【摘要】 采用铌铁矿预产物合成法制备了锂盐[碳酸锂(Li2CO3),硝酸锂(LiNO3),氟化锂(LiF)]助烧0.68Pb(Mg1/3Nb2/3)O3–0.32 PbTiO3(PMN–PT68/32)弛豫铁电陶瓷。用X射线衍射分析陶瓷相组成并测试PMN–PT68/32的压电性能。结果表明:所有陶瓷样品均为纯钙钛矿相,无任何其它杂相。添加Li2CO3和LiNO3可以使PMN–PT68/32陶瓷压电性能有一定提高。添加LiF可以使PMN–PT68/32陶瓷压电性能提高很多,其中1150℃烧结添加LiF样品的压电性能为:平面机电耦合系数(kp)约为64%;厚度机电耦合系数(kt)约为54%;压电常数(d33)约为623pC/N;机械品质因数(Qm)约为96。添加Li2CO3和LiNO3样品只发生Li+在PMN–PT68/32的B位置换并产生氧空位。添加LiF样品可以通过F–取代反应产生铅空位来补偿Li+取代产生的氧空位。因此,LiF作为助烧剂的PMN–PT68/32陶瓷的优良压电性能不仅源于低温液相烧结以及阳离子Li+的取代,而且很大程度上源于阴离子F–的取代。更多还原

【Abstract】 Relaxor ferroelectric 0.68 Pb(Mg1/3Nb2/3)O3-0.32 PbTiO3 (PMN-PT68/32) ceramics with lithium salts (lithium carbonate (Li2CO3),lithium nitrate (LiNO3),lithium fluoride (LiF)) as sintering aids were prepared by the columbite precursor method. The phase composition of the ceramic samples was investigated by X-ray diffraction (XRD),and the piezoelectric properties of these ce-ramics were measured. The results show that pure perovskite phase is obtained for all the specimens and no other phase is detected. Moreover,the piezoelectric properties of PMN-PT68/32 ceramics with LiF sintering aids were improved more than those of PMN-PT ceramics with Li2CO3 or LiNO3 sintering aids,and the sample with LiF addition sintered at 1 150 ℃ had good piezoelec-tric properties: a piezoelectric planar coupling coefficient (kp) of 64%,a piezoelectric thick coupling coefficient (kt) of 54%,a piezo-electric constant (d33) of 623 pC/N,and a mechanical quality factor (Qm) of 96. The sample with Li2CO3 or LiNO3 addition may only have cationic (Li+) substitution at the B-site of PMN-PT68/32 with oxygen vacancies formation,but the sample with LiF addition may have anionic (F-) substitution with lead vacancies formation,which may be compensated with oxygen vacancies formed by cationic (Li+) substitution. So the good piezoelectric properties of PMN-PT68/32 ceramics with LiF sintering addition may be attributed to not only low temperature liquid phase sintering and cationic (Li+) substitution but also mainly anionic (F-—O2-) substitution.更多还原