Synthesis, structure and properties of layered Pr 2 MoO 6 -based oxymolybdates doped with Mg.

Undoped and Mg-doped Pr ₂ MoO ₆ oxymolybdate polycrystals and single crystals have been prepared by solid-state reactions and flux growth. The compounds have been characterized by powder X-ray diffraction, energy-dispersive spectroscopy, inductively coupled plasma mass spectrometry, scanning transmission electron microscopy, single crystal X-ray structure analysis, differential scanning calorimetry and thermogravimetry. The (MgO) _x (Pr ₂ O ₃ ) _y (MoO ₃ ) _z (x + y + z = 1) solid solution series has been shown to extend to x = 0.03. The structure of the Mg-doped Pr ₂ MoO ₆ single crystals can be represented as superimposed lattices of the main matrix (Pr ₂ MoO ₆ ) and lattices in which Mo atoms are partially replaced by Mg. The incorporation of Mg atoms into the structure of Pr ₂ MoO ₆ results in the disordering of the praseodymium and oxygen lattices. Both the polycrystalline and single-crystal Mg-doped samples are hygroscopic.