JP3562947B2 - Piezoelectric material - Google Patents
Piezoelectric material Download PDFInfo
- Publication number
- JP3562947B2 JP3562947B2 JP33415497A JP33415497A JP3562947B2 JP 3562947 B2 JP3562947 B2 JP 3562947B2 JP 33415497 A JP33415497 A JP 33415497A JP 33415497 A JP33415497 A JP 33415497A JP 3562947 B2 JP3562947 B2 JP 3562947B2
- Authority
- JP
- Japan
- Prior art keywords
- crystal
- piezoelectric material
- range
- atom selected
- valence
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
Description
【0001】
【発明の属する技術分野】
本発明は、共振器やフィルタなどの構成要素として用いられる新規な圧電体材料に関するものである。
【0002】
【従来の技術】
これまで、光学物性又は電気物性を利用したバルク単結晶材料としては、水晶やアルミナとともに不定比による固溶体領域をもった複合化合物、例えば希土類ガーネット、ニオブ酸リチウム、タンタル酸リチウム、ゲルマン酸ビスマス、ケイ酸ビスマスなどが知られている。
他方、最近Ca3Ga2Ge4O14型結晶構造をもつ圧電体材料が水晶と比較して大きな圧電特性を持ち、かつ水晶に近い圧電特性の温度安定性を有する材料として脚光を浴びている。
【0003】
これらの材料は、配位数8の原子のサイト、配位数6の原子のサイト及び2種類の配位数4の原子のサイトから構成されている。そして、本発明においては、配位数8の原子のサイトをA−サイト、配位数6の原子のサイトをB−サイト、配位数4の2種類の原子のサイトをそれぞれC−サイト及びD−サイトと称する。場合によっては、これらの各サイト間での陽イオンの置換も行われたものもあるし、また各サイトに空孔を有するものもある。
【0004】
ところで、このCa3Ga2Ge4O14型結晶構造を有する材料の中でLa3Ga5SiO14、Ca3Ga2Ge4O14及びSr3Ga2Ge4O14は、電気機械結合係数k12がそれぞれ0.16、0.145及び0.266であり、水晶の0.10よりも大きく上回ることが知られているし[1993年IEEE「インターナショナル・フリクエンシー・コントロール・シンポジウム(International Frequency Control Symposium)」,第351〜352ページ]、またBa3Ga2Ge4O14の圧電係数及び電気機械結合係数はSr3Ga2Ge4O14のそれらよりも大きいことが知られているので(同誌,第339〜347ページ)、好適な圧電体材料である。
【0005】
しかしながら、Sr3Ga2Ge4O14やBa3Ga2Ge4O14は、原料としてGa2O3やSiO2に比べ著しく高価なGeO2を用いなければならないため、コスト高になるのを免れないし、またそれらの融点付近すなわち1000℃以上の温度域でGeO2は高い蒸気圧を有するため、結晶成長時にGeO2が蒸散し、高品質の単結晶の成長がむずかしいという欠点を有しており、これが実用化を妨げている。
【0006】
【発明が解決しようとする課題】
本発明は、従来のCa3Ga2Ge4O14型結晶構造を有する圧電体材料のもつ欠点を克服し、結晶成長が容易で、低コストの、しかも優れた圧電特性を有する新らしいCa3Ga2Ge4O14型結晶構造の圧電体材料を提供しようとするものである。
【0007】
【課題を解決するための手段】
本発明者らは、Ca3Ga2Ge4O14型結晶構造をもつ圧電体材料について鋭意研究を重ねた結果、Ca、Ba、Sr及びPbの中から選ばれた少なくとも1種の元素、特にSrとBaの少なくとも一方を導入し、NbとTaとSbの中から選ばれた少なくとも1種の元素、かつGaとAlとFeの中から選ばれた少なくとも1種の元素及びそれ以外の元素からなる4種類以上の異なる陽イオンを組み合わせることにより、高価なGeO2の使用量を少なくして結晶成長時のGeO2の蒸散を減少させ、優れた圧電特性をもった単結晶が得られることを見い出し、この知見に基づいて本発明をなすに至った。
【0008】
すなわち、本発明は、価数2+で安定に存在し、配位数8をとることができ、この状態でのイオン半径が約1.1〜1.4Åの範囲にあるCa、Ba、Sr及びPbの中から選ばれた少なくとも1種の元素と、価数5+で安定に存在し、配位数6をとることができ、この状態でのイオン半径が約0.6〜0.7Åの範囲にあるNb、Ta及びSbの中から選ばれた少なくとも1種の元素と、価数3+で安定に存在し、配位数4をとることができ、この状態でのイオン半径が約0.3〜0.6Åの範囲にあるGa、Al及びFeの中から選ばれた少なくとも1種の元素と、それ以外の元素からなる4種類以上の異なる陽イオンと酸素イオンで構成されたCa3Ga2Ge4O14型結晶構造の化合物において、Ge含有率が0又は8.70atm%以下、CaとBaとSrとPbの中から選ばれた少なくとも1種の元素の含有率が4.35〜13.04atm%の範囲にあることを特徴とするものからなる圧電体材料を提供するものである。
【0009】
このCa3Ga2Ge4O14型結晶構造をもつ化合物は、少なくとも4種類の異なる陽イオンとなっている原子と陰イオンとなっている酸素原子の23個の原子から構成されているが、その中の2個以下すなわち8.70atm%以下がGeであり、CaとBaとSrとPbの中から選ばれた少なくとも1種が1個以上すなわち4.35atm%以上、好ましくは2個以上すなわち8.70atm%以上である。そして、これが3個の場合は13.04atm%になる。
