Piezoceramic material

Abstract

FIELD: piezoceramic materials.SUBSTANCE: invention relates to the field of ferroelectric-rigid piezoceramic materials based on lead zirconate titanate for ultrasonic devices, including angular velocity sensors operating under strong electrical and mechanical influences. These piezoceramic materials are characterized by low dielectric losses in weak and strong fields, high mechanical quality factor and relatively high electromechanical coupling coefficients. Piezoelectric ceramic material based on lead titanate, obtained from a batch comprising components in the following quantities, wt.%: Pb3O4 66.2; SrCO3 2; ZrO2 17.5; TiO2 10.4; MnO2 0.6; Sb2O3 1.5; ZnO 0.4; Nb2O5 1.4; CeO2 0.033 over 100%.EFFECT: increasing the values of the electromechanical quality factor to Qm= 2717 while maintaining high values of the electromechanical coupling coefficient of the planar oscillation mode Kp = 0.267-0.234.1 cl, 4 tbl

Description

[0001] The invention relates to the field of ferroelectric-rigid piezoceramic materials based on lead zirconate titanate for ultrasonic devices, including angular velocity sensors operating under strong electrical and mechanical influences.

[0002] Such materials of the lead zirconate titanate (PZT) system include: PIC 181, PIC 141, PIC 241, PIC 300 (Germany) [Catalog of Physik Instrumente (PI) GmbH & Co. KG, Germany], PZT-38, PZT-39 (Russia) [Catalog of piezoceramic materials and elements of JSC Research Institute ELPA, Russia] (2), etc.

[0003] One of the closest is “Piezoceramic material” patent RU 2 219 143 C2, which has an electromechanical quality factor value Q m =1000, piezoceramic material according to the patent analogue, including oxides of lead, zirconium, titanium, manganese, zinc and niobium, mass %:

[0004] PbO 68.50-68.70

[0005] ZrO215.70-16.70

[0006] TiO210.20-10.70

[0007] MnO 0.30-0.35

[0008] ZnO 0.70-0.90

[0009] Nb2O53.50-4.20

[0010] subjected to solid-phase synthesis and subsequent sintering, wherein the solid-phase synthesis is carried out in two stages, with the second stage of solid-phase synthesis being carried out at 1170 K, and sintering being carried out in an atmosphere of lead oxide vapor.

[0011] The disadvantage of the specified piezoceramic material is the low values ​​of electromechanical quality factor.

[0012] The technical result of the invention consists in increasing the values ​​of electromechanical quality factor to Q m =2717 while maintaining high values ​​of the electromechanical coupling coefficient of the planar oscillation mode K p =0.267-0.234. These piezoceramic materials are characterized by low dielectric losses in weak and strong fields, high mechanical quality factor and relatively high electromechanical coupling coefficients.

[0013] Piezoelectric ceramic material based on lead zirconate titanate contains, mass % (1 table).

[0014] Table 1. Composition of the charge

[0015] Component Pb3O4 SrCO3 ZrO2 TiO2 MnO2 Sb2O3 ZnO Nb2O5 Purity 0,98 0,98 0,98 0,99 0,75 0,95 0,99 0,99 Mass. % 66,2 2 17,5 10,4 0,6 1,5 0,4 1,4

[0016] Cerium oxide CeO2 was added as a separate additive at a rate of 0.01 g per 30 g batch (purity 0.98). The composition of the material corresponds to the formula:

[0017] 0.9Pb 0.95 Sr 0.05 (Zr 0.52 Ti 0.48 )O3-0.05Pb(Zn 1 / 3 Nb 2 / 3 )O3-0.05Pb(Mn 1 / 3 Sb 2 / 3 )O3+CeO2.

[0018] Example: To obtain 30 g of high-quality ferroelectric material, a batch of the following components is prepared.

[0019] Table 2. Composition of the batch for obtaining 30 g of material

[0020] Component Pb3O4 SrCO3 ZrO2 TiO2 MnO2 Sb2O3 ZnO Nb2O5 CeO2 Weight, g 19,884 0,605 5,254 3,111 0,172 0,457 0,121 0,396 0.01

[0021] The ceramics were produced using standard two-stage ceramic technology.

[0022] The mixture was mixed and ground in a planetary ball mill.

[0023] The batch components were placed in a zirconia beaker containing ceramic zirconia balls. 99% isopropyl alcohol was then added to the beaker until the ceramic zirconia balls reached the same level. Mixing and grinding continued for 2 hours.

