PbOの蒸発を制御することはPZT系圧電セラミックの製造上、非常に重要となっており、このためには焼結温度を1000℃以下にすることが望ましい。焼結温度の低下は省エネルギーの点でも有益である上に、例えば一体焼成で製造される積層型圧電素子の場合、焼結温度が低下できれば内部電極の構成においてパラジウムを減らし、銀の比率を増大させることが可能であり、製造コスト面で有利となると期待される。このように、圧電磁器材料の焼結温度を低下させることは製造コスト面で長所を奏する他、省エネルギーを具現化する点でも有益である。
【0005】
【発明が解決しようとする課題】
上述したPZT系圧電セラミックの場合、一般に焼結温度が通常1200℃以上であるため、PbOの蒸発を回避したり、或いは製造コストを低減化させることが困難となっている。
【0006】
本発明は、このような問題点を解決すべくなされたもので、その技術的課題は、PbOの蒸発を回避できる低温(1000℃以下)で焼成可能であると共に、製造コストを低減化し得る圧電磁器材料を提供することにある。
【0007】
【課題を解決するための手段】
本発明によれば、組成式aPbTiO3 +bPbZrO3 +cPb(Mn1/3 Sb2/3 )O3 +dPb(Zn1/3 Nb2/3 )O3 +eZnO+fPbOで表わされると共に、a=10〜60[mol%],b=10〜65[mol%],c=3〜20[mol%],d=0〜65[mol%](但し、a+b+c+d=100)とする主成分と、該主成分重量(主成分を重量で100%としたとき)に対してe=0.2〜2.5[wt%],f=0〜8[wt%]として添加された副成分とを含む圧電磁器材料が得られる。
【0008】
又、本発明によれば、組成式aPbTiO3 +bPbZrO3 +cPb(Mn1/3 Nb2/3 )O3 +dPb(Zn1/3 Nb2/3 )O3 +eZnO+fPbOで表わされると共に、a=10〜55[mol%],b=10〜60[mol%],c=2〜40[mol%],d=0〜65[mol%](但し、a+b+c+d=100)とする主成分と、該主成分重量に対してe=0.2〜2.5[wt%],f=0〜8[wt%]として添加された副成分とを含む圧電磁器材料が得られる。
【0009】
【発明の実施の形態】
以下に実施例を挙げ、本発明の圧電磁器材料について、図面を参照して詳細に説明する。
【0010】
最初に、本発明の圧電磁器材料の概要並びにその具現に至る背景を簡単に説明する。この圧電磁器材料の一例は、組成式aPbTiO3 +bPbZrO3 +cPb(Mn1/3 Sb2/3 )O3 +dPb(Zn1/3 Nb2/3 )O3 +eZnO+fPbOで表わされ、更に、a=10〜60[mol%],b=10〜65[mol%],c=3〜20[mol%],d=0〜65[mol%](但し、a+b+c+d=100)とする主成分と、この主成分重量(主成分を重量で100%としたとき)に対してe=0.2〜2.5[wt%],f=0〜8[wt%]として添加された副成分とを含むものである。
【0011】
又、この圧電磁器材料の他例は、組成式aPbTiO3 +bPbZrO3 +cPb(Mn1/3 Nb2/3 )O3 +dPb(Zn1/3 Nb2/3 )O3 +eZnO+fPbOで表わされると共に、a=10〜55[mol%],b=10〜60[mol%],c=2〜40[mol%],d=0〜65[mol%](但し、a+b+c+d=100)とする主成分と、該主成分重量に対してe=0.2〜2.5[wt%],f=0〜8[wt%]として添加された副成分とを含むものである。このような組成によりPbOの蒸発を回避可能な低温(1000℃以下)で焼成可能となる。
【0012】
一般に、PbTiO3 及びPbZrO3 の固溶体に、AサイトにPbを有する複合ペロブスカイト類を第三成分として固溶させる場合、この比率が多いほど一般には焼結温度が低下する。これは複合ペロブスカイト類の融点が低い(1200℃未満)ことに起因している。ところが、これらの含有率が高くなるに従って強誘電性を有する組成範囲ではキュリー温度が低下する。
【0013】
多成分のPZT系圧電セラミックは、複合ペロブスカイト類を一種若しくは複数種としてPbTiO3 −PbZrO3 に固溶させることにより、二成分系では得られなかった誘電的,圧電的な特性改善がなされて実用に供される。又、PbTiO3 −PbZrO3 −Pb(Mn1/3 E2/3 )O3 (但し、E=Sb,Nb)系圧電セラミックは、Pb(Mn1/3 Sb2/3 )O3 又はPb(Mn1/3 Nb2/3 )O3 を固溶させることで数百〜数千の機械的品質係数と高い誘電的,圧電的な特性とが得られるが、実用的な組成範囲はPb(Mn1/3 Sb2/3 )O3 の比率が20mol%以下、又Pb(Mn1/3 Nb2/3 )O3 の比率が40mol%以下である。これはこの値を越えるとキュリー温度が200℃以下となり、誘電的,圧電的な特性における温度安定性が低下するためである。
【0014】
