水热前驱体法低温合成Pb(Mg1/2W1/2)O3-PbTiO3

目的制备纯钙钛矿相的Pb(Mg1/2W1/2)O3-PbTiO3(PMW-PT)陶瓷。方法以Mg(Ac)2·4H2O,Pb(Ac)2.4H2O,Na2WO4·3H2O和Ti(OC4H9)4为原料,NaOH调节反应体系的pH值9～13,在200℃下12 h水热合成PMW-PT前驱体,通过煅烧该前驱体制备纯钙钛矿相的PMW-PT粉体。通过XRD分析研究水热处理温度、反应时间、溶液pH值以及煅烧温度对PMW-PT相和中间产物Pb2TiWO7相生成过程的影响。结果水热处理的粉体转化为钙钛矿相PMW-PT最佳煅烧温度为800℃,压片后1 000℃烧结2 h制备的PMW-PT陶瓷,介电常数为12 067(1 kHz)。结论与固相法和半化学法相比,这种方法制备的钙钛矿PMW-PT粉体在较低的温度下生成,而且陶瓷的介电常数较高。

Low-temperature synthesis of perovskite Pb(Mg1/2W1/2)O3-PbTiO3 via a hydrothermally derived precursor

Aim To prepare pure perovskite phase Pb(Mg1/2W1/2)O3-PbTiO3 (PMW-PT) ceramics. Methods Powders of PMW-PT precursor were synthesized at temperatures as low as 200 ℃ by means of hydrothermal synthesis using Mg(Ac)2·4H2O, Pb(Ac)2·4H2O, Na2WO4·3H2O, and Ti(OC4H9)4 as starting materials. NaOH was used to adjust the pH of the reaction system to values between 9 and 13. Pure-phase perovskite PMW-PT powders were prepared by calcining the hydrothermally derived compounds. By X-ray diffraction analysis, the influence of the hydrothermal temperature, reaction time, solution pH, and calcination temperature on the formation of the PMW-PT phase and of an intermediate Pb2TiWO7 phase were investigated. Results The hydrothermally derived powders transformed optimally into perovskite PMW-PT after calcining at 800 ℃. Compressed ceramics of PMW-PT produced by sintering at 1 000 ℃ for 2 h exhibited a dielectric constant of 12 067 at a frequency of 1 kHz. Conclusion Compared with solid-state and semichemical methord, perovskite PMW-PT powders are formed at a lower temperature in this synthetic rote and the dielectric constant of the ceramic is higher.