Sol-gel synthesis and characterization of MgSO4:Mg(NO3)2 - Al2O3 composite solid electrolytes

Abstract

Composite solid electrolytes in the system (1-x)MgSO4:Mg(NO3)2 - xAl2O3 with x = 0.1-0.6 were synthesized by sol- gel method and analysed by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, energy dispersive X-ray, Fourier transform infrared spec-troscopy and alternating current impedance spectroscopy. Structural analysis revealed solid- solid phase transformation of anhydrous MgSO4 to β - MgSO4 after sintering at 900 °C for 2 hours. Recrystallization of crystalline β-MgSO4 phase was observed for composite samples with x = 0.1 - 0.3. Addition of anhydrous MgSO4 and Mg(NO3)2 as a co-host, resulted in the formation of MgO phase after heat treatment. The conductivities of the composites were in the order of 10-7 S cm-1 at room temperature on account from the formation of a new region of Mg2+|MgO.