Structural, thermal and electrical studies of thallium-scandium-hafnium(zirconium) molybdates

https://doi.org/10.1016/j.jssc.2021.122832

Thallium scandium hafnium molybdate Tl5ScHf(MoO4)6 and thallium scandium zirconium molybdate Tl5ScZr(MoO4)6 crystallize in trigonal symmetry with the space group R3¯c. The compounds are synthesized by sintering the finely powdered simple molybdates mixture in a muffle furnace at 723–823 K for 100 h. The crystal structures of Tl5ScHf(MoO4)6 and Tl5ScZr(MoO4)6 are obtained by Rietveld method. The following unit cell parameters are calculated for Tl5ScHf(MoO4)6: a = 10.62338 (5), c = 38.0579 (2) Å, V = 3719.64 (4) Å3, Z = 6 and for Tl5ScZr(MoO4)6: a = 10.63216 (7), c = 38.0716 (3) Å, V = 3727.14 (5) Å3, Z = 6. The conductivity of the Tl5ScHf(MoO4)6 and Tl5ScZr(MoO4)6 are measured between 293 and 860 K. The ionic conductivity of Tl5ScHf(MoO4)6 and Tl5ScZr(MoO4)6 molybdates are 8 × 10−4 S/cm and 8 × 10−3 S/cm (at 773 K); the activation energy of ionic transfer are 0.8 eV and 0.3 eV respectively.