【0010】
上記のGe、Ca、Ba、Sr及びPb以外の陽イオンとなっている原子については、Ca3Ga2Ge4O14型結晶構造中に置換可能なものであればよく特に制限はない。したがって、本発明の圧電体材料として用いうるものとしては、例えば一般式
M1 xM2 3−xM3M4 3+xM5 2−xO14 (I)
(式中のM1はLa、Pr、Nd及びBiの中から選ばれた少なくとも1種の原子、M2はCa、Sr、Ba及びPbの中から選ばれた少なくとも1種の原子、M3はNb、Ta及びSbの中から選ばれた少なくとも1種の原子、M4はGa、Al及びFeの中から選ばれた少なくとも1種の原子、M5はSi、Ge、Ti、Sn、Zr及びHfの中から選ばれた少なくとも1種の原子であり、xは0≦x≦2の数である)
で表わされる組成をもつCa3Ga2Ge4O14型結晶構造の化合物を挙げることができる。この一般式中のxは、0から1までの数が好ましく、最も好ましいのは0である。
【0011】
この一般式(I)において、M1及びM2で示される原子は、いずれも価数3+及び2+で安定に存在し、配位数8をとることができ、この状態でのイオン半径が約1.1〜1.4Åの範囲にあるものである。また、M3で示される原子は、いずれも価数5+で安定に存在し、配位数6をとることができ、この状態でのイオン半径が約0.6〜0.7Åの範囲にあるものである。次にM4及びM5で示される原子は、価数3+及び4+で安定に存在し、配位数4をとることができ、この状態でのイオン半径が約0.3〜0.6Åの範囲にあるものである。
【0012】
なお、ここにいうイオン半径とは、「アクタ・クリスタログラフィカ(Acta Crystallographica)」,1976年,第A32巻,第751〜767ページに記載されている有効イオン半径(IR effective ionic radius)を意味する。
Sr3Ga2Ge4O14やBa3Ga2Ge4O14の実用化を妨げる原因となっている原子のGeは、価数4+で安定であり、配位数4をとることからM5に属するが、このGeはM4やM5の中のGe以外の原子で置換することができるので、積極的にそれを行えば、コストを下げることができ、かつ結晶成長を容易に行いうるので、実用化が可能になる。
【0013】
本発明の圧電体材料は、安定なCa3Ga2Ge4O14型結晶構造を形成しているが、このCa3Ga2Ge4O14型結晶構造はASTM(JCPDS)カード36−0098に記載されている公知の結晶構造で、図1はこれをモデル的に表わした平面図である。なお、図中の(a)はB−サイト,(d)はC−サイト,(e)はA−サイト(f)はD−サイトの陽イオンとなっている原子の位置を示す。
【0014】
【発明の実施の形態】
本発明の圧電体材料を構成する化合物は、例えば前記一般式(I)を構成する元素の酸化物又は炭酸塩を、粉末状で所定の原子比になるように混合し、円柱状に圧縮成形したのち、大気中、1000〜1500℃で焼結し、気密性の保たれた結晶引き上げ装置内で、少量の酸素を含む窒素雰囲気下に融解し、常法、例えばチョクラルスキー(Czochralski)法により、結晶成長させることによって製造することができる。この際の成長条件としては、通常結晶回転数1〜100rpm、好ましくは5〜50rpm、種結晶引き上げ速度0.1〜10mm/hr、好ましくは0.5〜5mm/hrである。このようにして直径約25mm、長さ約70mmまでの無色透明な単結晶を得ることができる。この結晶の同定は、その一部を粉砕し、粉末X線回折し、その回折ピークを対比することによって行うことができる。
このようにして得られる単結晶は、重量変化率(ΔW/W1)が0.4%以下と小さく、電気機械結合係数(k12)が0.17以上と大きかった。
【0015】
【実施例】
次に、実施例によって本発明をさらに詳細に説明する。なお、各例中の重量変化率及び電気機械結合係数は、以下の方法により求めた。
【0016】
(1)重量変化率
結晶成長開始直前の原料が充填された状態でるつぼ重量を秤量し、これをW1とする。次に結晶成長終了直後の、原料が残存した状態でのるつぼ重量を秤量し、これをW2とする。結晶成長により得た結晶の重量をW3とすると、結晶成長中に蒸散した原料の量ΔWは以下のとおりになる。
ΔW=W1−(W2+W3)
したがって、重量変化率W(%)は、
W(%)=ΔW/W1×100
として求められる。
【0017】
(2)電気機械結合係数
単結晶から15×2.5×0.5mmの板状体を作成し、15×2.5mmの面にアルミニウムを蒸着して電極面とした。この電極面は結晶方位のx面に対し平行であり、板状体長手方向が結晶方位y軸に対し、平行となるように切り出した。次いで、この試料電極面に交流電界を印加し、IREの標準回路の方法に従い共振周波数(ωR)と反共振周波数(ωA)とを測定し、次式から電気機械結合係数k12を求めた。
【0018】
【数1】
【0019】
実施例1
純度99%以上のSrCO3とTa2O5とGa2O3とSiO2とを原子比でSr:Ta:Ga:Siが3:1:3:2になるように混合し、これを円柱状に圧縮して約1450℃において大気雰囲気で焼結させた。この焼結体を、直径50mm、高さ50mm及び厚さ1.5mmのイリジウムるつぼに入れ、気密性の保たれた結晶引き上げ装置内で、2vol%の酸素を含む窒素雰囲気下で、誘導加熱して融解した。結晶の成長行程は、チョクラルスキー法による既知の方法で行い、結晶回転数5rpm、種結晶引き上げ速度を1.5mm/hrの条件で、長さ68mm、直径24mmの無色透明な単結晶を得た。
結晶の一部を粉砕して粉末X線回折による相同定を行った結果、回折ピークは全てCa3Ga2Ge4O14構造を有する相として指数付けでき、その他の異相ピークは全く認められず単一相であることが確認できた。
