SU1203078A1 - Piezoelectric ceramic material - Google Patents

Description

The invention relates to a piezo technique and can be used as a material in the design of piezoceramic devices, in particular, acoustic transducers with a wide operating temperature range and minimal amplitudes of parasitic oscillation modes, due to the high anisotropy of the piezoelectric properties (d33 / d3iS: 10, K ( Cr; 7), low mechanical Q of Qf (r; 30) at high values of 80. 10 - C / n.

In order for the electromechanical converter to work efficiently, the material from which it is made must, along with high values of the electrical coupling coefficient, the basic thickness of the Koban mode K and the piezomodule d33, have low values of the Electromechanical coupling coefficient of the radial oscillations, Kp and piezomodule, have a low mechanical quality factor and high Curie temperature (TC).

The aim of the invention is to increase the anisotropy of the piezoelectric properties and the electromechanical coupling coefficient.

The introduction of NbaOg into the PbNbjiO system — K2.Nbj, 06 leads to an increase in the sintering stage of crystallite sizes to 100–200 µm, which is one of the necessary conditions for achieving a high level of piezoelectric parameters.

The synthesis of the composition of the ceramic material is carried out using the following reactives as a raw material: PbO (or PbCOj) ch.a., NbiOg Nbo-Fri, chem.ch.

The material is synthesized by solid-phase reactions. At the first stage, methane biobates (PbNbjO) and potassium (KSeO3) are obtained.

Lead methaniobate is synthesized from the PHO (or PbCOj) mixture: Nbj.O S - 1: 1,

wet blended on a vibratory mill. The temperature of the synthesis is 950-1000 s, the duration is 3 hours. The specs are ground in a ball mill. To obtain KNbOj, the components are mixed in a vibromeliopia-dry process and the gaicht is fired twice at 850 ° C (10 hours) and (5 hours). The material is synthesized from a mixture of PbNbjOg, KNb03 and once baked at 1100 C for A h. The control over the completeness of the reaction and the structure of the product formed is carried out with a phase analysis (XRP).

Sintering was carried out by hot pressing at temperatures of TSPEC. 1250 + 20 C, pressure

2-10 Pa, holding time 40 min. OE raszg have the form of a disk with a diameter of 10 mm and a thickness of 0.5 mm. Electrodes are applied by firing silver paste. Sample polarization

conducted in polyethylsiloxane. PES-5 fluids at temperatures of 140-150 С, in the field (4.0-5.5) ОО В / м.

As can be seen from the table, the material has low values of dielectric constant (215-430) and mechanical quality factor (22-39) with rather large values of the coefficient of electromechanical coupling of thickness fluctuations F-t (0.32-0.44)

12

And piezomodul d ,, (68-87) 10 C / H.

The most important advantage of this material for acoustic transducers is high

anisotropic piezoelectric

properties (Kt / Kp 4,2-7,4; d3 / d3,5,4- 10,2), as well as a high Curie temperature (Tk- 539-553 ° C). The optimal content of the parameters is possessed by a composition containing 93.96 mol.% PbNbjOe, 2.48 mol. And 3.56 mol.% Nb-jOs (composition 2 tables).

31203078

Electrophysical parameters of the compositions of the system - - NbzOs are given in the table.

195,672,521,812151,80,405,1686,922553

293,962,483,562301,10,447,48010,223550

3. 90,732,396,883401,20,356,7749,134546

487,722,319,974301,40,324,2875,439539

Compiled by O. Samokhina Editor N. Egorova Tehred S. Migunova Proofreader G. Reshetnik

Order 8383/30 Circulation 604 Subscription VNISHI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch PPP Patent, Uzhgorod, st. Project, 4

Claims (1)

PIEZOELECTRIC CERAMIC MATERIAL, including PbM _g O ₆ , KjNb ^ Ofi, characterized in that, in order to increase the anisotropy of the piezoelectric properties and the coefficient of electromechanical coupling, it additionally contains Lb _g O5 in the following ratio ponents, wt.%: РЫЬ ₂ 0б 87.72-95.67 K _g b _{y g b} 2.31-2.52 Nbj-Os 1.81-9.97