本発明では、PbTiO3 −PbZrO3 −Pb(Mn1/3 E2/3 )O3 (但し、E=Sb,Nb)系に、更に第四の複合ペロブスカイト類として、強誘電性でキュリー温度が比較的高いPb(Zn1/3 Nb2/3 )O3 を選んで固溶させることで、キュリー温度の低下を抑え、比較的機械的品質係数が高く、しかも1000℃以下の低温で焼結できる組成を見い出している。
【0015】
しかしながら、PbTiO3 −PbZrO3 −Pb(Mn1/3 E2/3 )O3 −Pb(Zn1/3 Nb2/3 )O3 (但し、E=Sb,Nb)の組成のみでは焼結体に巨大ボイドが生じ易く、実用面で問題がある。
【0016】
そこで、一定量のZnOを添加することで、巨大ボイドの発生が著しく抑制されると共に、焼結性が改善されて実用的な誘電圧電特性を有する組成となることが判明した。又、ZnOはPb(Zn1/3 Nb2/3 )O3 が存在しない条件下でも単独で焼結温度の低下を可能にすることが明らかとなった。更に、ZnOに加えてPbOを添加すると、焼結温度を一層低下させ得ることが確認された。
【0017】
以下は、本発明の圧電磁器材料をその製造工程を含めて具体的な幾つかの実施例(比較例を含む)に基づいて説明する。
【0018】
[実施例1]
実施例1では、最初に主成分及び副成分の原料として、PbO,TiO2 ,ZrO2 ,MnCO3 ,Sb2 O3 ,Nb2 O5 ,及びZnOをそれぞれ異なる組成となるように秤量し、これらの原料粉をジルコニアボールと一緒にアクリルポット中に入れて20時間湿式混合した。
【0019】
次に、これらの混合粉を脱水乾燥後、アルミナこう鉢中で温度800℃の条件下で2時間予焼を行ってから各予焼粉をアクリルポット中ジルコニアボールにて15時間湿式粉砕した。
【0020】
引き続き、蒸発乾燥して得られた各予焼粉砕にバインダを混合して加圧し、直径φが15mm,厚さ3mmとなるように成形した。これらの成形体を750〜1050[℃]で2時間焼成し、各焼結体を1mmの厚さに加工した後、両面に銀ペーストを塗布して温度条件450℃で焼き付けて電極を形成することにより、それぞれ組成の異なる総計28種の試料とした。
【0021】
このようにして得られた各試料を100℃,4kV/mmの条件下で15分間に及ぶ分極処理を施した後、比誘電率εr ,電気機械結合係数Kp ,機械的品質係数Qm を測定したところ、表1に示すような結果(各試料の組成を含む)となった。
【0022】
【表1】
【0023】
因みに、表1においてTc はキュリー温度であり、T.S.は焼結体密度ρが7.5g/cm3 以上となるのに必要な最低の焼結温度である。尚、図1は表1における各試料のうちの代表的な例(試料No.19,No.20,No.26,No.27のもの)に関する焼結温度に対する焼結体密度の関係を示したものである。
【0024】
表1からは、本発明の圧電磁器材料に関して組成範囲を決定する理由として、排除されるべき以下の第1乃至第6の不適当事項を列挙することができる。即ち、各試料のうち、εr <400(試料No.12,No.14),Kp <25(試料No.4,No.6,No.8,No.12,No.14),Qm <500(試料No.1,No.8,No.10),Tc <200℃(試料No.4,No.6,No.8)のものに関しては実用性に乏しいため、本発明の実施例から除外される。
【0025】
第1の不適当事項は、試料No.8のようにPbTiO3 量aが10mol%未満ではKp ,Qm ,Tc が低い値となって好ましくないこと、更に試料No.12のように60mol%を越えてもεr ,Kp が低い値となって好ましくないことである。
【0026】
第2の不適当事項は、試料No.10のようにPbZrO3 量bが10mol%未満ではQm が低下して好ましくないこと、更に試料No.14のように65mol%を越えてもεr ,Kp が低い値となって好ましくないことである。
【0027】
第3の不適当事項は、試料No.1のようにPb(Mn1/3 Sb2/3 )O3 量cが3mol%未満ではQm が低下して好ましくないこと、更に試料No.4のように20mol%を越えてもKp ,Tc が低い値となって好ましくないことである。
【0028】
第4の不適当事項は、試料No.6のようにPb(Zn1/3 Nb2/3 )O3 量dが65mol%を越えるとKp ,Tc が低い値となって好ましくないことである。
【0029】
第5の不適当事項は、試料No.15,No.22のようにZnO量eが主成分全重量に対して0.2wt%未満では焼結体に巨大ボイドが生じて組織が不均質となるため好ましくないこと、更に試料No.18,No.25のように2.5wt%を越えても組織が不均質となって好ましくないことである。
【0030】
第6の不適当事項は、試料No.21,No.28のようにPbO量fが8wt%を越えると巨大ボイドが生じて好ましくないことである。
【0031】
このような各不適当事項に該当する試料と特性が劣化した試料とを排除することにより、組成式aPbTiO3 +bPbZrO3 +cPb(Mn1/3 Sb2/3 )O3 +dPb(Zn1/3 Nb2/3 )O3 +eZnO+fPbOにおいて、aを10〜60[mol%],bを10〜65[mol%],cを3〜20[mol%],dを0〜65[mol%](但し、a+b+c+d=100とする)から成る主成分に関し、その主成分重量に対してeを0.2〜2.5[wt%],fを0〜8[wt%]とする副成分を添加するという組成の決定ができ、高特性で1000℃以下の低温で焼成可能な圧電磁器材料が得られる。
