Temperature-dependent Raman spectroscopic studies of microstructure present in dipotassium molybdate crystals and their melts

Temperature-dependent Raman spectra of K2MonO3n+1 (n=1, 2, 3) crystals up to and above their melting points were recorded, and their vibration modes in solid and molten states were assigned. Basic structural units and the corresponding cluster forms in molten dipotassium monomolybdates, dimolybdates, and trimolybdates were studied by in situ high-temperature Raman spectroscopic studies together with theoretical calculations, including density functional theory and quantum chemistry ab initio calculation. Anion units of [MoO4](2-), [Mo2O7](2-), and [Mo3O10](2-) were shown to principally exist in molten K2MoO4, K2Mo2O7, and K2Mo3O10, respectively. The mechanisms of the microstructural evolution of K2MonO3n+1 (n=1, 2, 3) crystals while being melted are schematically illustrated. Copyright (c) 2016 John Wiley & Sons, Ltd.