A glaserite-like ternary molybdate K(Mg0.5Zr0.5)(MoO4)2: Synthesis, thermal expansion, and ionic conductivity

Abstract

A ternary molybdate K(Mg0.5Zr0.5)(MoO4)2 was successfully synthesized using the sol-gel method and traditional solid-phase reactions technique. The synthesis time reduced from 200 to 15 h and smaller particles (20–3 μm) were reached by the sol-gel method. Phase purity and crystal structure were confirmed by X-ray diffraction (XRD) analysis with Rietveld refinement. The surface morphology was characterized using a scanning electron microscope (SEM). Using the powder XRD data recorded over 30–550 °C, the principal components of the thermal expansion tensor were determined. K(Mg0.5Zr0.5)(MoO4)2 can be classified as a high-expansion material (αV = 160 × 10−6 °С−1 at 500°С). At elevated temperatures, the compound exhibits significant ionic conductivity, with values reaching 4.2·10−3 S/cm at 650°С, and oxygen ions are the probable charge carriers with activation energy Ea = 0.51 eV.