JPS6022513B2 - piezoelectric porcelain - Google Patents

Description

【発明の詳細な説明】 本発明は、電気機械結合係数が大きく、誘電率が小さく
周波数定数が大きく、さらに結晶粒子径が小さくて均一
で微細な磁器組織を持ち、高周波での電気機械変換素子
として有用な圧電性磁器に関する。Detailed Description of the Invention The present invention provides an electromechanical transducer that has a large electromechanical coupling coefficient, a small dielectric constant, a large frequency constant, a small crystal grain size, and a uniform and fine porcelain structure, and which can be used at high frequencies. This invention relates to piezoelectric porcelain useful as a material.

従釆、圧電性磁器としてチタン酸バリウム系磁器ジルコ
ン・チタン酸鉛系磁器が知られている。Additionally, barium titanate-based porcelain and zircon/lead titanate-based porcelain are known as piezoelectric porcelain.

特にジルコン・チタン酸鉛系磁器は電気機械結合係数（
Ｋ）、誘電率（ど）が大きく、電気機械変換素子として
多方面で実用されている。ところで最近電子回路の発達
から高周波域特に数Ｍ位以上で使用できる電気機械変換
素子の出現が強く要望されている。In particular, zircon-lead titanate-based porcelain has an electromechanical coupling coefficient (
It has a large dielectric constant (K) and a large dielectric constant (d), and is used in many fields as an electromechanical transducer. Recently, with the development of electronic circuits, there has been a strong demand for an electromechanical transducer that can be used in a high frequency range, particularly in a range of several megawatts or more.

従来のチタン酸バリウム系磁器、ジルコン・チタン酸鉛
系磁器では誘電率が大きい為にかかる高周波城では損失
が大きくなる。又、周波数定数が小さい為にかかる高周
波城で実用する場合、素子の厚味を極〈薄くする等非常
な小寸法の素子とすることが必要となり、実用上良好な
結果を得ていない。これらの点を解決する組成物として
ＮａＮｂｏ３一ＬｉＮｂｏ３系固溶体が見出されている
。Conventional barium titanate-based porcelain and zircon-lead titanate-based porcelain have large dielectric constants, so losses are large in such high-frequency applications. In addition, since the frequency constant is small, when it is put into practical use in such a high-frequency device, it is necessary to make the device very small in size, such as by making the thickness of the device extremely thin, and good results have not been obtained in practice. A solid solution based on NaNbo3-LiNbo3 has been found as a composition that solves these problems.

これらの組成物は譲霞率が小さく、高周波定数が大きい
特徴を有している。しかし、これらの組成物は磁器組織
として微細で均一なものが得難い。すなわち、暁結に適
する温度範囲が狭い為に異状粒成長が起きやすく、結晶
粒子径が大きくかつ不均一となりさらに気孔を多く残存
させる。ところで高周波城では、これらの磁器組織の不
均一性は電気機械変換素子としての性能を箸るしく低下
させ、さらに結晶粒子径が大きいことが素子としての強
度、特にかかる高周波用として必要な小寸法での強度を
極めて低下させ、これらのことが実用上大きな障害とな
っている。These compositions are characterized by a low yield factor and a large high frequency constant. However, with these compositions, it is difficult to obtain a fine and uniform porcelain structure. That is, since the temperature range suitable for crystallization is narrow, abnormal grain growth is likely to occur, resulting in large and non-uniform crystal grain sizes, and furthermore, many pores remain. By the way, in high frequency castles, the non-uniformity of these porcelain structures significantly reduces the performance as an electromechanical transducer, and the large crystal grain size also reduces the strength of the element, especially the small size required for such high frequencies. These problems pose a major obstacle in practical use.

これらの点を解決する方法として特殊な製造方法、例え
ばホットプレス法による焼結等が見し、出されているが
、それでも焼結温度等の条件範囲は狭くて充分な結果は
得られず、かつ製造方法を複雑にすることから実用上好
ましくない。Special manufacturing methods such as hot press sintering have been proposed as a way to solve these problems, but even then, the range of conditions such as sintering temperature is narrow and satisfactory results cannot be obtained. In addition, it complicates the manufacturing method, which is not preferred in practice.

