Synthesis, crystal structure, and electrical and magnetic properties of Ce3MoO7

Powder samples and single crystals of the ternary oxide Ce3MoO7 were obtained by solid state reaction. The structure was determined by single-crystal X-ray diffraction. Ce3MoO7 crystallizes in the orthorhombic space group P212121 (no. 19) with unit-cell parameters a=7.5395(2) Å, b=7.6769(1) Å, c=10.9769(2) Å and Z=4. Full-matrix least-squares refinement on F2 using 3903 independent reflections for 101 refinable parameters results in R1=0.0281 and wR2=0.0473. The structure consists of chains of corner-linked MoO6 octahedra running parallel to the b-axis and separated from each other by seven- or eight-coordinate Ce–O polyhedra. The trend of the unit-cell parameters of the Ln3MoO7 series, plotted versus the R3+ ionic radius, shows a linear behavior, which strongly suggests a trivalent state for the Ce atoms. Magnetic susceptibility measurements confirm that the oxidation state of the Ce atoms is +3. Resistivity measurements on a single crystal show that the Ce3MoO7 compound is a semi-conductor with a band gap of about 2 eV.