Synthesis, characterization and thermal study of RbU(IV)MoO and RbU(VI)MoO systems

•Synthesis of novel quaternary rubidium uranium (IV) molybdates by solid state route.•XRD analysis of the compounds.•Thermal stability in helium atmosphere and oxidation in air using TG/DTG/DTA technique.•Phase diagram of RbUMoO system at 873 K.

Four novel rubidium uranium (IV) molybdate compounds, Rb4U5(MoO4)12, Rb2U(MoO4)3, Rb4U(MoO4)4 and Rb8U(MoO4)6 have been prepared by solid state route, reacting Rb2MoO4, UMoO5 and MoO3 in desired molar proportions in evacuated sealed quartz ampoules at 823 K and characterized by powder X-ray diffraction (XRD) and thermal analysis techniques. Thermal stability of the compounds was determined in helium atmosphere and oxidation behavior was studied in air using Thermogravimetric (TG) technique. The sub-solidus phase relations in RbU(VI)MoO system were determined at 873 K in air. A pseudo-ternary phase diagram of Rb2OUO3MoO3 system was drawn on the basis of phase analysis of various phase mixtures prepared in RbUMoO system and phase fields were established by powder X-ray diffraction. Rb2UMo2O10, Rb6UMo4O18 and Rb2U2Mo3O16 were identified during phase diagram study. Melting and thermal stability of these compounds were determined using differential thermal analysis (DTA) technique.