钨青铜型结构PBNN压电陶瓷电场-应变特性研究

对钨青铜结构型的压电陶瓷［Pb_x（Ba．Sr）_1-x］₄（Na_0．88Li_0．12）₂Nb₁₀O₃₀，x＝0．64（PBNN）的逆压电效应的应变（S）随电场（E）变化特性进行了研究，研究表明该材料的S-E线性好，滞后小．是一种制备随动型压电微位移器的优良材料．从X射线结构分析和S-E变化关系精细测量分析表明，该材料不存在钙钛矿结构型PZT系压电陶瓷（属赝立方铁电相）中由于c←→a，c←→b三晶轴在外电场下互换形成的畴的90°转向，仅有畴的180°转向．这是它S-E特性优良的原因．测量表明，其S-E关系在～350V／mm较高场强处斜率呈现～5％的微小突增，认为这是由于它属假正交晶系，在较强外场下轴长几乎相等的a、b轴间互换对应变的贡献所致．

Characterization of Strain vs Field of PBNN Piezoelectric Ceramic withTungsten Bronze Structure

The characterizations of strain S with electric E in converse piezoelectric effect for Pb_x(Ba, Sr)_1-x]₄(Na_0.88Li_0.12)₂Nb₁₀O₃₀ x=0.64 (PBNN) piezoelectric ceramic with tungsten bronze (T.B.) structure were studied. The excellent micro-displacement properties, such as high linearity, low hysteresis and high coercive field, were exhibited for PBNN ceramic, which were suitable to prepare servo piezoelectric actuators. According to X-ray diffraction structure analysis and measurement results of the relation of S with E, it was shown that in the PBNN piezoelectric ceramic with T.B. structure only the 180° switch of the domain exists without 90° switch of the domain, which inherently exists in PZT based piezoelectric ceramics with peroveskite (P.S.) structure. For PBNN ceramic the excellent characterization of S with E was due to their no 90° switch of the domain. It is found that by more carefully measuring and analyzing the curve of S with E a slight increase of slope (about 5%) occurs at a higher electric field ～350V/mm, which had been explained from pseudo-orthorhombic crystal structure of PBNN ceramic.