Crystal structure, phase compositions, and microwave dielectric properties of malayaite‐type Ca <sub>1−</sub> <i> <sub>x</sub> </i> Sr <i> <sub>x</sub> </i> SnSiO <sub>5</sub> ceramics
Kang Du, Jun Fan, Zheng‐Yu Zou, Xiaoqiang Song, Wenzhong Lü, Wen Lei
Abstract
Abstract Low‐permittivity Ca 1− x Sr x SnSiO 5 (0 ≤ x ≤ 0.45) microwave dielectric ceramics were prepared via traditional state‐reaction at 1400°C‐1450°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 ( ρ rel = 65.1%) that was sintered at 1525°C exhibited the optimal microwave dielectric properties of ε r = 5.27, Q × f = 89 300 GHz (at 14.5 GHz), and τ f = −26.7 ppm/°C. For Ca 1− x Sr x SnSiO 5 (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 SrSiO 3 ) appeared at 0.2 ≤ x ≤ 0.45 and could adjust the abnormally positive τ f value of CaSnSiO 5 ceramic. The highest Q × f value (60 100 GHz at 10.4 GHz) and optimal microwave dielectric properties ( ε r = 9.42, Q × f = 47 500 GHz at 12.4 GHz, and τ f = −1.2 ppm/°C) of Ca 1− x Sr x SnSiO 5 ceramics were obtained at x = 0.05 and 0.45, respectively.