Microwave dielectric properties and low-temperature sintering mechanism in (Ca,Bi)(Mo,V)O4 ceramics

In this work, high-quality (Ca1-xBix)(Mo1-xVx)O-4 (0.15 <= x <= 0.5) ceramics with a tetragonal scheelite structure were prepared at sintering temperatures of 800-925 degrees C. Their microstructures, alternating current impedance, and microwave dielectric properties were studied comprehensively. Through scanning electron microscopy and transmission electron microscopy analyses, the low-temperature sintering mechanism was clarified to be the dissolution-precipitation process of small particles in the liquid phase of the grain boundary. The increase in point defects led to an increase in extrinsic loss, which might be the main ex-trinsic factor affecting the Qxf (Q = quality factor = 1/dielectric loss, f = resonant frequency) value. The (Ca0.65Bi0.35)(Mo0.65V0.35)O-4 ceramic sintered at 875 degrees C for 4 h exhibited superior microwave dielectric properties, with permittivity (epsilon(r)) similar to 17, Qxf value similar to 12080 GHz (at 9.86 GHz), and near-zero temperature coefficient of resonance frequency (tau(f)) similar to + 3.6 ppm/degrees C; thus, the ceramic has great potential for the LTCC application. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

High-quality (Ca1-xBix)(Mo1-xVx)O-4 ceramics with a tetragonal scheelite structure were prepared at sintering temperatures of 800-925 degrees C. The increase in point defects led to an increase in extrinsic loss, affecting the Qxf value. The (Ca0.65Bi0.35)(Mo0.65V0.35)O-4 ceramic exhibited superior microwave dielectric properties, showing great potential for LTCC application.