【0032】
即ち、表1に示した総計28種の試料のうち、試料No.2,No.3,No.5,No.7,No.9,No.11,No.13,No.16,No.17,No.19,No.20,No.23,No.24,No.26,No.27のものは、本発明の実施例となり、これ以外の試料No.1,No.4,No.6,No.8,No.10,No.12,No.14,No.15,No.18,No.21,No.22,No.25,No.28のものは本発明外の比較例となっている。
【0033】
尚、図1に示した各試料(試料No.19,No.20,No.26,No.27)関して、表1中の試料No.19のものからはPb(Zn1/3 Nb2/3 )O3 が存在しない条件でもZnOが単独で焼結温度の低下に効果を示すことが判り、しかも表1中の試料No.19,No.20,No.26,No.27のものからは更にPbOを添加することによって焼結温度を一層低下させ得ることが判る。
【0034】
[実施例2]
実施例2では、最初に主成分及び副成分の原料として、PbO,TiO2 ,ZrO2 ,MnCO3 ,Nb2 O5 ,及びZnOをそれぞれ異なる組成となるように秤量し、これらの原料粉を用いて実施例1の場合と同じ条件でそれぞれ組成の異なる総計30種の試料とした。
【0035】
このようにして得られた各試料を100℃,4kV/mmの条件下で15分間に及ぶ分極処理を施した後、比誘電率εr ,電気機械結合係数Kp ,機械的品質係数Qm を測定したところ、表2に示すような結果(各試料の組成を含む)となった。
【0036】
【表2】
【0037】
因みに、表2においてTc はキュリー温度であり、T.S.は焼結体密度ρが7.5g/cm3 以上となるのに必要な最低の焼結温度である。尚、図2は表2における各試料のうちの代表的な例(試料No.19,No.20,No.26,No.27のもの)に関する焼結温度に対する焼結体密度の関係を示したものである。
【0038】
ここでも、表2からは、本発明の圧電磁器材料に関して組成範囲を決定する理由として、排除されるべき以下の第1乃至第6の不適当事項を列挙することができる。即ち、各試料のうち、εr <400(試料No.8,No.12,No.14),Kp <25(試料No.4,No.6,No.8,No.12,No.14),Qm <500(試料No.1,No.8,No.10),Tc <200℃(試料No.4,No.6,No.8)のものに関しては実用性に乏しいため、本発明の実施例から除外される。
【0039】
第1の不適当事項は、試料No.8のようにPbTiO3 量aが10mol%未満ではεr ,Kp ,Qm ,Tc が低い値となって好ましくないこと、更に試料No.12のように55mol%を超過してもεr ,Kp が低い値となって好ましくないことである。
【0040】
第2の不適当事項は、試料No.10のようにPbZrO3 量bが10mol%未満ではQm が低下して好ましくないこと、更に試料No.14のように60mol%を越えてもεr ,Kp が低い値となって好ましくないことである。
【0041】
第3の不適当事項は、試料No.1のようにPb(Mn1/3 Nb2/3 )O3 量cが2mol%未満ではQm が低下して好ましくないこと、更に試料No.4のように40mol%を越えてもKp ,Tc が低い値となって好ましくないことである。
【0042】
第4の不適当事項は、試料No.6のようにPb(Zn1/3 Nb2/3 )O3 量dが65mol%を越えるとKp ,Tc が低い値となって好ましくないことである。
【0043】
第5の不適当事項は、試料No.15,No.22のようにZnO量eが主成分全重量に対して0.2wt%未満では焼結体に巨大ボイドが生じて組織が不均質となるため好ましくないこと、更に試料No.18,No.25のように2.5wt%を越えても組織が不均質となって好ましくないことである。
【0044】
第6の不適当事項は、試料No.21,No.28のようにPbO量fが8wt%を越えると巨大ボイドが生じて好ましくないことである。
【0045】
このような各不適当事項に該当する試料と特性が劣化した試料とを排除することにより、組成式aPbTiO3 +bPbZrO3 +cPb(Mn1/3 Nb2/3 )O3 +dPb(Zn1/3 Nb2/3 )O3 +eZnO+fPbOにおいて、aを10〜55[mol%],bを10〜65[mol%],cを2〜40[mol%],dを0〜65[mol%](但し、a+b+c+d=100とする)から成る主成分に関し、その主成分重量に対してeを0.2〜2.5[wt%],fを0〜8[wt%]とする副成分を添加するという組成の決定ができ、高特性で1000℃以下の低温で焼成可能な圧電磁器材料が得られる。
【0046】
