Fine-tuning of temperature coefficients of capacitance (TCC) and dielectric constant (TCK) of Mg2SnO4 via second phase addition

Abstract

Fine-tuning of the temperature coefficients of capacitance and dielectric constant of magnesium orthostannate (Mg₂SnO₄) has been attempted by means of Sn (IV) and Zr (IV) oxide incorporation as a second phase. The additives were also employed to enhance the density and minimize or eliminate porosity at lower sintering temperatures. Phase-pure magnesium stannate powder was synthesized via conventional solid-state reaction. It was mixed with ZrO₂ and/or SnO₂ and sintered in the temperature range 1500°–1600°C for up to 6 h. Electrical measurements using an AC immittance spectroscopic technique over the temperature range 25°–300°C, on Mg₂SnO₄ compacts containing 5 wt.% of additives and sintered at 1500 °C/ 6 h, were carried out. Data analyses revealed that the capacitance and the derived dielectric constant remained invariant over more than 3 decades of frequency in the kilo to megahertz regime. It was also found that addition of ZrO₂ and SnO₂ has a benign effect on both temperature coefficient of capacitance (TCC) and temperature coefficient of dielectric constant (TCK) as it resulted in smaller dependence of capacitance and dielectric constant compared to pure Mg₂SnO₄. Typically, the TCC values were 5 and 30 ppm/°C and TCK values were 20 and 30 ppm/°C for 5 wt.% ZrO₂- and 5 wt.% SnO₂- added Mg₂SnO₄, respectively, in the temperature range 25°–300°C.