Neutron powder diffraction study and B-site ordering in microwave dielectric ceramics Ba(Ca1/3Nb2/3)O3

Microwave dielectric powder Ba(Ca1/3Nb2/3)O-3 with high B-site cation ordering was synthesized by the molten salt method. Neutron powder diffraction (NPD) and Raman scattering spectra were introduced to investigate tire variable ordering degree during the sintering process. It was revealed that the as-synthesized Ba(Ca1/3Nb2/3)O-3 powder had a nearly completely ordered structure, and the sintered Ba(Ca1/3Nb2/3)O-3 presented a bit higher ordering degree based on the detailed quantitative NPD Rietveld full profile fitting. The complete Raman mode assignment for the Ba(Ca1/3Nb2/3)O-3 was presented. The phonon bands could also confirm the order-disorder structural model and increasing ordering degree with the increasing sintering temperature. Final microwave dielectric measurements on sintered samples showed the present compound to tailor other dielectric materials for microwave applications with the dielectric properties of epsilon(r) = 47.11, and Qf = 1389 GHz, and tau(f) was about 113 ppm/degrees C. (c) 2008 Elsevier Masson SAS. All rights reserved.