即ち、表2に示した総計30種の試料のうち、試料No.2,No.3,No.5,No.7,No.9,No.11,No.13,No.16,No.17,No.19,No.20,No.23,No.24,No.26,No.27,No.29,No.30のものは、本発明の実施例となり、これ以外の試料No.1,No.4,No.6,No.8,No.10,No.12,No.14,No.15,No.18,No.21,No.22,No.25,No.28のものは本発明外の比較例となっている。
【0047】
尚、図2に示した各試料(試料No.19,No.20,No.26,No.27)関して、表2中の試料No.19のものからはPb(Zn1/3 Nb2/3 )O3 が存在しない条件でもZnOが単独で焼結温度の低下に効果を示すことが判り、しかも表2中の試料No.19,No.20,No.26,No.27のものからは更にPbOを添加することによって焼結温度を一層低下させ得ることが判る。又、試料No.29,No.30のものの組成では、特性的に極めて優れた材料が得られることが判る。
【0048】
【発明の効果】
以上に述べた通り、本発明によれば、主成分及び副成分としてのPbTiO3 ,PbZrO3 ,Pb(Mn1/3 E2/3 )O3 (但し、E=Sb,Nb),Pb(Zn1/3 Nb2/3 )O3 ,ZnO,PbOを適量範囲で用いることにより、PbOの蒸発を回避できる1000℃以下の低温で焼成可能で、しかも比誘電率εr が400以上,電気機械結合係数Kp が25以上,機械的品質係数Qm が500以上,キュリー温度Tc が200℃以上の優れた特性を有する圧電体材料を省エネルギーで低コストで製造可能となるため、工業的に有益となる。
【図面の簡単な説明】
【図1】本発明の圧電磁器材料の製造工程を説明した実施例1において作製した各試料のうちの代表的なものに関する焼結温度に対する焼結体密度の関係を示したものである。
【図2】本発明の圧電磁器材料の製造工程を説明した実施例2において作製した各試料のうちの代表的なものに関する焼結温度に対する焼結体密度の関係を示したものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric ceramic material used for piezoelectric ceramic products such as various ultrasonic vibrators, ceramic filters, piezoelectric sounding bodies, piezoelectric actuators and the like.
[0002]
[Prior art]
In recent years, piezoelectric ceramics containing PbTiO 3 and PbZrO 3 as main components (hereinafter abbreviated as PZT piezoelectric ceramics) have been widely used as piezoelectric ceramic materials. In general, in this type of piezoelectric ceramic, the sintering temperature required for its production is about 1260 ° C. in a two-component system, and a composite perovskite is dissolved as a third component and a fourth component to further improve the characteristics. In the component PZT-based piezoelectric ceramic, the sintering temperature is somewhat lowered to around 1200 ° C.
[0003]
Incidentally, it is known that the evaporation of PbO, which is one of the main components, rapidly increases from around 1000 ° C. during the sintering process of the PZT-based piezoelectric ceramic. Therefore, there is a problem that a large amount of PbO is evaporated in the above temperature range. When PbO evaporates, the composition of the sintered body is shifted, resulting in characteristic variations and deterioration, and the evaporated Pb component causes environmental pollution.