結晶の表面状態は、荒れ、異物質の付着等は認められず、滑らかで光沢が認められる。結晶内に、気泡、割れ及びインクルージョンなどの巨視的な欠陥は認められず、偏光顕微鏡によるオルソスコープ像から均一な単結晶になっていることが分った。この単結晶は、水晶とほぼ同程度の硬度であり、室温付近で化学的、物理的に安定である。また、水晶等で用いられる通常の加工条件で、クラック発生等の問題もなく、結晶切断及び研磨ができ、結晶の取り扱いが容易であることが分った。このものの結晶成長前後での重量変化率ΔW/W1は、0.1%、電気機械結合係数k12は0.25であった。
【0020】
実施例2
純度99%以上のBaCO3とTa2O5とGa2O3とSiO2とを原子比でBa:Ta:Ga:Siが3:1:3:2になるように混合し、これを円柱状に圧縮して大気雰囲気中で約1300℃において焼結した。実施例1と同じ条件で、結晶成長を行い、長さ33mm、直径25mmの無色透明な単結晶を得た。
この結晶は、Ca3Ga2Ge4O14構造の単一相であり、表面に荒れ、異物質の付着等はなく、滑らかで光沢が認められる。結晶内に、気泡、割れ及びインクルージョンなどの巨視的な欠陥は認められず、均一な単結晶であることを確認した。また、結晶成長前後での重量変化率ΔW/W1は0.4%であり、成長中の蒸散はほとんどなかった。また、この材料の電気機械結合係数k12は0.29と大きな値を示した。
【0021】
実施例3
純度99%以上のLa2O3とSrCO3とTa2O5とGa2O3とSiO2とを原子比でLa:Sr:Ta:Ga:Siが1:2:1:4:1になるように混合し、これを円柱状に圧縮して約1300℃において大気雰囲気で焼結した。実施例1と同じ条件で、結晶成長を行い、長さ39mm、直径22mmのわずかに黄色を呈した透明な単結晶を得た。
この結晶は、Ca3Ga2Ge4O14構造の単一相であり、表面に荒れ、異物質の付着等はなく、滑らかで光沢が認められる。結晶内に、気泡、割れ及びインクルージョンなどの巨視的な欠陥は認められず、均一な単結晶であることを確認した。また、結晶成長前後での重量変化率ΔW/W1は0.2%であった。また、この材料の電気機械結合係数k12は0.20であった。
【0022】
実施例4
純度99%以上のLa2O3とSrCO3とTa2O5とGa2O3とを原子比でLa:Sr:Ta:Gaが2:1:1:5になるように混合し、これを円柱状に圧縮して約1300℃において大気雰囲気で焼結した。実施例1と同じ条件で、結晶成長を行い、長さ34mm、直径23mmの無色透明な単結晶を得た。
この結晶は、Ca3Ga2Ge4O14構造の単一相であり、表面に荒れ、異物質の付着等はなく、滑らかで光沢が認められる。結晶内に、気泡、割れ及びインクルージョンなどの巨視的な欠陥は認められず、均一な単結晶であることを確認した。また、結晶成長前後での重量変化率ΔW/W1は0.3%であった。また、この材料の電気機械結合係数k12は0.17であった。
【0023】
比較例
純度4NのSrCO3とGa2O3とGeO2とを原子比でSr:Ga:Geが3:2:4になるように混合し、これを約1300℃において酸素雰囲気で焼結した。この焼結体を、直径50mm、高さ50mm及び厚さ1.5mmの白金るつぼに入れ、結晶引き上げ装置内で、誘導加熱して融解した。結晶の成長行程は、チョクラルスキー法による既知の方法で行い、GeO2の蒸散を抑制する目的で、酸素雰囲気を選択した。結晶回転数10rpm、種結晶引き上げ速度を1mm/hrの条件で、長さ32mm、直径18mmのわずかに黄色味を帯びた結晶を得た。
結晶の表面状態は、全体的にしわ状に荒れ、黒い粒状の白金と思われる付着物が認められた。特に、結晶後半部に割れ及びインクルージョンなどの巨視的な欠陥が多く存在している。この結晶からは、実施例1に示す大きさの圧電特性測定用の試料を作成することができなかった。
結晶成長前後での重量変化率ΔW/W1は2.6%で、成長中の原料蒸散量が非常に多かった。
【0024】
【発明の効果】
本発明によれば、高価なGeの使用量が少なく、しかも結晶成長を容易に行うことができ、優れた圧電特性を有する実用化可能な圧電体材料が提供される。
【図面の簡単な説明】
【図1】Ca3Ga2Ge4O14型結晶構造のモデルの平面図。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a novel piezoelectric material used as a component such as a resonator or a filter.
[0002]
[Prior art]
Heretofore, as bulk single crystal materials utilizing optical or electrical properties, complex compounds having a non-stoichiometric solid solution region together with quartz or alumina, such as rare earth garnet, lithium niobate, lithium tantalate, bismuth germanate, silica Bismuth acid and the like are known.
On the other hand, recently, a piezoelectric material having a Ca 3 Ga 2 Ge 4 O 14 type crystal structure has attracted attention as a material having large piezoelectric characteristics as compared with quartz and having temperature stability of piezoelectric characteristics close to quartz. .
[0003]
