Structure and Properties of <i>Ln</i><sub>2</sub>MoO<sub>6</sub> Oxymolybdates (<i>Ln</i> = La, Pr, Nd) Doped with Magnesium
Ekaterina Orlova,
Elena Kharitonova,
Timofei Sorokin,
Alexander Antipin,
Nataliya Novikova,
Nataliya Sorokina,
Valentina Voronkova
Affiliations
Ekaterina Orlova
Faculty of Physics, Moscow State University, Moscow 119991, Russia
Elena Kharitonova
Faculty of Physics, Moscow State University, Moscow 119991, Russia
Timofei Sorokin
Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, Moscow 119333, Russia
Alexander Antipin
Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, Moscow 119333, Russia
Nataliya Novikova
Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, Moscow 119333, Russia
Nataliya Sorokina
Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, Moscow 119333, Russia
Valentina Voronkova
Faculty of Physics, Moscow State University, Moscow 119991, Russia
The literature data and the results obtained by the authors on the study of the structure and properties of a series of polycrystalline and single-crystal samples of pure and Mg-doped oxymolybdates Ln2MoO6 (Ln = La, Pr, Nd) are analyzed. Presumably, the high-temperature phase I41/acd of Nd2MoO6 single crystals is retained at room temperature. The reason for the loss of the center of symmetry in the structures of La2MoO6 and Pr2MoO6 and the transition to the space group I4¯c2 is the displacement of oxygen atoms along the twofold diagonal axes. In all structures, Mg cations are localized near the positions of the Mo atoms, and the splitting of the positions of the atoms of rare-earth elements is found. Thermogravimetric studies, as well as infrared spectroscopy data for hydrated samples of Ln2MoO6 (Ln = La, Pr, Nd), pure and with an impurity of Mg, confirm their hygroscopic properties.