Dielectric properties and relaxor behavior of high Curie temperature (Ba_(o.85)Ca_(o.15))(Zr_(o.1)Ti_(o.9))O_3-Bi(Mg_(o.5)Ti_(o.5))O_3 Lead-free ceramics

摘要

The (l-x)(Ba_(o.85)Ca_(o.15))(Zr_(o.1)Ti_(o.9))O_3-xBi(Mg_(o.5)Ti_(o.5))O_3 [(l-x)BCZT-xBMT, x=0.1-0.7] lead-free solid solution ceramics were prepared by the conventional mixed oxide method. The phase structure was investigated by X-ray diffraction and results show that a single perovskite phase was obtained in all of these samples, suggesting that the added BMT diffused into BCZT to form a solid solution. Dense ceramics with relative densities > 95% were obtained, and a small amount of BMT (< 50 mol%) acted as grain growth promoter, had an evident effect on grain size growth. Further increase of the BMT content inhibited the grain growth of BCZT samples. Temperature dependence of the dielectric properties showed that all the BCZT-BMT solid solution ceramics exhibited relaxor-like characteristics. With increasing BMT content, the Curie temperature was first increased and then decreased, giving a maximum value of 218 °C for the 0.4BCZT-0.6BMT composition. Furthermore, stable dielectric constants and low losses were obtained with 0.5 < x < 0.7 in the wide temperature range, indicating that the system possess potential for high-temperature application.