Crystal structure and microwave dielectric properties of a new low-loss ceramic NiTiTa2O8

Abstract A new microwave dielectric ceramic NiTiTa 2 O 8 with tetragonal cell of the trirutile-type structure was reported in this study. The crystal structure, microstructure, sintering behavior, and microwave dielectric properties of NiTiTa 2 O 8 ceramics were investigated. Crystallographic parameters were acquired by Rietveld refinement and lattice potential energy, theoretical dielectric constant, packing fraction as well as distortions of the octahedron were calculated. NiTiTa 2 O 8 ceramics sintered at 1350 °C possessed the most stable structure with refined parameters being a = b = 4.6869(2) A, c = 9.0726(1) A and V unit  = 199.617 A 3 . The measured dielectric constants, all sensitive to the density of samples, were lower than those of theoretical values. The Q  ×  f values were largely linked to the packing fraction and relative density. The temperature coefficient of resonance frequency ( τ f ) were mainly influenced by the oxygen distortions of the octahedron. Excellent dielectric properties of e r  = 39.86, Q  ×  f  = 25,051 GHz and τ f  = 75 ppm/°C for NiTiTa 2 O 8 ceramics could be obtained as sintering temperature was 1350 °C.