Structural and Morphological Features of Single Crystals of Cd1–xZnxWO4 Solid Solutions

The results of studying the structural and morphological features of single crystals of Cd _1--x ZnxWO4 solid solutions with a wolframite structure, grown by spontaneous crystallization, are presented. The crystals form a continuous series of single-phase substitutional solid solutions in the Zn/Cd cation sublattice. The crystal growth forms and their sequence with changes in the Zn/Cd ratio were defined. Using X-ray diffraction analysis, the unit cell parameters were determined, and the structure of Cd _1--x ZnxWO4 crystals was refined for a number of their compositions. It was found that the dependences of the parameters a and c correspond to Vegard’s linear law, while the dependence of the parameter b deviates from it. In crystals of mixed cationic composition (Cd _1--x Znx)2+, a redistribution of electron density was revealed near tungsten atoms, indicating their structural disorder. For crystals of different composition, the coordination polyhedra WO6 and (Cd _1--x /Znх)O6 were characterized, and their arrangement in the structure relative to the main crystallographic directions was studied. The structural features of the crystals were compared with their Raman spectra. The types of possible structural disorder in the crystals were characterized.