A Low-Dielectric-Constant and Low-Loss CaY2Al4SiO12 Microwave Dielectric Ceramic with Cubic Structure

Abstract

In this work, a silicate ceramic, CaY₂Al₄SiO₁₂ (CYASO), with a low dielectric constant and low loss was prepared using traditional solid-state methods. X-ray diffraction (XRD) refinement analysis shows that the CYASO material crystallized into a phase with an Ia-3d space group and an impurity peak. The orthogonal cubic structure of the CYASO ceramic was confirmed through transmission electron microscopy (TEM), and the structure exhibited an orderly layered arrangement. The internal microstructure was characterized using scanning electron microscopy (SEM), which showed that the sample’s relative density reached 97.8%. We discuss the correlation between the full width at half maximum (FWHM) of the Raman matrix corresponding to the vibration mode of the symmetric bending mode of AlO₄ at the Raman shift of 855 cm⁻¹ and the Q × f value. Additionally, the analysis focused on the various factors that influence the dielectric constant, including density, secondary phase, and porosity changes. The ceramics exhibited remarkable microwave dielectric properties (ε_r = 8.7, Q × f = 34,700 GHz, τ_f =  −35 ppm/°C) when calcined at 1425°C. CYASO ceramic shows great capacity as a microwave dielectric material.