New compounds Li3Ba2Bi3(XO4)8 (X = Mo, W): synthesis and properties

Abstract

New compounds Li3Ba2Bi3(XO4)8(Х = Mo, W) were obtained by the ceramic technology. Those are the first representatives of the ternary molybdates and tungstates Li3Ba2Bi3(XO4)8 family, which contain different from the rare earth elements trivalent metal. The sequence of chemical transformations occurring during the Li3Ba2Bi3(WO4)8 formation has been established. The primary characterization of the obtained phases was carried out and their ion-conducting properties were studied. The synthesized compounds are shown to melt incongruently, isostructural to the lanthanide-containing analogues (structural type of BaNd2(MoO4)4, sp. gr. C2/c) and crystallize in the monoclinic crystal system with unit cell parameters а = 5.2798(1), b = 12.8976(4), c = 19.2272(5) Å, b = 90.978(2)° (Х = Mo), а = 5.2733(2), b = 12.9032(4), c = 19.2650(6) Å, b = 91.512(3)° (Х = W). Li3Ba2Bi3(XO4)8 are found to undergo the diffuse first-order phase transitions at 441°C (molybdate) and 527°C (tungstate), after that their conductivity reaches values of 10–3–10–4 S/cm.

Keywords

• triple molybdates and tungstates
• solid-state synthesis
• powder x-ray diffraction study
• thermal properties
• ionic conductivity