RU2498960C2 - Piezoelectric ceramic material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to piezoelectric ceramic materials based on sodium niobate and can be used in making low-frequency receivers - hydrophones, microphones, hydro receivers, as well as in making low-frequency electromechanical transducers, which excite metallic resonators with high sound speed. The piezoelectric ceramic material contains sodium, potassium, cadmium and niobium oxides, with the following ratio of components, wt %: Na₂O 8.75-9.72, K₂O 5.31-5.38, CdO 9.15-10.88, Nb₂O₅ 75.05-75.77. The material is produced using conventional ceramic processing.

EFFECT: material has high relative permittivity of polarised samples, sound speed and mechanical Q-factor.

3 ex, 5 tbl

Description

, (1300÷2000), скорости звука, $$V_1^E$$

, (4.5÷5.5 км/с), механической добротности, Q_m, (>1000).The invention relates to piezoelectric ceramic materials based on sodium niobate and can be used to create low-frequency receivers - hydrophones, microphones, geophones, and also to create low-frequency electromechanical converters that excite metal resonators with a high speed of sound. For these applications, the material must have high values of relative permittivity, $${\epsilon }_{33}^T/{\epsilon }_0$$

, (1300 ÷ 2000), sound velocity, $$V_{\mathrm{one}}^E$$

, (4.5 ÷ 5.5 km / s), mechanical Q factor, Q _m , (> 1000).

, $$V_1^E=3.15÷4.0$$

км/с, Q_m=125÷145 (Е.Г. Фесенко, O.H. Разумовская, А.Я. Данцигер, Л.А. Резниченко. Пьезоэлектрический керамический материал // Авторское свидетельство №601260 от 14.12.1977, по заявке 2421001 от 18.11.1976 (приоритет), опубликовано 05.04.1978. Бюллетень №13). Для указанных применений материал имеет недостаточно высокие значения Q_m. Кроме того, материал в своем составе содержит токсичный элемент Pb.Known piezoelectric ceramic material based on sodium niobate, including Na ₂ O, Li ₂ O, Nb ₂ O ₅ , PbO, TiO ₂ , ZrO ₂ . Material has $${\epsilon }_{33}^T/{\epsilon }_0=2000÷2300$$

, $$V_{\mathrm{one}}^E=3.15÷4.0$$

km / s, Q _m = 125 ÷ 145 (EG Fesenko, OH Razumovskaya, A.Ya. Danziger, L.A. Reznichenko. Piezoelectric ceramic material // Author's certificate No. 601260 of 12/14/1977, according to application 2421001 of 11/18/1976 (priority), published 04/05/1978, Bulletin No. 13). For these applications, the material has not high enough values of Q _m . In addition, the material in its composition contains the toxic element Pb.

. Для указанных применений материал имеет заниженное значение $${\epsilon }_{33}^T/{\epsilon }_0$$

(Е.Г. Фесенко, О.Н. Разумовская, А.Я. Данцигер, Л.А. Резниченко, А.Н. Клевцов. Пьезоэлектрический керамический материал. // Авторское свидетельство №619470 от 21.04.1978, по заявке 2421002 от 18.11.1976 (приоритет), опубликовано 15.08.1978. Бюллетень №30).Known piezoelectric ceramic material based on sodium niobate, including Na ₂ O, Li ₂ O, Nb ₂ O ₅ , CdO. Material has $${\epsilon }_{33}^T/{\epsilon }_0=1070÷1240$$

. For these applications, the material is undervalued $${\epsilon }_{33}^T/{\epsilon }_0$$

(EG Fesenko, O.N. Razumovskaya, A.Ya. Danziger, L.A. Reznichenko, A.N. Klevtsov. Piezoelectric ceramic material. // Copyright certificate No. 619470 of 04/21/1978, according to application 2421002 of 11/18/1976 (priority), published 08/15/1978, Bulletin No. 30).