本発明は上記の様な従来のものの欠点を除去し、高周波
域電気機械変換子として利用できる全く新しい圧電性磁
器を提供するものである。即ち、本発明は一般式（Ｎａ
，★，Ｌｉｘ）（ＮＬ‐ｙ，ＳＱ）０３〔１〕で示され
×，ｙの値が０．０３＜×＜０．１４，０．００１＜ｙ
＜０．０３の範囲の組成を有する圧電性磁器である。本
発明による圧電性磁器は、通常の焼成方法によって結晶
粒子径の小さい、均一微細な磁器組織が得られさらに電
気機械結合係数が大きく、誘電率が小さく周波数定数が
大きい特徴を有し、高周波城特にＭ位以上でその電気機
械変換素子として実用するに好適な材料である。第１図
に本発明になる圧電性磁器の組成範囲を示した。The present invention eliminates the above-mentioned drawbacks of the conventional piezoelectric ceramics and provides a completely new piezoelectric ceramic that can be used as a high-frequency electromechanical transducer. That is, the present invention is based on the general formula (Na
,★,Lix)(NL-y,SQ)03[1], and the value of ×,y is 0.03<x<0.14,0.001<y
Piezoelectric porcelain with a composition in the range <0.03. The piezoelectric porcelain according to the present invention has the characteristics that a uniform fine porcelain structure with small crystal grain size can be obtained by a normal firing method, a large electromechanical coupling coefficient, a small dielectric constant, a large frequency constant, and high frequency resistance. In particular, it is a suitable material for practical use as an electromechanical transducer at the M position or higher. FIG. 1 shows the composition range of the piezoelectric ceramic according to the present invention.

図中のｘ，ｙは〔１〕式のｘ，ｙに対応し番号は後述す
る第１表の試料番号に対応している。ここで本発明の圧
電性磁器は図中の４点Ａ，Ｂ，Ｃ，Ｄで囲まれる範囲、
即ち０．０３＜文＜０．１４０．００１＜ｙ＜０．０３
に限定され、特に結晶粒子径、誘電率の点から０．０３
＜×＜０．１０では０．００２＜ｙｏ．０１が、０．１
び＜×＜０．１４では０．００２ミｙミ０．０３が望ま
しい。x and y in the figure correspond to x and y in formula [1], and the numbers correspond to sample numbers in Table 1, which will be described later. Here, the piezoelectric porcelain of the present invention has a range surrounded by four points A, B, C, and D in the figure.
That is, 0.03<text<0.140.001<y<0.03
0.03, especially from the point of view of crystal grain size and dielectric constant.
<x<0.10, 0.002<yo. 01 is 0.1
When <×<0.14, 0.002 mm and 0.03 are desirable.

本発明における組成限定の理由はｘ＜０．０３では分極
処理に要する印加電圧が極めて大きくなり、実用に供す
ることは難しい。他方又＞０．１４では単一相からなる
焼縞体が得られず濠相となり、所定の圧電停性を示さな
い。又、ｙ＜０．００１では暁結が極めて進みやすく凝
結過程において結晶粒の成長が進展して結晶粒子径が１
０山を超えて、さらに異状粒成長を起す為通常の競結方
法では均一な磁器組成が縛られない。他方ｙ＞０．０３
では、ｙく０．００１と同様に均一な磁器組織が得られ
ない。本発明の圧電性磁器を製造するには、例えばＮａ
２ＣＱ，Ｌｊ２Ｃ０３，Ｎｂ２０３，Ｓｂ２０３の様な
成分原料を所定量、秤量、混合しその混合物を８００〜
１，０００つ０で２〜８時間仮暁する。The reason for the composition limitation in the present invention is that when x<0.03, the applied voltage required for polarization treatment becomes extremely large, making it difficult to put it to practical use. On the other hand, if it is >0.14, a burnt striped body consisting of a single phase is not obtained, but a moat phase is obtained, and the predetermined piezostatic property is not exhibited. In addition, when y<0.001, crystal grains grow very easily during the solidification process, and the crystal grain size decreases to 1.
Since abnormal grain growth occurs beyond the zero peak, a uniform porcelain composition cannot be secured by the normal competitive bonding method. On the other hand y>0.03
In this case, a uniform porcelain structure cannot be obtained as in the case where y is 0.001. To produce the piezoelectric porcelain of the present invention, for example, Na
2CQ, Lj2C03, Nb203, Sb203 and other component raw materials are mixed in predetermined amounts and weighed, and the mixture is heated to 800~
1,000 times zero for 2 to 8 hours.

