Sr(Ga 0.5 Nb 0.5 ) 1− x Ti x O 3 Low‐Loss Microwave Dielectric Ceramics with Medium Dielectric Constant

• Published in: Journal of the American Ceramic Society Vol. 98; no. 8; pp. 2534 - 2540
• Main Authors: Ma, Pian Pian, Liu, Xiao Qiang, Zhang, Fa Qiang, Xing, Juan Juan, Chen, Xiang Ming
• Format: Journal Article
• Language: English
• Published: 01.08.2015
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.13655

The microwave dielectric properties of Sr(Ga 0.5 Nb 0.5 ) 1− x Ti x O 3 ( x  = 0, 0.1, 0.2 and 0.3) ceramics have been investigated together with their microstructures. Single‐phase solid solutions are achieved in this series of ceramics. The ordering features are comprehensively analyzed by transmission electron microscopy and Raman spectroscopy. Local 1:1 ordering in B ‐site leads to a double‐cubic structure with space group , while Ti substitution disrupts this 1:1 ordering between Ga and Nb, and the metastable ordering between Ti and (Ga + Nb) is speculated to form due to their large size difference. The dielectric constant and temperature coefficient of resonant frequency increase nonlinearly as x increases, while the Qf value decreases gradually. The variation trend of Qf value is mainly attributed to the intrinsic loss because of the increasing vibrational anharmonicity by Ti substitution. The ordering transition from short coherence, long‐range ordering to short‐range ordering with increasing Ti content has an agreeable and weak effect on the Qf value. The best combination of microwave dielectric properties is achieved for the composition of x  = 0.3: ε r   = 46.6, Qf   = 42 200 GHz and τ f  = 5.0 ppm/°C.