These materials are composed of eight coordination atoms, two coordination atoms, and two coordination four atoms. In the present invention, a site of an atom having a coordination number of 8 is an A-site, a site of an atom having a coordination number of 6 is a B-site, and a site of two kinds of atoms having a coordination number of 4 is a C-site and Called D-site. In some cases, cations are substituted between these sites, and some have vacancies at each site.
[0004]
Incidentally, among the materials having the Ca 3 Ga 2 Ge 4 O 14 type crystal structure, La 3 Ga 5 SiO 14 , Ca 3 Ga 2 Ge 4 O 14 and Sr 3 Ga 2 Ge 4 O 14 have electromechanical coupling coefficients. k 12 are each 0.16,0.145 and 0.266, to have been known to exceed greater than 0.10 of the crystal [1993 IEEE "International FrequenSea control Symposium (International Frequency control Symposium) ", the 351-352 pages, and since the piezoelectric coefficients and electromechanical coupling coefficient of Ba 3 Ga 2 Ge 4 O 14 it is known is larger than those of Sr 3 Ga 2 Ge 4 O 14 ( The same magazine, pp. 339-347), suitable piezoelectric It is a material.
[0005]
However, Sr 3 Ga 2 Ge 4 O 14 or Ba 3 Ga 2 Ge 4 O 14 requires GeO 2, which is significantly more expensive than Ga 2 O 3 or SiO 2 , as a raw material. GeO 2 has a high vapor pressure near its melting point, that is, at a temperature range of 1000 ° C. or higher, and GeO 2 evaporates during crystal growth, which makes it difficult to grow a high-quality single crystal. This hinders practical application.
[0006]
[Problems to be solved by the invention]
The present invention overcomes the drawbacks of the conventional piezoelectric material having a Ca 3 Ga 2 Ge 4 O 14 type crystal structure, and facilitates crystal growth, is low cost, and has a new Ca 3 having excellent piezoelectric characteristics. An object of the present invention is to provide a piezoelectric material having a Ga 2 Ge 4 O 14 type crystal structure.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on a piezoelectric material having a Ca 3 Ga 2 Ge 4 O 14 type crystal structure, and as a result, at least one element selected from Ca, Ba, Sr and Pb, in particular, At least one of Sr and Ba is introduced, and at least one element selected from Nb, Ta, and Sb, and at least one element selected from Ga, Al, and Fe and other elements are used. By combining four or more different cations, the amount of expensive GeO 2 used is reduced, the evaporation of GeO 2 during crystal growth is reduced, and a single crystal having excellent piezoelectric properties can be obtained. The present inventors have found out the present invention based on this finding.
