Annotation of the articleThe Raman spectra application in studies of the structural units ordering in the cation sublattice and the photîrefractive properties of lithium niobate single crystals of dissimilar compositions, i. e. nominally pure ones with varying Li/Nb ratios and crystals alloyed with nonphotorefractive cations, Gd3+ and Y3+ is discussed. It is shown that at small, Gd3+ and Y3+ concentrations the photo refractive effect value is essentially controlled by the structural units ordering in the cation sublattice. It is found that the line intensity corresponding to bridge valent vibrations of oxygen atoms in NbO6 octahedra is sensitive to the cation sublattice dipole ordering. |