, $$V_1^E=\left(4.89÷5.15\right)$$

км/с, Q_m=70÷100. Для указанных применений материал имеет недостаточно высокие значения $${\epsilon }_{33}^T/{\epsilon }_0$$

и Q_m (Е.Г. Фесенко, Л.А. Резниченко, О.Н. Разумовская, Л.С. Иванова, Л.А. Шилкина, С.И. Дудкина. Пьезоэлектрический керамический материал. // Авторское свидетельство №1425181 от 22.05.1988, по заявке 4215651 от 26.03.1987 (приоритет), опубликовано 23.09.1988. Бюллетень №35).Known piezoelectric ceramic material based on sodium niobate, including Na ₂ O, Li ₂ O, Nb ₂ O ₅ , PbO. Material has $${\epsilon }_{33}^T/{\epsilon }_0=330÷1080$$

, $$V_{\mathrm{one}}^E=\left(4.89÷5.15\right)$$

km / s, Q _m = 70 ÷ 100. For these applications, the material is not high enough $${\epsilon }_{33}^T/{\epsilon }_0$$

and Q _m (E.G. Fesenko, L.A. Reznichenko, O.N. Razumovskaya, L.S. Ivanova, L.A. Shilkina, S.I. Dudkina. Piezoelectric ceramic material. // Copyright certificate No. 1425181 dated 05/22/1988, according to the application 4215651 of 03/26/1987 (priority), published on 09/23/1988, Bulletin No. 35).

, $$V_1^E=\left(5.50÷5.65\right)$$

км/с, Q_m=300÷632 (Е.Г. Фесенко, Л.А. Резниченко, О.Н. Разумовская, Л.С. Иванова, Н.В. Дергунова. Пьезоэлектрический керамический материал. // Авторское свидетельство №1294791 от 8.11.1986, по заявке 3967500 от 14.10.1985 (приоритет), опубликовано 07.03.1987. Бюллетень №9) (прототип). Для указанных применений материал имеет недостаточно высокое значение Q_m.The closest claimed material in technical essence and the achieved result is a piezoelectric ceramic material based on sodium niobate, including Na ₂ O, Li ₂ O, Nb ₂ O ₅ , Sb ₂ O ₅ . Material has $${\epsilon }_{33}^T/{\epsilon }_0=1510÷2700$$

, $$V_{\mathrm{one}}^E=\left(5.50÷5.65\right)$$

km / s, Q _m = 300 ÷ 632 (E.G. Fesenko, L.A. Reznichenko, O.N. Razumovskaya, L.S. Ivanova, N.V. Dergunova. Piezoelectric ceramic material. // Copyright certificate No. 1294791 dated 11/08/1986, according to the application 3967500 from 10/14/1985 (priority), published on 03/07/1987, Bulletin No. 9) (prototype). For these applications, the material has a low Q _m value.

и $$V_1^E$$

.The objective of the invention is to increase Q _m (to values> 1000) while maintaining high values $${\epsilon }_{33}^T/{\epsilon }_0$$

and $$V_{\mathrm{one}}^E$$

.

This result is achieved in that the piezoelectric ceramic material based on sodium niobate, including Na ₂ O, Nb ₂ O ₅ , additionally contains K ₂ O and CdO in the following ratio of components, in wt.%:

Na ₂ O = 8.75 ÷ 9.72, K ₂ O = 5.31 ÷ 5.38, CdO = 9.15 ÷ 10.88, Nb ₂ O ₅ = 75.05 ÷ 75.77

The composition of the material corresponds to the formula (Na _a K _b Cd _c ) NbO ₃ , where

a = (0.5 ÷ 0.55 mol%), b = (0.2 mol%), c = (0.125 ÷ 0.15 mol%).

a + b + 2c = 100%.

1. Example 1 of the manufacture of a piezoelectric ceramic material (hereinafter, the numbering of examples corresponds to table1).

The material was manufactured by conventional ceramic technology as follows. Hydrocarbonates, carbonates and oxides of the following qualifications were used as initial reagents: NaHCO ₃ - “chda”, KHCO ₃ - “h”, Nb ₂ O ₅ - “NbO-PT”, CdO - “hch”.