[0008]
That is, in the present invention, Ca , Ba , Sr, and cations having a valence of 2+ and having a coordination number of 8 and having an ionic radius in the range of about 1.1 to 1.4 ° can be obtained. and at least one element selected from among pb, stably exist in a valence 5+ may take a coordination number of 6, the range ionic radius at this state is about 0.6~0.7Å and at least one element Nb, selected from among Ta and Sb in stably present in valence 3+, can take a coordination number of 4, the ion radius in this state is about 0.3 and at least one element selected Ga in the range of ~0.6A, from among Al and Fe, Ca 3 Ga 2 constituted by four or more different cations and oxygen ions consisting of the other elements in the compounds of Ge 4 O 14 type crystal structure, Ge content of 0 or 8.70 tm% or less, the piezoelectric material content of at least one element selected from among Ca, Ba and Sr and Pb is made from those being in the range of 4.35 ~13.04 atm% Is provided.
[0009]
The compound having the Ca 3 Ga 2 Ge 4 O 14 type crystal structure is composed of at least four kinds of 23 different cation atoms and 23 different anion oxygen atoms. Two or less thereof, ie, 8.70 atm% or less, is Ge, and at least one selected from Ca, Ba, Sr, and Pb is one or more, ie, 4.35 atm% or more, preferably two or more, 8.70 atm% or more . When the number is three, it is 13.04 atm%.
[0010]
The cation atoms other than Ge, Ca, Ba, Sr and Pb are not particularly limited as long as they can be substituted in the Ca 3 Ga 2 Ge 4 O 14 type crystal structure. Thus, those usable as the piezoelectric material of the present invention, for example formula M 1 x M 2 3-x M 3 M 4 3 + x M 5 2-x O 14 (I)
(Where M 1 is at least one atom selected from La, Pr, Nd and Bi, M 2 is at least one atom selected from Ca, Sr, Ba and Pb, M 3 Is at least one atom selected from Nb, Ta, and Sb; M 4 is at least one atom selected from Ga, Al, and Fe; and M 5 is Si, Ge, Ti, Sn, Zr. And at least one atom selected from Hf, and x is a number satisfying 0 ≦ x ≦ 2)
And a compound having a Ca 3 Ga 2 Ge 4 O 14 type crystal structure having a composition represented by the following formula: X in this general formula is preferably a number from 0 to 1, and most preferably 0.
[0011]
In this general formula (I), the atoms represented by M 1 and M 2 are both stably present with valences of 3+ and 2+, can take a coordination number of 8, and the ionic radius in this state is about 1.1 to 1.4 °. Furthermore, atom represented by M 3 are both stably present in valence 5+ may take a coordination number of 6, the ion radius in this state is in the range of about 0.6~0.7Å Things. Next, the atoms represented by M 4 and M 5 are stably present with valences of 3+ and 4+, can assume a coordination number of 4, and have an ionic radius of about 0.3 to 0.6 ° in this state. Are in range.
[0012]
The ionic radius referred to herein means an effective ionic radius described in "Acta Crystallographica", 1976, Vol. A32, pp. 751-767. .
Ge, which is an atom that hinders the practical use of Sr 3 Ga 2 Ge 4 O 14 and Ba 3 Ga 2 Ge 4 O 14 , is stable at a valence of 4+, and has a coordination number of 4 and therefore, M 5. However, this Ge can be replaced with an atom other than Ge in M 4 or M 5. Therefore, if this is positively performed, the cost can be reduced and the crystal can be easily grown. Therefore, practical use becomes possible.
[0013]
The piezoelectric material of the present invention forms a stable Ca 3 Ga 2 Ge 4 O 14 type crystal structure, and this Ca 3 Ga 2 Ge 4 O 14 type crystal structure is applied to an ASTM (JCPDS) card 36-0098. FIG. 1 is a plan view schematically showing this known crystal structure. In the figure, (a) shows the position of the B-site, (d) shows the C-site, (e) shows the A-site (f) shows the position of the cation of the D-site.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
The compound constituting the piezoelectric material of the present invention is obtained, for example, by mixing oxides or carbonates of the elements constituting the general formula (I) in a powder form so as to have a predetermined atomic ratio, and compression-molding the mixture into a columnar shape. After that, it is sintered at 1000 to 1500 ° C. in the air and melted in a nitrogen pulling apparatus containing a small amount of oxygen in a crystal pulling apparatus which is kept airtight, and is subjected to a conventional method such as a Czochralski method. Can be produced by crystal growth. The growth conditions at this time are generally a crystal rotation speed of 1 to 100 rpm, preferably 5 to 50 rpm, and a seed crystal pulling rate of 0.1 to 10 mm / hr, preferably 0.5 to 5 mm / hr. Thus, a colorless and transparent single crystal having a diameter of about 25 mm and a length of about 70 mm can be obtained. The identification of the crystal can be performed by crushing a part thereof, performing X-ray powder diffraction, and comparing the diffraction peaks.