仮焼物を粉砕後、成形し、次いで成形物を１，１３０〜
１．３００℃で暁結して磁器を得る。この磁器に所定の
方法で分極処理を施し、圧電特性を持たせる。実施例 出発原料粉末としてＮａ２Ｃ０３，Ｌｉ２Ｃ０３，ＮＱ
０３，Ｓｂ２０３を用いた。After pulverizing the calcined product, it is molded, and then the molded product is
1. Porcelain is obtained by crystallization at 300°C. This porcelain is polarized using a predetermined method to give it piezoelectric properties. Examples Starting raw material powders include Na2C03, Li2C03, NQ
03, Sb203 was used.

純度は炭酸塩で９９．５％以上ＮＱ０３，Ｓら０３は共
に９９．５％以上である。これらの原料を所定量、秤量
し、エタノールによるボールミルで湿式混合した後混合
物を乾燥した。得られた混合粉末を８５０〜９０ぴ０で
４時間空気中で仮暁した。得られた仮焼物を粉砕後厚さ
２肋、直径２５側の円板に５００〜６００ｋ９／仇の圧
力で加圧成形した。この円板試料を１１５び０ないし１
２８０℃のある温度で空気中で焼結させた。得られた磁
器の高比重、真比重を測定し、又磁器組織の観察によっ
て結晶粒子径の測定を行った。磁器組織の観察は、まず
得られた円板磁器の円面を鏡面研磨し、次にこの面を１
．０５０ｑｏで１５分間程度空気中加熱することにより
熱エッチさせ、この面を顕微鏡観察する方法によって行
った。次に圧電特性については、得られた円板磁器を厚
さ１柵、直径１８肌の円板に成形研磨し、この円板の両
面にＡｇ電極を焼きつけて１００℃のシリコンオイル中
に入れて両電極間に４なし、し腿Ｖ／側のある直流電圧
を３０分間印加して分極処理を施した。The purity of carbonate is 99.5% or more, and both NQ03 and S et al. 03 are 99.5% or more. A predetermined amount of these raw materials was weighed, wet mixed in a ball mill using ethanol, and then the mixture was dried. The obtained mixed powder was suspended in air at 850 to 90 psi for 4 hours. The obtained calcined product was pulverized and then pressure-molded into a disk with a thickness of 2 ribs and a diameter of 25 mm at a pressure of 500 to 600 k9/cm. This disk sample is 115 and 0 to 1
It was sintered in air at a temperature of 280°C. The high specific gravity and true specific gravity of the obtained porcelain were measured, and the crystal grain size was also measured by observing the porcelain structure. To observe the porcelain structure, first mirror-polish the circular surface of the obtained disc porcelain, and then polish this surface once.
．． Thermal etching was carried out by heating in the air at 0.050 qo for about 15 minutes, and the surface was observed under a microscope. Next, regarding the piezoelectric properties, the obtained disk porcelain was molded and polished into a disk with a thickness of 1 inch and a diameter of 18 mm, Ag electrodes were baked on both sides of this disk, and the disk was placed in silicone oil at 100 degrees Celsius. Polarization treatment was performed by applying a DC voltage between both electrodes for 30 minutes with a DC voltage on the thigh V/side.

分極した試料を２鰹時間放置した後、圧電特性を評価す
る為、径万向振動における電気機械結合係数（Ｋｐ）及
び周波数定数（ＮＰ：共振周波数×直径）を測定した。After the polarized sample was left for 2 hours, the electromechanical coupling coefficient (Kp) and frequency constant (NP: resonant frequency x diameter) in radial vibration were measured in order to evaluate the piezoelectric properties.

測定は１，Ｒ．Ｅ．の標準回路の方法に従い、Ｋｐの算
出は共振及び***振周波数がら算出した。さらに、誘電
率（ご／ごｏ）及び誘電体損失（ｔａｎ６）をＩＫＨｚ
の周波数で測定した。実施例を第１表に、また、比較例
を第２表にこの様にして得られた種々の組成の試料にお
ける特性を一般式（Ｎａ，〜，Ｌｉｘ）（Ｎｂ，‐ｙ，
Ｓｂｙ）０３におけるｘ，ｙの値と共に示した。第１表
において、本発明の実施例である試料番号１〜１５のも
のは、全て結晶粒子径が１０仏以下で優れた圧電特性を
有していた。Measurements were made at 1, R. E. Kp was calculated from the resonance and anti-resonance frequencies according to the standard circuit method. Furthermore, the dielectric constant (go/goo) and dielectric loss (tan6) are adjusted to IKHz.
Measured at the frequency of Examples are shown in Table 1, and comparative examples are shown in Table 2. Characteristics of samples with various compositions obtained in this way are shown using the general formula (Na, ~, Lix) (Nb, -y,
It is shown together with the x and y values in Sby)03. In Table 1, samples Nos. 1 to 15, which are examples of the present invention, all had crystal grain sizes of 10 French or less and had excellent piezoelectric properties.

