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

Abstract

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 −xBa(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 • 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 • C. Ordering was confirmed by powder X-ray diffraction pattern, Raman study and HRTEM. Ceramic pucks can be sintered to density >92% of theoretical density. Temperature and frequency-stable dielectric constant and nearly zero dielectric loss (tan δ) were observed at low frequencies (20 MHz). The sintered samples exhibit dielectric constant (ε r) between 30 and 32, high quality factor between 37000 and 74000 GHz and temperature coefficient of resonant frequency (τ f) between 21 and 24 ppm • C −1 .