Microwave dielectrics: solid solution, ordering and microwave dielectric properties of $(1−x)$Ba(Mg$_{1/3}$Nb$_{2/3}$)O$_3$−$x$Ba(Mg$_{1/8}$Nb$_{3/4}$)O3 ceramics

[摘要] The effect of Ba(Mg$_{1/8}$Nb$_{3/4}$)O$_3$ phase on structure and dielectric properties of Ba(Mg$_{1/3}$Nb$_{2/3})O$_3$ was studied by synthesizing $(1−x)$Ba(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$−$x$Ba(Mg$_{1/8}$Nb$_{3/4}$)O$_3$ ($x = 0,$ 0.005, 0.01 and 0.02) ceramics. Superlattice reflections due to 1:2 ordering appear as low as 1000$^{\circ}$C. Ba(Mg$_{1/3}$Nb$_2/3}$)O$_3$ forms solid solution with Ba(Mg$_{1/8}$Nb$_{3/4}$)O$_3$for all ‘$$x’ values studied until 1350$^{\circ}$C. Ordering as confirmed by powder X-ray diffraction pattern, Raman study andHRTEM. Ceramic pucks can be sintered to density $>$92% of theoretical density. Temperature and frequency-stable dielectricconstant and nearly zero dielectric loss ($\tan \delta$) were observed at low frequencies (20 MHz). The sintered samples exhibit dielectric constant ($\epsilon_\tau$) between 30 and 32, high quality factor between 37000 and 74000 GHz and temperature coefficient of resonant frequency ($\tau_f$ ) between 21 and 24 ppm$^{\circ}$C$^{−1}$.

[学科分类] 材料工程

[关键词] Resonators;complex perovskites;X-ray diffraction;dielectric properties;high $Q$.