Journal of the American Ceramic Society, Vol.103, No.11, 6369-6377, 2020
Crystal structure, phase compositions, and microwave dielectric properties of malayaite-type Ca(1-)(x)Sr(x)SnSiO(5)ceramics
Low-permittivity Ca1-xSrxSnSiO5(0 <= x <= 0.45) microwave dielectric ceramics were prepared via traditional state-reaction at 1400 degrees C-1450 degrees C for 5 hours. Moreover the microwave dielectric properties of SnO(2)ceramic were obtained for the first time. SnO(2)ceramic was difficult to densify, and SnO(2)ceramic (rho(rel) = 65.1%) that was sintered at 1525 degrees C exhibited the optimal microwave dielectric properties of epsilon(r) = 5.27,Q x f = 89 300 GHz (at 14.5 GHz), and tau(f) = -26.7 ppm/degrees C. For Ca1-xSrxSnSiO5(0 <= x <= 0.15) ceramics, Sr(2+)could be dissolved in the Ca(2+)site of Ca(1-)(x)Sr(x)SnSiO(5)to form a single phase, and the partial substitution of Ca(2+)by Sr(2+)could improve the microwave dielectric properties of CaSnSiO(5)ceramic. Secondary phases (SnO(2)and SrSiO3) appeared at 0.2 <= x <= 0.45 and could adjust the abnormally positive tau(f)value of CaSnSiO(5)ceramic. The highestQ x fvalue (60 100 GHz at 10.4 GHz) and optimal microwave dielectric properties (epsilon(r) = 9.42,Q x f = 47 500 GHz at 12.4 GHz, and tau(f) = -1.2 ppm/degrees C) of Ca(1-)(x)Sr(x)SnSiO(5)ceramics were obtained atx = 0.05 and 0.45, respectively.