Phase and Microstructure Evaluation and Microwave Dielectric Properties of Mg1−xNixSiO3 Ceramics
The ceramics were prepared using the solid-state reaction method and their phase, microstructure and microwave dielectric properties were investigated. A single-phase clinoenstatite system with monoclinic structure (space group P21/c) was confirmed through x-ray diffraction (XRD) analysis for the compositions with x ≤ 0.1. The compositions with x ≥ 0.15 contain SiO2 and (Mg1−xNix)2SiO4 phases only as confirmed from the XRD data of their sintered samples. The unit cell volume was decreased while the theoretical density was increased with increase in x from 0 to 0.1. A decrease in dielectric constant (εr) while an increase in unloaded quality factor multiplying the resonant frequency (Qufo) and temperature coefficient of resonant frequency (τf) was observed with increase in Ni content from 0 to x = 0.1. In the present study, εr ∼ 6.10, Qufo ∼ 118,702 GHz and τf ∼ −10 ppm/°C was achieved for the composition with x = 0.1 sintered at 1425°C for 9 h. The material is a good candidate for millimeter wave applications.