Effect of temperature on dielectric properties of Si₃N ₄/SiO₂ composite and silica ceramic

In this article, the dielectric properties of Si₃N₄ nanowires reinforced silica ceramic composites compared with pure silica ceramics were investigated by using impedance analyzer, at the frequencies from 10³ to 10^7.5 Hz and the measuring temperature ranging from 20 to 800 °C. Then the effects of the measuring and sintering temperature on the dielectric behavior of the samples were discussed. It was found that there existed different dielectric behaviors between the pure and composite specimens. Among the measuring temperature studied, the composite displayed better dielectric property as compared with the pure ceramic. The superiority exhibited distinctly at high temperature, which could be explained by the theory of dielectric polarization. For the effect of sintering temperature on the dielectric property, the results showed that the dielectric constants increase with the increase of sintering temperature, which can be mostly associated with the variety of sample density. However, the dielectric losses of both ceramics show a little dependence of the sintering temperature.