High-Temperature Salt Flux Crystal Growth of New Lanthanide Molybdenum Oxides, Ln(5)Mo(2)O(12) Ln = Eu, Tb, Dy, Ho, and Er: Magnetic Coupling within Mixed Valent Mo(IV/V) Rutile-Like Chains

摘要

Five new lanthanide molybdenum oxides containing mixed valent Mo(IV/V) rutile-like chains, Ln(5)Mo(2)O(12) Ln = Eu, Tb, Dy, Ho, and Er, were prepared utilizing a high-temperature molten salt flux synthesis involving an in situ reduction utilizing metallic reducing agents. All five compounds were structurally characterized by single-crystal and powder X-ray diffraction methods and were found to crystallize in the monoclinic space group C2/m. The molybdates all contain rare infinite chains consisting of MoO2O4/2 edge-sharing octahedra. The chains exhibit alternating long and short separations between octahedra caused by the presence of Mo Mo bonds to form Mo2O18 units containing one unpaired electron. The temperature dependence of the magnetic susceptibility of these compounds was measured, and antiferromagnetic ordering was observed in all cases.