The single crystal thus obtained had a small weight change rate (ΔW / W 1 ) of 0.4% or less and a large electromechanical coupling coefficient (k 12 ) of 0.17 or more.
[0015]
【Example】
Next, the present invention will be described in more detail with reference to examples. The weight change rate and the electromechanical coupling coefficient in each example were determined by the following methods.
[0016]
(1) were weighed crucible weight in a state in which the weight change ratio crystal growth immediately before the material is filled, which is referred to as W 1. Immediately after the completion of the crystal growth then, the raw material is weighed crucible weight while remaining This is referred to as W 2. When the weight of the crystal obtained by crystal growth and W 3, the amount ΔW of raw material vaporized during crystal growth is as follows.
ΔW = W 1 − (W 2 + W 3 )
Therefore, the weight change rate W (%) is
W (%) = ΔW / W 1 × 100
Is required.
[0017]
(2) Electromechanical Coupling Coefficient A plate having a size of 15 × 2.5 × 0.5 mm was prepared from a single crystal, and aluminum was deposited on a surface of 15 × 2.5 mm to form an electrode surface. The electrode face was parallel to the x-plane of the crystal orientation, and the plate was cut out so that the longitudinal direction was parallel to the y-axis of the crystal orientation. Then, this sample electrode surface by applying an alternating electric field, the a standard circuit method according resonant frequency of the IRE (omega R) and the anti-resonance frequency (omega A) was measured to obtain the electromechanical coupling factor k 12 from the following equation Was.
[0018]
(Equation 1)
[0019]
Example 1
SrCO 3 , Ta 2 O 5 , Ga 2 O 3, and SiO 2 having a purity of 99% or more are mixed in an atomic ratio such that Sr: Ta: Ga: Si becomes 3: 1: 3: 2, and this is circled. It was compressed into a columnar shape and sintered at about 1450 ° C. in an air atmosphere. This sintered body was placed in an iridium crucible having a diameter of 50 mm, a height of 50 mm, and a thickness of 1.5 mm, and was subjected to induction heating in a nitrogen pulling apparatus containing 2 vol% of oxygen in an airtight crystal pulling apparatus. Melted. The crystal growth process is performed by a known method by the Czochralski method, and a colorless and transparent single crystal having a length of 68 mm and a diameter of 24 mm is obtained at a crystal rotation speed of 5 rpm and a seed crystal pulling speed of 1.5 mm / hr. Was.
As a result of performing phase identification by powder X-ray diffraction by crushing a part of the crystal, all diffraction peaks can be indexed as a phase having a Ca 3 Ga 2 Ge 4 O 14 structure, and no other heterophase peaks are observed. It was confirmed that it was a single phase.
The surface condition of the crystal is smooth and glossy without any roughening or attachment of foreign substances. No macroscopic defects such as bubbles, cracks and inclusions were found in the crystal, and it was found from an orthoscopic image by a polarizing microscope that the crystal was a uniform single crystal. This single crystal has almost the same hardness as quartz and is chemically and physically stable around room temperature. In addition, it was found that under normal processing conditions used for quartz and the like, there was no problem such as crack generation, crystal cutting and polishing could be performed, and crystal handling was easy. Weight change ratio [Delta] W / W 1 in the crystal growth before and after this compound, 0.1%, the electromechanical coupling factor k 12 was 0.25.
[0020]
Example 2
BaCO 3 , Ta 2 O 5 , Ga 2 O 3, and SiO 2 having a purity of 99% or more are mixed at an atomic ratio of Ba: Ta: Ga: Si of 3: 1: 3: 2, and this is mixed with a circle. It was compressed into a columnar shape and sintered at about 1300 ° C. in an air atmosphere. Crystal growth was performed under the same conditions as in Example 1 to obtain a colorless and transparent single crystal having a length of 33 mm and a diameter of 25 mm.
This crystal is a single phase having a Ca 3 Ga 2 Ge 4 O 14 structure, has no roughness on its surface, has no foreign substances attached thereto, and is smooth and glossy. No macroscopic defects such as bubbles, cracks and inclusions were found in the crystal, and it was confirmed that the crystal was a uniform single crystal. The weight change rate [Delta] W / W 1 before and after crystal growth is 0.4%, transpiration during growth was little. Further, the electromechanical coupling coefficient k 12 of this material showed a large value of 0.29.