The synthesis was carried out by a single firing of mixtures of raw components: NaHCO ₃ , KHCO ₃ , Nb ₂ O ₅ , CdO, taken in quantities (mass%, in the case of NaHCO ₃ , KHCO ₃ in terms of the corresponding oxides): Na ₂ O = 6.82, K ₂ O = 5.22, Nb ₂ O ₅ = 73.63, CdO = 14.33; with intermediate grinding of the synthesized product. The firing temperatures in the synthesis of T _synth. 1 = 1220 K, T _synt . ₂ = 1240 K, the duration of isothermal _aging τ _synt. 1 = 5 hours, τ _synt . ₂ = 10 hours. Sintering of samples in the form of columns ⌀12 mm, height 15 ÷ 18 mm was carried out at T _sp. = 1460 K, the duration of the isothermal hold _cn τ = 1.5 h. Metallization (applying electrodes) made by coating the flat surface of the pre-ground portion to a thickness of 1 mm samples silver-containing paste and its subsequent brazing at a temperature T _vzhig. = 1070 K for 0.5 h. Samples were polarized in a polyethylene siloxane liquid at a temperature of 420 K for 15 min. in a constant electric field of 3.6 kV / cm.

2. Example 4 of the manufacture of a piezoelectric ceramic material.

The material was manufactured by conventional ceramic technology as follows. Hydrocarbonates, carbonates and oxides of the following qualifications were used as initial reagents: NaHCO ₃ - “chda”, KHCO ₃ - “h”, Nb ₂ O ₅ - “NbO-PT”, CdO - “hch”.

The synthesis was carried out by a single firing of mixtures of raw components: NaHCO ₃ , KHCO ₃ , Nb ₂ O ₅ , CdO, taken in quantities (mass%, in the case of NaHCO ₃ , KHCO ₃ in terms of the corresponding oxides): Na ₂ O = 9.23, K ₂ O = 5.34, Nb ₂ O ₅ = 75.42, CdO = 10.01; with intermediate grinding of the synthesized product. The firing temperatures in the synthesis of T _synth. 1 = 1220 K, T _synt . ₂ = 1240 K, the duration of isothermal _aging τ _synt. 1 = 5 hours, τ _synt . ₂ = 10 hours. Sintering of samples in the form of columns ⌀12 mm, height 15 ÷ 18 mm was carried out at T _sp. = 1460 K, the duration of the isothermal hold _cn τ = 1.5 h. Metallization (applying electrodes) made by coating the flat surface of the pre-ground portion to a thickness of 1 mm samples silver-containing paste and its subsequent brazing at a temperature T _vzhig. = 1070 K for 0.5 h. Samples were polarized in a polyethylene siloxane liquid at a temperature of 420 K for 15 min. in a constant electric field with a voltage of 3.0 kV / cm.

3. Example 7 of the manufacture of a piezoelectric ceramic material.

The material was manufactured by conventional ceramic technology as follows. Hydrocarbonates, carbonates and oxides of the following qualifications were used as initial reagents: NaHCO ₃ - “chda”, KHCO ₃ - “h”, Nb ₂ O ₅ - “NbO-PT”, CdO - “hch”.

The synthesis was carried out by a single firing of mixtures of raw components: NaHCO ₃ , KHCO ₃ , Nb ₂ O ₅ , CdO, taken in quantities (mass%, in the case of NaHCO ₃ , KHCO ₃ in terms of the corresponding oxides): Na ₂ O = 11.65, K ₂ O = 5.48, Nb ₂ O ₅ = 77.18, CdO = 5.69; with intermediate grinding of the synthesized product. The firing temperatures in the synthesis of T _synth. 1 = 1220 K, T _synt . ₂ = 1240 K, the duration of isothermal _aging τ _synt. 1 = 5 hours, τ _synt . ₂ = 10 hours. Sintering of samples in the form of columns ⌀12 mm, height 15 ÷ 18 mm was carried out at T _sp. = 1410 K, the duration of the isothermal hold _cn τ = 1.5 h. Metallization (applying electrodes) made by coating the flat surface of the pre-ground portion to a thickness of 1 mm samples silver-containing paste and its subsequent brazing at a temperature T _vzhig. = 1070 K for 0.5 h. Samples were polarized in a polyethylene siloxane liquid at a temperature of 420 K for 15 min. in a constant electric field of 3.5 kV / cm.