これに対して、第２表に示される比較例では、ｙ＝０＜
０．００１である試料番号１６〜２２のものは、結晶粒
径が１０山を越えて１０〜２０山乃至１０〜４０仏であ
った。また、同様にｙ＝０．０５＞０．０３である試料
番号２４〜２８のものも結晶粒径が大きかった。またｘ
＝０．０２＜０．０３である試料番号１０２３のものは
、前述分極処理をしても共振−***振が観察できなく、
圧電特性を計測することができなかった。ｘ＝０．１５
＞０．１４である試料番号２２，２７のものは、Ｘ線回
折像でみて均一相ではなかった。第１ 第２ 第１表に示した試料は全て比重は真比重の９７％以上で
あり、又周波数定数は３．５５一３．７７（ＫＨｚ．ｍ
）の範囲にある。On the other hand, in the comparative example shown in Table 2, y=0<
Samples Nos. 16 to 22 with a grain size of 0.001 had crystal grain sizes of more than 10 grains, ranging from 10 to 20 grains to 10 to 40 grains. Similarly, samples Nos. 24 to 28 where y=0.05>0.03 also had large crystal grain sizes. Also x
For sample number 1023 where =0.02<0.03, resonance-antiresonance could not be observed even after the above polarization treatment.
It was not possible to measure piezoelectric properties. x=0.15
Sample numbers 22 and 27 with >0.14 did not have a homogeneous phase as seen in the X-ray diffraction images. 1 2 All the samples shown in Table 1 have a specific gravity of 97% or more of the true specific gravity, and a frequency constant of 3.55-3.77 (KHz.m
) is within the range.

第１表及び上記の特性から明らかな様に、本発明による
圧電性磁器は結晶子径が小さく均一であり、さらに大き
い電気機械結合係数（Ｋｐ）を有し、誘電率（ごノごｏ
）が小さいという特徴を有し、さらに周波数定数が大き
いので高周波での電気機械変換素子用の圧電性磁器とし
て好適である。As is clear from Table 1 and the above characteristics, the piezoelectric porcelain according to the present invention has a small and uniform crystallite diameter, a large electromechanical coupling coefficient (Kp), and a dielectric constant (Kp).
) and has a large frequency constant, making it suitable as a piezoelectric ceramic for electromechanical transducers at high frequencies.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明になる圧電性磁器の組成範囲を示す。 １〜１５：実施例、１６〜２７：比較例。 愛／函 FIG. 1 shows the composition range of the piezoelectric ceramic according to the present invention. 1 to 15: Examples, 16 to 27: Comparative examples. love/box

Claims (1)

【特許請求の範囲】 １ （Ｎａ＿１＿−＿ｘ，Ｌｉ＿ｘ）Ｎｂ＿１＿−＿ｙ
，Ｓｂ＿ｙＯ＿３で示される組成で構成され、０．０３
≦Ｘ≦０．１４，０．００１≦ｙ≦０．０３の範囲内の
組成を有する圧電性磁器。 ２ ｘ，ｙが、 ０．０３≦ｘ≦０．１０で０．００２≦ｙ≦０．０１
，０．１０≦ｘ≦０．１４で０．００２≦ｙ≦０．０３
の範囲の組成を有することを特徴とする特許請求の範囲
第１項記載の圧電性磁器。[Claims] 1 (Na_1_-_x, Li_x) Nb_1_-_y
, Sb_yO_3, 0.03
Piezoelectric porcelain having a composition within the range of ≦X≦0.14, 0.001≦y≦0.03. 2 x, y are 0.03≦x≦0.10 and 0.002≦y≦0.01
, 0.10≦x≦0.14 and 0.002≦y≦0.03
The piezoelectric porcelain according to claim 1, having a composition in the range of .