(1-3x)NBT-2xKBT-xBT系无铅压电陶瓷性能研究R&D

通过XRD分析,发现该体系陶瓷都能形成单一的钙钛矿型固溶体,并在0.025≤x≤0.035范围内具有三方和四方共存结构,为该体系的准同型相界。当x=0.035时,陶瓷的压电常数d33达到150 pC/N,平面机电耦合系数kp达到0.297 7,均高于相应两元体系的压电性能。测定了该体系陶瓷材料的介电常数–温度曲线和电滞回线,发现该体系陶瓷的介电温谱都存在两个介电反常峰,分别对应于陶瓷材料的铁电–反铁电和反铁电–顺电相变。同时,该体系陶瓷具有弛豫铁电体性质。

Study on Dielectric and Piezoelectric Properties of Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3-BaTiO3 Lead-free Piezoceramics System

XRD results show that the crystalline structure of the investigated materials were perovskite. The morphotropic phase boundaries (MPB) of the system between rhombohedral and tetragonal locates in the range of x = 0.025 ~ 0.035, which exhibit the best piezoelectric proiperties. The piezoelectric constant d33 reached to 150 pC/N and planar electromechanical coupling factor kp enhanced to 0.2977 at x = 0.035, which are better than that of the binary lead-free piezoceramics system of NBT-KBT and NBT-BT. It is also found that the ceramic samples are relaxor ferroelectricity from the patterns of dielectric constant as a function of temperature. Two dielectric constant abnormal peaks exists in the dielectric constant vs temperature which corresponding to the phase transitions of ferroelectric to antiferroelectric and antiferroelectric to paraelectric phases by means of observation of different temperature hysteresis loops.