Synthesis of single phase MgTiO3 and influence of Sn4+ substitution on its structural, dielectric and electrical properties

Abstract

In this work, synthesis of single-phase MgTiO3 and Mg(Ti0.95Sn0.05)O3 ceramics through conventional solid state mixed oxide route using Mg(OH)2 or MgO as raw material was investigated. The phase purity of prepared specimens was examined using X-ray diffraction; bond characteristics were determined via Raman spectroscopy, dielectric properties at low frequency were measured by Impedance spectroscopy and dielectric properties at microwave frequency were measured by vector network analyzer. The properties of Mg(OH)2 based ceramics were also compared to that of MgO based ceramics in frequency range of 10 kHz-3 MHz and temperature range of 298–468 K. It was observed that Mg(OH)2 based materials exhibited not only low losses (tan δ) and low relative permittivity (ϵr) but also possessed smaller value of temperature coefficient of resonant frequency (τf) in comparison to that of MgO based materials. Dielectric and electrical properties of MgTiO3 were further improved by partial replacement of tetravalent cations Ti4+ with Sn4+. The mechanism of electrical conduction for the synthesized specimens was also studied using Jonscher power law and activation energy was evaluated using Arrhenius equation. Best dielectric properties at room temperature in 10 kHz-3 MHz frequency range were displayed by Mg(OH)2 based Mg(Ti0.95Sn0.05)O3 compound having tan δ of 2.32 × 10−4, ϵr of 14.61 and τf of −39.7 ppm/K at 100 kHz frequency. At 15 GHz Mg(OH)2 based Mg(Ti0.95Sn0.05)O3 exhibited tan δ of 2.73 × 10−2 and ϵr of 14.12. This material could be utilized for fabrication of multilayer capacitors, dielectric resonators, filters, antennas, buffer layers and protective coatings.