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

Fine-tuning of the temperature coefficients of capacitance and dielectric c onstant of magnesium orthostannate (Mg2SnO4) has been attempted by means of Sn (IV) and Zr (IV) oxide incorporation as a second phase. The additives w ere 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 a nd/or SnO2 and sintered in the temperature range 1500 degrees -1600 degrees C for up to 6 h. Electrical measurements using an AC immittance spectroscop ic technique over the temperature range 25 degrees -300 degreesC, on Mg2SnO 4 compacts containing 5 wt.% of additives and sintered at 1500 degreesC/ 6 h, were carried out. Data analyses revealed that the capacitance and the de rived dielectric constant remained invariant over more than 3 decades of fr equency 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 capac itance (TCC) and temperature coefficient of dielectric constant (TCK) as it resulted in smaller dependence of capacitance and dielectric constant comp ared to pure Mg2SnO4. Typically, the TCC values were 5 and 30 ppm/degreesC and TCK values were 20 and 30 ppm/degreesC for 5 wt.% ZrO2- and 5 wt.% SnO2 - added Mg2SnO4, respectively, in the temperature range 25 degrees -300 deg reesC. (C) 2001 Kluwer Academic Publishers.