Study On Properties Of Bismuth Potassium Titanate-based Lead-free Piezoelectric Ceramics

Piezoelectric ceramics,as one of the important functional materials,have been widely used in filters,actuators,sensors,transformers,transducers and other electronic devices.Based on the requirements on environmental protection,the development of lead-free piezoelectric ceramics becomes a focus of piezoelectric ceramic research.Among them,(K_1/2Bi_1/2)TiO₃-based lead-free piezoelectric ceramics has received wide-spread attention in recent years.In the research of this topic,we hope that through the compound modification to obtain(K_1/2Bi_1/2)TiO₃-based lead-free piezoelectric ceramics with excellent electric performance.In this paper,(K_1/2Bi_1/2)TiO₃-xCuSb₂O₆?KBT-xCS?and?1-x?(K_1/2Bi_1/2)TiO₃-xBi(Mn_2/3Sb_1/3)O₃??1-x?KBT-xBMS?lead-free piezoelectric ceramics were prepared by the conventional mixed oxide method.Microstructures were studied according X-ray diffraction and scanning electron microscopy.Dielectric,ferroelectric,piezoelectric and field induced strain properties were measured by multi-frequency inductance capacitance resistance?LCR?analyzer,ferroelectric tester,d₃₃ meter etc.According,composition and temperature dependence evolution of these properties were discussed.For KBT-xCS ceramics,density measurement and SEM observation indicates that the addition of CS can improve the sintering activity of ceramics and promote the grain growth,thus presenting good sintering ability.The introduction of CS forms the mixed phase region of tetragonal and pseudocubic phases with KBT,and gradually reduces the tetragonal degree of KBT-CS ceramics.Moreover,the depolarization temperature of CS can still maintain a high level after the introduction of CS.When the CS content is 0.2%,the optimal piezoelectric coefficient d₃₃=97 pC/N is obtained.For?1-x?KBT-xBMS ceramics,the significantly improved sintering behavior of(K_1/2Bi_1/2)TiO₃ ceramics though adequate BMS addition provides a basis to develop the electric properties.Pure perovskite structure was achieved for all investigated compounds.The introduced BMS forms a mixed phase structure of tetragonal and pseudocubic,and diminishes the tetragonality of KBT gradually.Meanwhile,the relaxor behavior of?1-x?KBT-xBMS was enhanced distinctly with increasing the BMS content.The composition 0.985KBT-0.015BMS exhibits optimal dielectric,piezoelectric,electromechanical performances and thermal stability:?_r=689,d₃₃=104pC/N,k_p=17.5%,Q_m=175,T_d=205?,and T_m=380?.At the same time,the addition of?1-x?(K_1/2Bi_1/2)TiO₃-xBi(Mn_2/3Sb_1/3)O₃ not only improves the densification and crystallinity of(K_1/2Bi_1/2)TiO₃ based ceramics but also widens the sintering temperature span,which is ascribed to the lowered temperature and increased viscosity of liquid phase during the sintering.In the widened sintering temperature range,the samples present a stable phase structure and the excellent electric properties.