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

A new microwave dielectric ceramic NiTiTa2O8 with tetragonal cell of the trirutile-type structure was reported in this study. The crystal structure, microstructure, sintering behavior, and microwave dielectric properties of NiTiTa2O8 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. NiTiTa2O8 ceramics sintered at 1350 degrees C possessed the most stable structure with refined parameters being a = b = 4.6869(2) angstrom, c = 9.0726(1) angstrom and V-unit = 199.617 angstrom(3). The measured dielectric constants, all sensitive to the density of samples, were lower than those of theoretical values. The Q x f values were largely linked to the packing fraction and relative density. The temperature coefficient of resonance frequency (tau(f)) were mainly influenced by the oxygen distortions of the octahedron. Excellent dielectric properties of epsilon(r) = 39.86, Q x f = 25,051 GHz and tau(f) = 75 ppm/degrees C for NiTiTa2O8 ceramics could be obtained as sintering temperature was 1350 degrees C. (C) 2019 Elsevier B.V. All rights reserved.