Sintering behavior, phase composition, microstructure, and dielectric characteristics of garnet-type Ca3Fe2Ge3O12 microwave ceramics

This paper describes the solid-state production of a unique yellowish-grey microwave dielectric ceramic, Ca3Fe2Ge3O12 (CFG). Rietveld refinement demonstrated that CFG corresponds to a cubic system (space group 230: Ia 3 d). The relative density of the ceramic initially increased and then decreased with the sintering temperature, reaching a maximum of 96.92% at 1 330 degrees C. According to scanning electron mi-croscopy and energy-dispersive spectroscopy results, the CFG ceramic grains are spherical and consistent in size; furthermore, they have distinct grain boundaries and a uniform distribution of the four con-stituent elements. The CFG ceramic has a superior crystal structure and a high crystallinity, according to transmission electron microscopy. Raman spectroscopy revealed that the Qxf value of the ceramic and the full width at half maximum of the Raman peak are negatively correlated. The ceramic possesses the best overall dielectric characteristics after sintering at 1 330 degrees C for 4 h: er = 10.31, Qxf = 82 636 GHz, and Tf =-45.66 x 10-6 degrees C-1, showing that it is a promising candidate for use in mobile devices.(c) 2023 The Authors. Published by Elsevier B.V. on behalf of The Chinese Ceramic Society. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).