[0004]
Therefore, controlling the evaporation of PbO is very important for the production of PZT piezoelectric ceramics. For this purpose, it is desirable to set the sintering temperature to 1000 ° C. or lower. Lowering the sintering temperature is beneficial in terms of energy saving. For example, in the case of a laminated piezoelectric element manufactured by integral firing, if the sintering temperature can be reduced, the internal electrode structure reduces palladium and increases the silver ratio. This is expected to be advantageous in terms of manufacturing cost. Thus, lowering the sintering temperature of the piezoelectric ceramic material has advantages in terms of manufacturing cost and is also advantageous in realizing energy saving.
[0005]
[Problems to be solved by the invention]
In the case of the above-described PZT-based piezoelectric ceramic, since the sintering temperature is generally 1200 ° C. or higher, it is difficult to avoid evaporation of PbO or reduce the manufacturing cost.
[0006]
The present invention has been made to solve such problems, and its technical problem is that a piezoelectric material that can be fired at a low temperature (1000 ° C. or less) that can avoid evaporation of PbO and that can reduce the manufacturing cost. It is to provide a porcelain material.
[0007]
[Means for Solving the Problems]
According to the present invention, the composition formula is represented by aPbTiO 3 + bPbZrO 3 + cPb (Mn 1/3 Sb 2/3 ) O 3 + dPb (Zn 1/3 Nb 2/3 ) O 3 + eZnO + fPbO, and a = 10 to 60 [ mol%], b = 10 to 65 [mol%], c = 3 to 20 [mol%], d = 0 to 65 [mol%] (where a + b + c + d = 100), and the weight of the principal component Piezoelectric ceramic material including subcomponents added as e = 0.2-2.5 [wt%] and f = 0-8 [wt%] with respect to (when the main component is 100% by weight) Is obtained.
[0008]
According to the present invention, the composition formula is represented by aPbTiO 3 + bPbZrO 3 + cPb (Mn 1/3 Nb 2/3 ) O 3 + dPb (Zn 1/3 Nb 2/3 ) O 3 + eZnO + fPbO, and a = 10 55 [mol%], b = 10-60 [mol%], c = 2-40 [mol%], d = 0-65 [mol%] (provided that a + b + c + d = 100) A piezoelectric ceramic material including subcomponents added as e = 0.2-2.5 [wt%] and f = 0-8 [wt%] with respect to the component weight is obtained.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Examples will be given below, and the piezoelectric ceramic material of the present invention will be described in detail with reference to the drawings.
[0010]
First, the outline of the piezoelectric ceramic material of the present invention and the background leading to its implementation will be briefly described. An example of this piezoelectric ceramic material is represented by the composition formula aPbTiO 3 + bPbZrO 3 + cPb (Mn 1/3 Sb 2/3 ) O 3 + dPb (Zn 1/3 Nb 2/3 ) O 3 + eZnO + fPbO, and a = 10-60 [mol%], b = 10-65 [mol%], c = 3-20 [mol%], d = 0-65 [mol%] (however, a + b + c + d = 100) Subcomponents added as e = 0.2 to 2.5 [wt%] and f = 0 to 8 [wt%] with respect to the main component weight (when the main component is 100% by weight) Is included.
[0011]
Another example of this piezoelectric ceramic material is represented by the composition formula aPbTiO 3 + bPbZrO 3 + cPb (Mn 1/3 Nb 2/3 ) O 3 + dPb (Zn 1/3 Nb 2/3 ) O 3 + eZnO + fPbO, and a = 10 to 55 [mol%], b = 10 to 60 [mol%], c = 2 to 40 [mol%], d = 0 to 65 [mol%] (however, a + b + c + d = 100) And subcomponents added as e = 0.2-2.5 [wt%] and f = 0-8 [wt%] with respect to the main component weight. With such a composition, firing can be performed at a low temperature (1000 ° C. or lower) at which PbO evaporation can be avoided.
[0012]
In general, when a composite perovskite having Pb at the A site is dissolved as a third component in a solid solution of PbTiO 3 and PbZrO 3 , the sintering temperature generally decreases as the ratio increases. This is due to the low melting point of composite perovskites (less than 1200 ° C.). However, the Curie temperature decreases in the composition range having ferroelectricity as the content thereof increases.