(ε₀ - диэлектрическая постоянная) образцов, механическая добротность, Q_m, скорость звука, $$V_1^E$$

.Electrical characteristics were determined in accordance with OST 11.0444-87. The relative permittivities of polarized samples were measured, $${\epsilon }_{33}^T/{\epsilon }_0$$

(ε ₀ - dielectric constant) of samples, mechanical quality factor, Q _m , speed of sound, $$V_{\mathrm{one}}^E$$

.

Figure 1, where table 1 is shown, shows the main characteristics of the material depending on the composition, and figure 2, which shows table 2, shows the main electrophysical characteristics of the optimal compositions of the proposed material.

The obtained experimental data (Fig. 1, Table 1, examples No. 3-5) show that the piezoelectric ceramic material of the proposed composition has optimal, from the point of view of the technical problem being solved, characteristics in the indicated range of concentration values.

при сохранении $$V_1^E$$

.Thus, the positive effect of the proposed material is due to its qualitative and quantitative composition, which is also confirmed by examples No. 1, 2, 6, 7, demonstrating the deterioration of properties outside the proposed range of concentrations of the components. Violation of these limits leads, as can be seen from table 1 (figure 1), to reduce Q _m $${\epsilon }_{33}^T/{\epsilon }_0$$

when saving $$V_{\mathrm{one}}^E$$

.

The proposed piezoelectric ceramic material is obtained by conventional ceramic technology without the use of an expensive method of hot pressing (as in the prototype). This greatly simplifies and reduces the cost of the process.

и $$V_1^E$$

(4.56÷4.74) км/с. Эффект повышения Q_m достигается по существу дополнительным введением в материал, включающий Na₂O и Nb₂O₅, оксидов калия и кадмия.The data shown in figures 1, 2 (table 1, 2) confirm the advantages of a piezoelectric ceramic material compared with the prototype material, namely, an increase in Q _m (one and a half times) to values of 1000 ÷ 1060 while maintaining high $${\epsilon }_{33}^T/{\epsilon }_0=1356÷2024$$

and $$V_{\mathrm{one}}^E$$

(4.56 ÷ 4.74) km / s. The effect of increasing Q _{m is} achieved essentially by the additional introduction of potassium and cadmium oxides into the material, including Na ₂ O and Nb ₂ O ₅ .

, предлагаемого керамического материала (>2000) определяет его основное назначение - низкочастотные приемные устройства - гидрофоны, микрофоны, сейсмоприемники, а также для создания низкочастотных электромеханических преобразователей, возбуждающих металлические резонаторы с высокой скоростью звука. Это следует, прежде всего, из того, что твердые растворы (TP) на основе ниобатов щелочных металлов (НЩМ) могут использоваться в качестве резонансных элементов пьезоэлектрических преобразователей в высокочастотных (ВЧ) (3.0÷30.0 МГц) и (ОВЧ) и (30.0÷300.0) МГц, среднечастотном (СЧ) (0.3÷3.0) МГц; низкочастотном (НЧ) (30.0÷300.0) кГц) и ультранизкочастотном (ОНЧ) (<30.0 кГц) диапазонах. Классификация электромагнитных волн по частотным диапазонам представлена в (Носов Ю.Н., Кукаев А.А. Энциклопедия отечественных антенн. / Справочное издание. М., 2001. С.49): высокие частоты (ВЧ) - (3.0÷30.0) МГц; очень высокие частоты (ОНЧ) - (30.0÷300.0) МГц; средние частоты (СЧ) - (300.0÷3000.0) кГц; низкие частоты (НЧ) - (30.0÷300.0) кГц; очень низкие частоты (ОНЧ) - (3.0÷30.0) кГц.High relative permittivity $${\epsilon }_{33}^T/{\epsilon }_0$$