[0021]
Example 3
La: Sr: Ta: Ga: Si having an atomic ratio of La 2 O 3 , SrCO 3 , Ta 2 O 5 , Ga 2 O 3, and SiO 2 having a purity of 99% or more is 1: 2: 1: 4: 1. The resulting mixture was compressed into a columnar shape and sintered at about 1300 ° C. in an air atmosphere. Crystal growth was carried out under the same conditions as in Example 1 to obtain a slightly yellow transparent single crystal having a length of 39 mm and a diameter of 22 mm.
This crystal is a single phase having a Ca 3 Ga 2 Ge 4 O 14 structure, has no roughness on its surface, has no foreign substances attached thereto, and is smooth and glossy. No macroscopic defects such as bubbles, cracks and inclusions were found in the crystal, and it was confirmed that the crystal was a uniform single crystal. The weight change rate [Delta] W / W 1 before and after the crystal growth was 0.2%. Further, the electromechanical coupling coefficient k 12 of this material was 0.20.
[0022]
Example 4
La 2 O 3 , SrCO 3 , Ta 2 O 5, and Ga 2 O 3 having a purity of 99% or more are mixed at an atomic ratio of La: Sr: Ta: Ga of 2: 1: 1: 5. Was compressed into a columnar shape and sintered at about 1300 ° C. in an air atmosphere. Crystal growth was performed under the same conditions as in Example 1 to obtain a colorless and transparent single crystal having a length of 34 mm and a diameter of 23 mm.
This crystal is a single phase having a Ca 3 Ga 2 Ge 4 O 14 structure, has no roughness on its surface, has no foreign substances attached thereto, and is smooth and glossy. No macroscopic defects such as bubbles, cracks and inclusions were found in the crystal, and it was confirmed that the crystal was a uniform single crystal. The weight change rate [Delta] W / W 1 before and after the crystal growth was 0.3%. Further, the electromechanical coupling coefficient k 12 of this material was 0.17.
[0023]
Comparative Example SrCO 3 , Ga 2 O 3, and GeO 2 having a purity of 4N were mixed in an atomic ratio of Sr: Ga: Ge of 3: 2: 4, and this was sintered at about 1300 ° C. in an oxygen atmosphere. . The sintered body was placed in a platinum crucible having a diameter of 50 mm, a height of 50 mm and a thickness of 1.5 mm, and was melted by induction heating in a crystal pulling apparatus. The crystal growth process was performed by a known method using the Czochralski method, and an oxygen atmosphere was selected for the purpose of suppressing the evaporation of GeO 2 . A slightly yellowish crystal having a length of 32 mm and a diameter of 18 mm was obtained at a crystal rotation speed of 10 rpm and a seed crystal pulling speed of 1 mm / hr.
The surface state of the crystal was entirely roughened in the form of wrinkles, and deposits considered to be black granular platinum were observed. In particular, there are many macroscopic defects such as cracks and inclusions in the latter half of the crystal. A sample for measuring the piezoelectric characteristics having the size shown in Example 1 could not be prepared from this crystal.
Weight change ratio [Delta] W / W 1 before and after crystal growth is 2.6%, the raw material transpiration of growing was very large.
[0024]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the usage-amount of expensive Ge is small, crystal growth can be performed easily, and the piezoelectric material which can be used practically and has excellent piezoelectric characteristics is provided.
[Brief description of the drawings]
FIG. 1 is a plan view of a model of a Ca 3 Ga 2 Ge 4 O 14 type crystal structure.