[0013]
Multi-component PZT-based piezoelectric ceramics can be used practically by improving the dielectric and piezoelectric properties that could not be obtained with two-component systems by dissolving single or multiple composite perovskites in PbTiO 3 -PbZrO 3. To be served. PbTiO 3 —PbZrO 3 —Pb (Mn 1/3 E 2/3 ) O 3 (where E = Sb, Nb) based piezoelectric ceramic is Pb (Mn 1/3 Sb 2/3 ) O 3 or Pb By dissolving (Mn 1/3 Nb 2/3 ) O 3 , several hundred to several thousand mechanical quality factors and high dielectric and piezoelectric characteristics can be obtained, but the practical composition range is Pb. The ratio of (Mn 1/3 Sb 2/3 ) O 3 is 20 mol% or less, and the ratio of Pb (Mn 1/3 Nb 2/3 ) O 3 is 40 mol% or less. This is because when this value is exceeded, the Curie temperature becomes 200 ° C. or lower, and the temperature stability in the dielectric and piezoelectric characteristics decreases.
[0014]
In the present invention, the PbTiO 3 —PbZrO 3 —Pb (Mn 1/3 E 2/3 ) O 3 (where E = Sb, Nb) system is further used as a fourth composite perovskite, which is ferroelectric and has a Curie temperature. By selecting Pb (Zn 1/3 Nb 2/3 ) O 3 with a relatively high solid solution, the decrease in Curie temperature is suppressed, the mechanical quality factor is relatively high, and the firing is performed at a low temperature of 1000 ° C. or lower. The composition which can conclude is found.
[0015]
However, only the composition of PbTiO 3 —PbZrO 3 —Pb (Mn 1/3 E 2/3 ) O 3 —Pb (Zn 1/3 Nb 2/3 ) O 3 (where E = Sb, Nb) is sintered. Large voids are easily generated in the body, which is problematic in practical use.
[0016]
Thus, it has been found that the addition of a certain amount of ZnO significantly suppresses the generation of giant voids, improves the sinterability, and provides a composition having practical dielectric piezoelectric characteristics. It has also been clarified that ZnO alone can lower the sintering temperature even in the absence of Pb (Zn 1/3 Nb 2/3 ) O 3 . Furthermore, it was confirmed that the sintering temperature can be further reduced by adding PbO in addition to ZnO.
[0017]
In the following, the piezoelectric ceramic material of the present invention will be described based on some specific examples (including comparative examples) including the manufacturing process.
[0018]
[Example 1]
In Example 1, first, PbO, TiO 2 , ZrO 2 , MnCO 3 , Sb 2 O 3 , Nb 2 O 5 , and ZnO are weighed so as to have different compositions as raw materials for the main component and the subcomponent, These raw material powders were placed in an acrylic pot together with zirconia balls and wet mixed for 20 hours.
[0019]
Next, these mixed powders were dehydrated and dried, and then pre-fired in an alumina pot for 2 hours at a temperature of 800 ° C., and then each pre-fired powder was wet-ground with zirconia balls in an acrylic pot for 15 hours.
[0020]
Subsequently, each pre-fired pulverized product obtained by evaporation drying was mixed with a binder and pressed to form a diameter φ of 15 mm and a thickness of 3 mm. After firing these molded bodies at 750 to 1050 [° C.] for 2 hours and processing each sintered body to a thickness of 1 mm, a silver paste is applied to both surfaces and baked at a temperature condition of 450 ° C. to form electrodes. Thus, a total of 28 samples having different compositions were obtained.
[0021]
Each sample thus obtained was subjected to a polarization treatment for 15 minutes under the conditions of 100 ° C. and 4 kV / mm, and then the relative permittivity ε r , electromechanical coupling coefficient K p , mechanical quality factor Q m Was measured and the results shown in Table 1 (including the composition of each sample) were obtained.
[0022]
[Table 1]
[0023]
In Table 1, T c is the Curie temperature. S. Is the minimum sintering temperature necessary for the sintered body density ρ to be 7.5 g / cm 3 or more. 1 shows the relationship of the sintered body density to the sintering temperature for representative examples (samples No. 19, No. 20, No. 26, No. 27) of each sample in Table 1. It is a thing.
[0024]
From Table 1, the following first to sixth inappropriate matters to be excluded can be listed as reasons for determining the composition range for the piezoelectric ceramic material of the present invention. That is, among each sample, ε r <400 (sample No. 12, No. 14), K p <25 (sample No. 4, No. 6, No. 8, No. 12, No. 14), Q Since m <500 (sample No. 1, No. 8, No. 10), T c <200 ° C. (sample No. 4, No. 6, No. 8), it is poor in practicality. Excluded from the examples.
[0025]
The first inadequate matter is sample no. PbTiO 3 amount a is K p is less than 10 mol% as 8, Q m, T c is undesirable becomes low, further Sample No. Even if it exceeds 60 mol% as shown in FIG. 12, ε r and K p are not preferable because of low values.
