Effect of non-stoichiometry on the densification, phase purity, microstructure, crystal structure, and dielectric loss of Ba(Co1/3Nb2/3)O-3 ceramics

摘要

The structural, vibrational, densification, and microwave properties of Ba(Co1/3Nb2/3)O-3 ceramics with small compositional variations along several tie lines in the ternary BaO-CoO-Nb2O5 diagram were studied. The results showed that very small deviation from stoichiometric Ba(Co1/3Nb2/3)O-3 composition has profound effect on Qxf, degree of ordering, densification, and phase assemblage. The 0.94 Ba(Co1/3Nb2/3)O-3-0.06 Ba5Nb4O15 ceramic has the highest Qxf value (71 THz) - a value two times larger than that of stoichiometric Ba(Co1/3Nb2/3)O-3 (36 THz). Transformation from the (partial) disordered distribution of Co and Nb cations to 1:2 ordered arrangement in the octahedral sites was found to increase the Q factor of the high density and single phase ceramics. It was also observed that formation of very small amount of Ba9CoNb14O45 second phase degraded Qxf value severely for the dense and highly ordered Nb-rich and Ba-deficient ceramics. (C) 2017 Elsevier Ltd. All rights reserved.