YVO₄ single crystals (yttrium orthovanadate) are interesting materials for laser and optical application. The pure YVO₄ single crystal (crystallized in D_4h¹⁹ - I 4₁/amd space group) can be used for making polarizers, beam displacers and optical isolators due to its large birefringence (n_e – n_o = 0.223 at 1.06 mm). Compared with the YAG laser crystals, the Nd-doped YVO₄ crystal has a low pumping threshold, large emission section (2.7 times at 1.06 mm), large absorption coefficient (4 times), wide absorptive area at 809 nm and strongly polarized laser output and low susceptibility to gamma and electron irradiations. It is an excellent material for making the diode-pumped solid lasers.

The influence of neodymum doping of YVO₄ single crystals has been studied. These crystals have been grown by means of Czochralski method. One of them has been pure YVO₄, others have been doped with the Nd (YVO₄:1% at. Nd, YVO₄:2% at. Nd and YVO₄:5% at. Tm+0.4%Ca).

The precise changes of the lattice parameters were determined by the X-ray diffraction method – the Bond method (δd/d =10^-6). The lattice parameters was measured on symmetric reflections 800 and 008 CuKα₁, λ=0.15405929 ± 5×10^-7. We have observed increase of the lattice parameters with the increasing concentration of Nd atoms and slighty changes of the unit cell volume. These changes are connected with site location of the atom dopants in YVO₄ crystal structure.