[0026]
The second inadequate matter is sample no. It PbZrO 3 amount b as 10 undesirably reduces the Q m is less than 10 mol%, further Sample No. Even if it exceeds 65 mol% as shown in FIG. 14, ε r and K p are not preferable because of low values.
[0027]
The third inadequate matter is sample no. 1 as Pb (Mn 1/3 Sb 2/3) that O 3 amount c is not preferable to decrease Q m is less than 3 mol%, further Sample No. Even if it exceeds 20 mol% as shown in 4, K p and T c become low values, which is not preferable.
[0028]
The fourth inadequate matter is sample no. As shown in FIG. 6, when the amount d of Pb (Zn 1/3 Nb 2/3 ) O 3 exceeds 65 mol%, K p and T c become low values, which is not preferable.
[0029]
The fifth inadequate matter is sample no. 15, no. When the ZnO amount e is less than 0.2 wt% with respect to the total weight of the main component as in No. 22, it is not preferable because giant voids are formed in the sintered body and the structure becomes inhomogeneous. 18, no. Even if it exceeds 2.5 wt% as in 25, the structure becomes inhomogeneous, which is not preferable.
[0030]
The sixth inappropriate matter is that of sample No. 21, no. When the PbO amount f exceeds 8 wt% as in No. 28, a huge void is generated, which is not preferable.
[0031]
By eliminating the sample corresponding to each of these inappropriate matters and the sample having deteriorated characteristics, the composition formula aPbTiO 3 + bPbZrO 3 + cPb (Mn 1/3 Sb 2/3 ) O 3 + dPb (Zn 1/3 Nb 2/3 ) In O 3 + eZnO + fPbO, a is 10 to 60 [mol%], b is 10 to 65 [mol%], c is 3 to 20 [mol%], and d is 0 to 65 [mol%] (however, , A + b + c + d = 100) is added, and subcomponents with e being 0.2 to 2.5 [wt%] and f being 0 to 8 [wt%] based on the weight of the principal component are added. Thus, a piezoelectric ceramic material having high characteristics and capable of being fired at a low temperature of 1000 ° C. or lower can be obtained.
[0032]
That is, among the total of 28 types of samples shown in Table 1, sample No. 2, no. 3, No. 5, no. 7, no. 9, no. 11, no. 13, no. 16, no. 17, no. 19, no. 20, no. 23, no. 24, no. 26, no. No. 27 is an example of the present invention. 1, No. 1 4, no. 6, no. 8, no. 10, no. 12, no. 14, no. 15, no. 18, no. 21, no. 22, no. 25, no. 28 is a comparative example outside the present invention.
[0033]
In addition, regarding each sample (sample No. 19, No. 20, No. 26, No. 27) shown in FIG. No. 19 shows that ZnO alone has an effect on lowering the sintering temperature even in the absence of Pb (Zn 1/3 Nb 2/3 ) O 3 . 19, no. 20, no. 26, no. 27 shows that the sintering temperature can be further reduced by adding PbO.
[0034]
[Example 2]
In Example 2, first, PbO, TiO 2 , ZrO 2 , MnCO 3 , Nb 2 O 5 , and ZnO are weighed so as to have different compositions as raw materials of the main component and the subcomponent, and these raw material powders are measured. A total of 30 samples having different compositions were used under the same conditions as in Example 1.
[0035]
Each sample thus obtained was subjected to a polarization treatment for 15 minutes under the conditions of 100 ° C. and 4 kV / mm, and then the relative permittivity ε r , electromechanical coupling coefficient K p , mechanical quality factor Q m Was measured and the results shown in Table 2 (including the composition of each sample) were obtained.
[0036]
[Table 2]
[0037]
In Table 2, T c is the Curie temperature. S. Is the minimum sintering temperature necessary for the sintered body density ρ to be 7.5 g / cm 3 or more. 2 shows the relationship of the sintered body density to the sintering temperature for representative examples (sample No. 19, No. 20, No. 26, No. 27) of each sample in Table 2. It is a thing.
[0038]
Here again, from Table 2, the following first to sixth inappropriate matters to be excluded can be listed as reasons for determining the composition range for the piezoelectric ceramic material of the present invention. That is, among the samples, ε r <400 (sample No. 8, No. 12, No. 14), K p <25 (sample No. 4, No. 6, No. 8, No. 12, No. 12). 14), Q m <500 (sample No. 1, No. 8, No. 10), T c <200 ° C. (sample No. 4, No. 6, No. 8), because of lack of practicality Are excluded from the embodiments of the present invention.
