CRYSTAL STRUCTURE OF BINARY MOLYBDATE Pr<sub>2</sub>Hf<sub>3</sub>(MoO<sub>4</sub>)<sub>9 </sub>
Crystals of binary praseodymium and hafnium molybdate of Pr<sub>2</sub>Hf<sub>3</sub>(MoO<sub>4</sub>)<sub>9</sub> composition are grown by solution-melt crystallization under spontaneous nucleation conditions. By the X-ray diffraction data (X8 Apex automated diffractometer, Мо<i>K</i><sub>α</sub> radiation, 2262 <i>F</i>(<i>hkl</i>), <i>R</i> = 0.0170) its composition and crystal structure are determined. Parameters of the trigonal unit cell are: <i>a</i> = <i>b</i> = 9.8001(1) Å, <i>c</i> = 58.7095(8) Å, <i>V</i> = 4883.15(10) Å<sup>3</sup>, <i>Z</i> = 6, space group <i>Rc</i>. The crystal structure is composed of three types of polyhedra: МоО<sub>4 </sub>tetrahedra, HfO<sub>6</sub> octahedra, and nine-vertex PrO<sub>9</sub>. All three types of polyhedra are bonded among themselves by common oxygen vertices of bridging МоО<sub>4</sub> tetrahedra forming an openwork three-dimensional structure.