Investigation on phase and microstructures of a temperature stable high-Q Li2Zn0.95Sr0.05Ti3O8 microwave dielectric ceramic
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A temperature stable high-Q Li2Zn0.95Sr0.05Ti3O8 microwave dielectric ceramic is fabricated by conventional solid-state reaction route and the phase composition, microstructures and microwave dielectric properties are investigated in this paper. The bulk density and FESEM results indicate that this ceramic can be well-sintered at 1075 °C for 4 h. Since the difficulty in Sr2+ ions diffused into the Li2ZnTi3O8 crystal lattice to form solid solutions owing to the large radii difference between Sr2+ (1.44Å) and Zn2+ (0.74Å), there are three phases including the main phase Li2ZnTi3O8 and the second phase SrTiO3 and unknown phase according to the XRD and element-distribution mapping results. The formation of second phase is advantageous to improve the relative permittivity (εr) and temperature coefficient of resonant frequency (τf), but degrades the quality factor (Q × f) slightly. The Li2Zn0.95Sr0.05Ti3O8 ceramic sintered at 1075 °C/4 h displays a temperature stable high-Q properties: εr = 26.6, Q × f= 62300 GHz, and τf = 0.27 ppm/°C.