(1-x)(K<sub>0.5</sub>Na<sub>0.5</sub>)NbO<sub>3</sub>-xBa<sub>0.985</sub>La<sub>0.01</sub>TiO<sub>3</sub>无铅陶瓷的微观结构及电性能研究

Abstract

采用传统固相烧结法制备(1−x)(K0.5Na0.5)NbO3-xBa0.985La0.01TiO3 (KNN-xBLT, x = 0.01、0.02、0.04、0.05)无铅陶瓷并研究了BLT掺杂对KNN陶瓷性能的影响。结果表明：BLT的掺杂抑制了KNN-xBLT陶瓷晶粒的生长使陶瓷晶粒尺寸更均匀。在室温至350℃范围内，KNN-xBLT陶瓷的介电常数随着BLT掺杂量的增加而增大且居里温度向低温方向移动。0.95KNN-0.05BLT陶瓷是一种弛豫铁电体且在室温至350℃范围内最大介电常数4000，介电损耗小于0.02，暗示其在高温陶瓷电容器介质材料方面的应用潜力。在研究的组成范围内，KNN-xBLT陶瓷的相结构随BLT掺杂量的增加由正交相转变为四方相，当x = 0.04时，KNN-xBLT陶瓷为正交和四方两相共存。0.96KNN-0.04BLT陶瓷因正交相和四方相共存压电性能有所提高(d33 = 185 pC/N, kp = 0.39)，但距铅基压电陶瓷的性能还有差距。 The (1−x)(K0.5Na0.5)NbO3-xBa0.985La0.01TiO3 (KNN-xBLT, x = 0.01, 0.02, 0.04, 0.05) lead-free ceramics were prepared by the conventional solid-state sintering method. It was found that the phase structure of KNN-xBLT ceramics changed from the orthorhombic phase to the tetragonal phase with the increase of BLT content. When x = 0.04, the phase structure of KNN-xBLT ceramics was orthorhombic and tetragonal phase coexisting. The density increased and the grain size decreased with BLT increased. The dielectric constant of the KNN-xBLT ceramics increased with the increase of BLT content and the Curie temperature shifted to the low temperature in the temperature range from room temperature to 350˚C. The 0.95KNN-0.05BLT ceramic was a relaxor ferroelectric with high dielectric constant of ɛ > 4000 and the low dielectric loss of tanδ < 0.02 in the temperature range from room temperature to 350˚C. These results indicate that 0.95KNN-0.05BLT ceramics are promising candidate materials for preparing the high temperature multilayer ceramics capacitors. The 0.96KNN-0.04BLT ceramics obtain the optimum piezoelectric properties: d33 = 185 pC/N, kp = 0.39.