Claims (4)
M1 xM2 3−xM3M4 3+xM5 2−xO14
(式中のM1はLa、Pr、Nd及びBiの中から選ばれた少なくとも1種の原子、M2はCa、Ba、Sr及びPbの中から選ばれた少なくとも1種の原子、M3はNb、Ta及びSbの中から選ばれた少なくとも1種の原子、M4はGa、Al及びFeの中から選ばれた少なくとも1種の原子、M5はSi、Ge、Ti、Sn、Zr及びHfの中から選ばれた少なくとも1種の原子であり、xは0≦x≦2の数である)
で表わされる組成をもつCa3Ga2Ge4O14型結晶構造の化合物からなる圧電体材料。Formula M 1 x M 2 3-x M 3 M 4 3 + x M 5 2-x O 14
(Wherein M 1 is at least one atom selected from La, Pr, Nd and Bi, M 2 is at least one atom selected from Ca, Ba, Sr and Pb, M 3 Is at least one atom selected from Nb, Ta, and Sb; M 4 is at least one atom selected from Ga, Al, and Fe; and M 5 is Si, Ge, Ti, Sn, Zr. And at least one atom selected from Hf, and x is a number satisfying 0 ≦ x ≦ 2)
A piezoelectric material comprising a compound having a Ca 3 Ga 2 Ge 4 O 14 type crystal structure having a composition represented by the following formula:
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP33415497A JP3562947B2 (en) | 1997-12-04 | 1997-12-04 | Piezoelectric material |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP33415497A JP3562947B2 (en) | 1997-12-04 | 1997-12-04 | Piezoelectric material |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH11171696A JPH11171696A (en) | 1999-06-29 |
JP3562947B2 true JP3562947B2 (en) | 2004-09-08 |
Family
ID=18274147
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP33415497A Expired - Lifetime JP3562947B2 (en) | 1997-12-04 | 1997-12-04 | Piezoelectric material |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP3562947B2 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2000016478A1 (en) * | 1998-09-14 | 2000-03-23 | Tdk Corporation | Surface acoustic wave device |
US6413442B2 (en) | 2000-05-22 | 2002-07-02 | Tdk Corporation | Method of producing single crystal and piezoelectric element |
JP4748170B2 (en) * | 2008-02-08 | 2011-08-17 | Tdk株式会社 | Piezoelectric single crystal material and piezoelectric device using the piezoelectric single crystal material |
JP6369977B2 (en) * | 2014-05-07 | 2018-08-08 | 株式会社Piezo Studio | Piezoelectric vibrator |
-
1997
- 1997-12-04 JP JP33415497A patent/JP3562947B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JPH11171696A (en) | 1999-06-29 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Mulvihill et al. | The role of processing variables in the flux growth of lead zinc niobate-lead titanate relaxor ferroelectric single crystals | |
KR100852536B1 (en) | Piezoelectric single crystal, piezoelectric single crystal element and method for preparation thereof | |
Tuttle et al. | Solution deposition of ferroelectric thin films | |
JP5156065B2 (en) | Piezoelectric single crystal element | |
KR100628812B1 (en) | Piezoelectric Single Crystal Device and Fabrication Method Thereof | |
CN100448048C (en) | Piezoelectric single crystal element and method for fabricating the same | |
JP6185441B2 (en) | Piezoelectric single crystal and piezoelectric single crystal element | |
JP3562947B2 (en) | Piezoelectric material | |
JP4268111B2 (en) | Piezoelectric single crystal, piezoelectric single crystal element, manufacturing method thereof, and 1-3 composite piezoelectric element | |
JP4568529B2 (en) | Piezoelectric single crystal element | |
JP4508725B2 (en) | Piezoelectric single crystal element and manufacturing method thereof | |
JP4658773B2 (en) | Piezoelectric single crystal element | |
Fukuda et al. | Growth of new langasite single crystals for piezoelectric applications | |
Takeda et al. | Growth and characterization of lanthanum calcium oxoborate LaCa4O (BO3) 3 single crystals | |
Takeda et al. | Growth and piezoelectric properties of R3Ga5SiO14 and RCa4O (BO3) 3 (R: rare-earth elements) single crystals | |
CN1196817C (en) | Growth of high curie point lead niobate lead indate-lead titanate single crystal using crucible descending method | |
CN107925399B (en) | Substrate for surface acoustic wave element and method for manufacturing the same | |
JP6186099B1 (en) | Surface acoustic wave device substrate and method of manufacturing the same | |
EP0834605B1 (en) | Oxide single crystal and method of manufacturing thereof | |
Shimizu et al. | Evaluation of material constants and SAW properties in LaCa/sub 4/O (BO/sub 3/)/sub 3/single crystals | |
JP3835286B2 (en) | Piezoelectric material, substrate for piezoelectric device, and surface acoustic wave device | |
JP2010138066A (en) | Production method of ferroelectric crystal having bismuth layered structure | |
JP4494028B2 (en) | Bismuth layered structure ferroelectric crystal, manufacturing method thereof, and electronic device using the same | |
JPS604583B2 (en) | Magnetic device with single crystal garnet substrate with magnetic layer | |
Xiuwei | Influence of Oxygen Partial Pressure and Al Content on the Resistivity and Piezoelectric Properties of Ca3TaGa3-xAlxSi2O14 Single Crystals |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20040129 |
|
A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20040329 |
|
A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20040330 |
|
TRDD | Decision of grant or rejection written | ||
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20040527 |
|
A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20040601 |
|
R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080611 Year of fee payment: 4 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090611 Year of fee payment: 5 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090611 Year of fee payment: 5 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100611 Year of fee payment: 6 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110611 Year of fee payment: 7 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120611 Year of fee payment: 8 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120611 Year of fee payment: 8 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130611 Year of fee payment: 9 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140611 Year of fee payment: 10 |
|
EXPY | Cancellation because of completion of term |