Synthesis, crystal structure, and electrical properties of the new ternary molybdate Rb5NdHf(MoO4)6

The subsolidus phase relations in the ternary salt system Rb2MoO4-Nd2(MoO4)3-Hf(MoO4)2 were studied by X-ray powder diffraction. The ternary molybdates Rb5NdHf(MoO4)6 (1) and Rb2NdHf2(MoO4)6.5 are formed in this system. Compound 1 without impurities was synthesized by the solid-phase method by varying the temperature in the range of 400–600 °C and the annealing time from 70 to 110 h. Single crystals of compound 1 were grown by the flux method. The structure of compound 1 was established and the electrical properties of ceramic samples of this compound were investigated. This ternary molybdate has mixed electronic-ionic conductivity with the ionic component predominating at 200–500 °C.