Microstructure and Microwave Dielectric Properties of xCa(Al<subscript>0.5</subscript>Nb<subscript>0.5</subscript>)O<subscript>3</subscript>+(1− x)SrTiO<subscript>3</subscript> Solid Solutions.

The crystal structure evolution and microwave (MW) dielectric properties of xCa(Al0.5Nb0.5)O3+(1− x)SrTiO3 ( xCAN+(1− x)ST, 0≤ x≤1.0, ) dielectric ceramics were investigated. X-ray diffraction patterns illustrated that a single perovskite solid solution could be formed between the two end members; however, minor amount of pyrochlore phase was also detected in the composition range of 0.5≤ x≤0.9. With the increase of x value, the crystal structure gradually evolved from a simple Pm3 m cubic to a monoclinic P21/ n space group with the octahedral tilting and the B-site ordering structure transition subsequently developed. The MW dielectric properties of xCAN+(1− x)ST solid solutions were elaborately investigated and correlated to their crystal structures. The microscopic structure-related thermal parameters in the xCAN+(1− x)ST solid solution were analyzed in terms of the Claussius-Mossotti equation to reveal the original contributors in temperature coefficients. Temperature coefficient-compensated ceramic could be obtained in the xCAN+(1− x)ST system in the range of 0.5< x<0.6. When sintered at 1500°C for 4 h, a dielectric constant ℇr of 37.32, a Qf product of 25 430 GHz, and a τf value of −22.4 ppm/°C MW dielectric ceramic could be obtained in the 0.6Ca(Al0.5Nb0.5)O3+0.4SrTiO3 composition. [ABSTRACT FROM AUTHOR]