Abstract
In situ high-temperature Raman spectra of polycrystalline KBi(MoO4)2 were recorded from room temperature to 1073 K. Thermal stability of the monoclinic KBi(MoO4)2 was examined by temperature-dependent XRD. The monoclinic phase transformed into the scheelite tetragonal structure at 833 K, and then to the monoclinic phase at 773 K. Quantum chemistry ab initio calculation was performed to simulate the Raman spectra of the structure of KBi(MoO4)2 high-temperature melt. The experimental Raman band at 1023 K was deconvoluted into seven Gaussian peaks, and the calculated results were in good agreement with the experimental data. Therefore, the vibrational modes of Raman peaks of molten KBi(MoO4)2 were assigned. It was confirmed that the isolated structure of [Bi(MoO4)2]− monomer, consisting of Mo6+ centers and Bi3+ sub-centers connected by edge-sharing, mainly exists in the melt of KBi(MoO4)2.
Highlights
Double molybdates have attracted extensive interest due to their potential applications in various fields of science and technology [1]
Double molybdates of monovalent and trivalent cations have the following three characteristics reported by Isupov [18]: (i) there are many combinations of monovalent (Li, Na, K, Rb, Cs, Tl, Ag) and trivalent (Al, Sc, Fe, Ga, Y, In, La-Lu, Bi) elements in compounds, (ii) the number of crystal types of these compounds is large, and (iii) there are numerous reconstructive phase transitions which differ from the displacement transitions
We report the temperature-dependent Raman spectroscopy studies of polycrystalline KBi(MoO4 )2 from room temperature to 1073 K in order to obtain information on the structural changes that occur in this material
Summary
Double molybdates have attracted extensive interest due to their potential applications in various fields of science and technology [1]. Double molybdates of monovalent and trivalent cations have the following three characteristics reported by Isupov [18]: (i) there are many combinations of monovalent (Li, Na, K, Rb, Cs, Tl, Ag) and trivalent (Al, Sc, Fe, Ga, Y, In, La-Lu, Bi) elements in compounds, (ii) the number of crystal types of these compounds is large, and (iii) there are numerous reconstructive phase transitions which differ from the displacement transitions. Double potassium bismuth molybdate KBi(MoO4 ) are generally used as promising hosts for a variety of luminescent RE3+ ions, such as the doped Cr3+ :KCrx Bi1-x (MoO4 ) system [24,25,26]. It was reported that the KBi(MoO4 ) ceramic showed a distorted scheelite structure and a very low sintering
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