[0024] Then the mixed components of the batch were dried, followed by separation of the ceramic balls by sifting the mixture through a nylon sieve with a mesh size of ~ 100 µm.

[0025] The dried batch was pressed into a cylinder using a manual hydraulic press and a collapsible steel mold with a 36 mm punch diameter at a pressure of ~51 MPa. The pressed material was placed on an alumina substrate. To compensate for lead loss during heating, a molded cylinder of a mixture of lead oxide (Pb3O4) and zirconium oxide (ZrO2) in a ratio of 85% to 15%, respectively, was placed on top of the pressed batch cylinder. The corundum substrate containing the molded materials was covered with a corundum crucible and then placed in a muffle furnace to synthesize the high-quality ceramic material.

[0026] The synthesis stage was carried out in a high-temperature muffle furnace at a temperature of 800 °C for four hours, followed by cooling with the furnace in air.

[0027] After synthesis, the obtained material was ground in a planetary ball mill in an isopropyl alcohol medium for two hours, then the powder was dried and sieved through a nylon sieve with a mesh size of 100 μm. ~5 wt.% of a 3% polyvinyl alcohol solution was added to the dried powder, followed by grinding in a corundum mortar, drying, and sifting through a nylon sieve with a mesh size of 100 μm. The resulting powder was molded in a steel mold with a punch diameter of 12 mm at a pressure of ~130 MPa with a holding time of 3 minutes. The resulting samples were placed on a corundum substrate in a backfill of Al2O3 with a pressed tablet of a mixture of Pb3O4 and ZrO2 in a ratio of 85%:15%. Next, the sintering blank was covered with an Al2O3 crucible and placed in a muffle furnace for the ceramic sample sintering stage. Sintering of the samples was performed in air according to the following program:

[0028] - Heating from room temperature to 100°C at a rate of 100°C per hour;

[0029] - Exposure 1 hour;

[0030] - Heating from 100°C to 180°C at a rate of 90°C per hour;

[0031] - Exposure 1 hour;

[0032] - Heating from 180°C to 480°C at a speed of 350°C;

[0033] - Exposure 1 hour;

[0034] - Heating from 480 C to 1100-1200 °C at a rate of 350 °C per hour;

[0035] - Exposure 3.5 hours;

[0036] - Cooling with a muffle furnace.

[0037] The fired samples were cleaned and polished. Next, to create electrodes, conductive silver paste PP-17 (Elma-Pastes LLC) was applied to the flat surfaces of the samples, followed by firing in a muffle furnace at 660°C for 10 minutes.

[0038] Polarization of the samples was carried out using a universal breakdown unit UPU-10 in a silicone oil environment at a temperature of 150 °C in a constant electric field of 4 kV for four hours.

[0039] In accordance with GOST 12370-72, the electrophysical characteristics, the coefficient of electromechanical coupling of the planar oscillation mode (K p ), density ρ, permittivity ε, resonator resistance at resonant frequency R r , piezomodule d 31 , mechanical quality factor Q m The measured parameters of piezoelectric samples obtained at different sintering temperatures are given in Table 3.

[0040] Table 3. Parameters of the obtained samples at different sintering temperatures

[0041] Sintering temperature, °C Kp ρ, g / cm3 ε (at 20 °C) Rr, Ohm d31, pC / N Qm 1100 0.26 8.2 705 94.8 43 104 1150 0.267 7.7 1064 4.8 54 1491 1200 0.234 8.05 884 3.7 41 2717 1250 0.07 6.45 190 1876 5 171

[0042] Table 4. Comparative electrophysical parameters of analog materials and the optimal composition of the declared piezoelectric ceramic material

[0043] Piezoelectric material brand Kp ρ, g / cm3 ε (at 20 °C) Qm PIC 181 (Germany) 0,56 7,8 1200 2000 PIC 141 (Germany) 0,55 7,8 1250 1500 PIC 241 (Germany) 0,5 7,8 1650 1200 PIC 300 (Germany) 0,48 7,8 1050 1400 Russian Federation Patent RU 2 219 143 C2 0,56 7,2 1300 1000 Suggested material 0.234 8.05 884 2717

[0044] The technical result consists in increasing the values ​​of electromechanical quality factor to Q m =2717, due to a certain ratio of the composition components, an additional addition of cerium oxide and certain modes of obtaining the piezoceramic material, synthesis at 800 °C, and final sintering at 1200 °C in an atmosphere of lead oxide vapor.