Pb(Sc_(1/2)Ta_(1/2))O_(3)铁电陶瓷的制备及热膨胀性能研究

Preparation and thermal expansion properties of Pb(Sc_(1/2)Ta_(1/2))O_(3) ferroelectric ceramics

由于Pb(Sc_(1/2)Ta_(1/2))O_(3)弛豫铁电陶瓷较高的烧结温度易导致Pb挥发,固相法制备难。首先,采用钨锰铁矿法合成纯相结构的ScTaO4和Pb(Sc_(1/2)Ta_(1/2))O_(3)粉体。其次,分别采用直接埋烧法、PbO过量法、两步烧结法对陶瓷的制备工艺进行探索。最后,对陶瓷的热膨胀性能进行分析。结果表明:直接埋烧法和PbO过量法产生了大量焦绿石相和钽氧化物,合成的主晶相较少。两步烧结法有效抑制了Pb的挥发,制备的陶瓷以立方钙钛矿相为主。随温度升高,热应变呈现升高趋势,在-150~150℃内,其值为正。热膨胀率与温度的关系图为V型,约为-30℃时热膨胀系数最低,其值为负。

The preparation of Pb(Sc_(1/2)Ta_(1/2))O_(3) relaxor ferroelectric ceramics by solid-state reaction method has been a difficult problem due to the high sintering temperature easily leads to volatilization of Pb.Firstly,the pure phase ScTaO4 and Pb(Sc_(1/2)Ta_(1/2))O_(3) powders were synthesized by the wolframite precursor route.Secondly,during the sintering process,the direct burying sintering method,PbO excess method and two-step sintering method were used to explore the preparation process of ceramics.Finally,the thermal expansion properties of the ceramics were analyzed.The results reveal that the direct burying sintering and PbO excess methods lead to the production of a large number of pyrochlore phases and tantalum oxides,with relatively few synthesized main crystals.The two-step sintering method effectively inhibites the volatilization of Pb,and the prepared ceramics are mainly cubic perovskite phase.With the increase of temperature,the thermal strain shows an increasing trend,and its value is positive in the temperature range of-150℃to 150℃.The relation graph of thermal expansion rate with temperature is V-shaped,and the coefficient of thermal expansion is the lowest at-30℃,and its value is negative.