The proposed ceramic material (> 2000) determines its main purpose - low-frequency receivers - hydrophones, microphones, geophones, and also for creating low-frequency electromechanical transducers that excite metal resonators with a high speed of sound. This follows, first of all, from the fact that solid solutions (TP) based on alkali metal niobates (NSM) can be used as resonant elements of piezoelectric transducers in high-frequency (HF) (3.0 ÷ 30.0 MHz) and (VHF) and (30.0 ÷ 300.0) MHz, mid-frequency (MF) (0.3 ÷ 3.0) MHz; low-frequency (LF) (30.0 ÷ 300.0) kHz) and ultra-low-frequency (VLF) (<30.0 kHz) ranges. Classification of electromagnetic waves by frequency ranges is presented in (Nosov Yu.N., Kukaev A.A. Encyclopedia of domestic antennas. / Reference edition. M., 2001. P.49): high frequencies (HF) - (3.0 ÷ 30.0) MHz ; very high frequencies (VLF) - (30.0 ÷ 300.0) MHz; middle frequencies (MF) - (300.0 ÷ 3000.0) kHz; low frequencies (LF) - (30.0 ÷ 300.0) kHz; very low frequencies (VLF) - (3.0 ÷ 30.0) kHz.

, где k - коэффициент, зависящий от размеров элементов, ε₀=8.85·10^-12 Ф - диэлектрическая проницаемость вакуума; при k=1, $${\epsilon }_{33}^T/{\epsilon }_0=C$$

.Provided that the converter is matched to the load (R _i = R _n ) (usually the output impedance R _n ~ 50 Ohms for high and medium frequencies and 1000 Ohms for low frequencies commonly used in commercial electronic equipment), using the formula for the capacitance of the converter: R _i = 1 / ωC, where R _i is the capacitance of the converter, Ohm; ω is the circular frequency, Hz; C is the capacitance, Ф, it is possible to approximately estimate the intervals of the capacitance values C = 1 / 2πfR _i for the indicated frequency ranges, and, consequently, the relative dielectric constant of polarized elements, $${\epsilon }_{33}^T/{\epsilon }_0=k\cdot C$$

where k is a coefficient depending on the size of the elements, ε ₀ = 8.85 · 10 ^-12 F is the dielectric constant of the vacuum; for k = 1, $${\epsilon }_{33}^T/{\epsilon }_0=C$$

.

, реализуемые на объемных керамических образцах.Fig 3-5 (table 3-5) shows the values of the relative dielectric constant $${\epsilon }_{33}^T/{\epsilon }_0$$

sold on bulk ceramic samples.

полезны и для снижения габаритов, что важно при разработке гидроакустических устройств. Высокие Q_m материалов определяют высокую эффективность электромеханических преобразователей на их основе (т.е. низкие потери на внутреннее трение, 1/Q_m) (А.Я. Данцигер, О.Н. Разумовская, Л.А. Резниченко, С.И. Дудкина. Высокоэффективные пьезокерамические материалы. Оптимизация поиска. / Ростов-на-Дону: Пайк. 1995. 92 с.).Thus, at higher frequencies, sufficiently high capacitance values (relative permittivity) are needed to reduce the resistance of the converter, which improves its coordination with the load. High values $${\epsilon }_{33}^T/{\epsilon }_0$$

useful for downsizing, which is important when developing sonar devices. High Q _m materials determine the high efficiency of electromechanical converters based on them (i.e., low losses due to internal friction, 1 / Q _m ) (A.Ya. Danziger, O.N. Dudkina. Highly effective piezoceramic materials. Search optimization. / Rostov-on-Don: Pike. 1995. 92 p.).

From the above it follows that the technical result of the invention is achieved by a new set of essential features, both newly introduced and known, therefore, the inventive piezoelectric ceramic material meets the patentability criterion of "inventive step".

The proposed piezoelectric ceramic material provides the result, does not cause difficulties in manufacturing, offers the use of basic (affordable and cheap) materials (reagents) and standard equipment that corresponds to the industrial method of conventional ceramic technology (without using the expensive, expensive method of hot pressing (K. Okazaki. Technology ceramic dielectrics. / Transl. from Japanese. M .: Energy. 1976. 336 p.)), which indicates the conformity of the claimed technical solution to the criterion identity "industrial applicability".

Claims (1)

Piezoelectric ceramic material based on sodium niobate, including Na ₂ O, Nb ₂ O ₅ , characterized in that it further contains K ₂ O and CdO in the following ratio of components, wt.%:
Na ₂ O 8.75 ÷ 9.72 K ₂ O 5.31 ÷ 5.38 Cdo 9.15 ÷ 10.88 Nb ₂ O ₅ 75.05 ÷ 75.77

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