Effect of calcination and sintering temperature on dielectric properties of giant dielectric Ti0.9(In0.5Nb0.5)0.1O2 ceramics

Abstract

Capacitors have an advantage over batteries with respect to the endurance for charge - discharge cycling and power density. Capacitors can replace Li-ion batteries if energy density can be increased significantly. Use of electric double-layer capacitor (EDLC) is restricted because of the relatively low energy density of EDLC in comparison with lithium ion battery and the leakage of liquid electrolyte from packages. The capacitance density of multi-layered ceramic capacitors (MLCCs) has been increased one million times by reducing the thickness of dielectric layer down to 1 μm in last three decades. However, in case of BaTiO3 based capacitor, dielectric constant decreases with grain size beyond 1μm and that limits the increase in capacitance density. Those problems can be solved if we can make new solid state capacitors with very high capacitance and energy density. In view of that urgent need, the search for materials with giant permittivity (GP, ε′ = 104–105 in a radio frequency range) has been attracting considerable attention for many years. Very recently, GP with low dielectric loss was reported in (In, Nb) co-doped rutile TiO2 polycrystalline ceramics. Here, we investigated the dielectric properties of Ti0.9(In0.5Nb0.5)0.1O2 ceramics and prepared by the solid-state method at various calcination and sintering temperatures. Both calcination and sintering temperatures have a significant effect on the density and grain size, which are closely related to dielectric properties. The calcination temperature has a great influence on the the grain boundary and in effect modifies the dielectric properties. Impedance spectroscopy was used to explain the mechanism of giant permittivity.