无铅压电陶瓷铌酸钾钠的常压烧结及其电学性能

NORMAL SINTERING OF LEAD-FREE PIEZOCERAMIC POTASSIUM SODIUM NIOBATE AND ITS ELECTRICAL PROPERTIES

用常压烧结方法制备了Na0.5K0.5NbO3(NKN)无铅压电陶瓷。研究了烧结温度与NKN陶瓷的密度、结构以及电学性能的关系。结果表明:NKN陶瓷与KNbO3相似为正交结构,烧结温度超过1080℃时,出现无压电性第二相。在很小的温度范围内(1020～1100℃)烧结体密度有显著不同,当烧结温度为1080℃时,NKN陶瓷烧结密度达到最大值(4.22g/cm3,相对密度为92%)。经1060℃烧结的NKN陶瓷其压电常数最高,达到122pC/N;Curie温度为409℃;矫顽场为9kV/cm;剩余极化强度为15μC/cm2。

Potassium sodium niobate ceramic with a nominal composition of Na0.5K0.5NbO3 （NKN） was fabricated successfully by sintering at 1 020-1 100℃ and normal pressure. The effect of sintering temperature on the density, structure and the electric properties of NKN ceramics were investigated. The results show that the crystal phase of the NKN ceramics is an orthorhombic structure similar to that of KNbO3 ceramics, a second phase formed when the sintering temperature is higher than 1 080℃. The density of the sintered NKN ceramics changed dramatically in a narrow temperature range of 1 020--1 100℃. The density of the ceramics sintered at 1 080℃ reached a maximum value of 4.22 g/cm^3 （92% of the theoretical density）. The ceramic sintered at 1 060℃ shows a maximum piezoelectric coefficient of about 122 pC/N and a maximum Curie temperature of 409℃, and the coercive field and remanent polarization are 9 kV/cm and 15μC/cm2, respectively.