[0039]
The first inadequate matter is sample no. As shown in FIG. 8, when the PbTiO 3 amount a is less than 10 mol%, ε r , K p , Q m , and T c are low, which is not preferable. Even if it exceeds 55 mol% as shown in FIG. 12, ε r and K p are not preferable because of low values.
[0040]
The second inadequate matter is sample no. It PbZrO 3 amount b as 10 undesirably reduces the Q m is less than 10 mol%, further Sample No. Even if it exceeds 60 mol% as shown in FIG. 14, ε r and K p are low and are not preferable.
[0041]
The third inadequate matter is sample no. As shown in FIG. 1, when the amount c of Pb (Mn 1/3 Nb 2/3 ) O 3 is less than 2 mol%, Q m decreases, which is not preferable. Even if it exceeds 40 mol% as shown in 4, K p and T c become low values, which is not preferable.
[0042]
The fourth inadequate matter is sample no. As shown in FIG. 6, when the amount d of Pb (Zn 1/3 Nb 2/3 ) O 3 exceeds 65 mol%, K p and T c become low values, which is not preferable.
[0043]
The fifth inadequate matter is sample no. 15, no. When the ZnO amount e is less than 0.2 wt% with respect to the total weight of the main component as in No. 22, it is not preferable because giant voids are formed in the sintered body and the structure becomes inhomogeneous. 18, no. Even if it exceeds 2.5 wt% as in 25, the structure becomes inhomogeneous, which is not preferable.
[0044]
The sixth inappropriate matter is that of sample No. 21, no. When the PbO amount f exceeds 8 wt% as in No. 28, a huge void is generated, which is not preferable.
[0045]
By eliminating the sample corresponding to each of these inappropriate matters and the sample having deteriorated characteristics, the composition formula aPbTiO 3 + bPbZrO 3 + cPb (Mn 1/3 Nb 2/3 ) O 3 + dPb (Zn 1/3 Nb 2/3 ) In O 3 + eZnO + fPbO, a is 10 to 55 [mol%], b is 10 to 65 [mol%], c is 2 to 40 [mol%], and d is 0 to 65 [mol%] (provided that , A + b + c + d = 100) is added, and subcomponents with e being 0.2 to 2.5 [wt%] and f being 0 to 8 [wt%] based on the weight of the principal component are added. Thus, a piezoelectric ceramic material having high characteristics and capable of being fired at a low temperature of 1000 ° C. or lower can be obtained.
[0046]
That is, among the total of 30 types of samples shown in Table 2, sample No. 2, no. 3, No. 5, no. 7, no. 9, no. 11, no. 13, no. 16, no. 17, no. 19, no. 20, no. 23, no. 24, no. 26, no. 27, no. 29, no. Sample No. 30 is an example of the present invention. 1, No. 1 4, no. 6, no. 8, no. 10, no. 12, no. 14, no. 15, no. 18, no. 21, no. 22, no. 25, no. 28 is a comparative example outside the present invention.
[0047]
For each sample (sample No. 19, No. 20, No. 26, No. 27) shown in FIG. No. 19 shows that ZnO alone has an effect on lowering the sintering temperature even in the absence of Pb (Zn 1/3 Nb 2/3 ) O 3 . 19, no. 20, no. 26, no. 27 shows that the sintering temperature can be further reduced by adding PbO. Sample No. 29, no. It can be seen that a material having an excellent characteristic can be obtained with the composition of 30.
[0048]
【The invention's effect】
As described above, according to the present invention, PbTiO 3 , PbZrO 3 , Pb (Mn 1/3 E 2/3 ) O 3 (where E = Sb, Nb), Pb ( By using Zn 1/3 Nb 2/3 ) O 3 , ZnO, PbO in an appropriate amount range, it can be fired at a low temperature of 1000 ° C. or less which can avoid evaporation of PbO, and the relative dielectric constant ε r is 400 or more, coupling coefficient K p is 25 or more, the mechanical quality factor Q m is 500 or more, the Curie temperature T c is can be manufactured at low cost in energy saving piezoelectric material having excellent properties described above 200 ° C., industrial It will be beneficial to you.
[Brief description of the drawings]
FIG. 1 shows the relationship of the sintered body density to the sintering temperature for a representative one of the samples prepared in Example 1 illustrating the manufacturing process of the piezoelectric ceramic material of the present invention.
FIG. 2 shows the relationship of the sintered body density to the sintering temperature for a representative one of the samples prepared in Example 2 illustrating the manufacturing process of the piezoelectric ceramic material of the present invention.
Claims (2)
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