SBTV陶瓷的制备与组织性能

【作者】 孟庆昌； 吕苏华； 王文；

【机构】 哈尔滨工业大学材料学院；

【摘要】 本文采用传统固相反应法合成了Sr Bi₂Ta₂O₉（简称SBT）和V掺杂Sr Bi₂Ta₂O₉（简称SBTV）粉体,并采用模压成型方法,然后再无压烧结,制备出五种SBT系列铁电陶瓷（SBT0、SBT1、SBTV1、SBTV2、SBTV3）。V₂O₅的掺杂量分别为10mol%、20mol%和30mol%。研究表明:V₂O₅是一种的很好的助烧剂,掺杂后SBTV粉体烧结温度可降低200℃;两步烧结后纯SBT均为单一的钙钛矿相SBT;掺杂后两种成型工艺所制备的SBTV除了生成少量的第二相Bi₄(V₂O₁₁)外,也主要由钙钛矿相组成;同时五种陶瓷都发生了一定程度的择优取向。化学计量比的SBT晶粒主要为长棒状,非化学计量比的SBT有片状和棒状两种晶粒,而后者晶粒明显较大,两者都较致密;掺杂后SBTV陶瓷晶粒转换为片状。同时V掺杂后引起了晶格畸变,产生应变,SBTV陶瓷中观察到α-边界特征的90o畴。掺杂的SBTV在烧结过程中V的价态发生变化:V⁵⁺→V⁴⁺,产生了氧空位。另外,五种陶瓷的介电常数偏低;常温下,介电性能稳定。SBT1、SBTV1和SBTV2的Tc约为350℃;在相变点SBTV陶瓷的介电峰明显变宽。更多还原

【Abstract】 In this dissertation, SBT and SBTV powders were synthesized by conventional two-step solid-state reaction technique. The SBT and SBTV ceramics were fabricated by single axsis pressing and cold isostatic pressing and then sintered in air atmosphere. The content of V₂O₅ was 10mol%, 20mol% and 30mol% respectively. Sintering process, microstructure and dielectric properties of the SBT and SBTV ceramics were investigated by TG-DTA,XRD,SEM,TEM and dielectric tester. The effects of V and Bi on microstructure and dielectric properties of SBT ceramics were discussed. Studies indcated that V₂O₅ was an effective sintering aid, and V-doped lowered the sintering temperature for about 200℃. After being sintered, both SBT powders and ceramics consisted of a single layered perovskite phase, while there existed the second phase in the SBTV powders and ceramics. All ceramics showed a predominant（001） orientation with small amounts of（115） and（200） orientation. The SBT0 was composed of rodlike grains, and the SBT1 had rodlike and platelike grains; while all SBTV ceramics consisted of platelike grains. Simultaneously V-doped caused crystal lattice distortion and α-fringe can be oberserved in SBTV ceramics. In addition, due to well-oriented grains, dielectric properties of SBT and SBTV ceramicss were poor, and due to the second phase, dielectric properties of the SBTV ceramics was worse. The paroferroelectric transition temperature of SBT1, SBTV1 and SBTV2 was about 350℃. In particular during the sintering the valence state of vanadium ions was changed and strong relaxor-like dielectric relaxation at the ferroelectric transition temperature was observed.更多还原