Z. B. Perekalina

Structure and some physical properties of K2Ni(SO4)2 ⋅ 6H2O crystals

The data obtained from the analysis of the solubility phase diagrams have been used in growth of K2Ni(SO4)2 ⋅ 6H2O crystals. The X-ray diffraction studies of the crystals grown showed that, at room temperature, the crystals belong to the diffraction class 2/m. The crystal structure is similar to the structures of the Tutton salts. The study of the absorption spectra and the differential scanning calorimetry (DSC) revealed a pronounced anomaly in the vicinity of 45–46°C, which seems to be associated with the structural changes in the crystal.

Spectroscopy studies of pure and chromium-doped calcium gallogermanate crystals, Ca3Ga2Ge4O14

Absorption spectra, the spectra of circular dichroism and magnetic circular dichroism of pure and Cr-doped Ca3Ga2Ge4O14 crystals have been studied. The crystal-field parameters and the transition frequencies of Cr3+ ions are calculated. The location of Cr3+ and Cr4+ ions in oxygen octahedra and tetrahedra is confirmed. The spectra of circular dichroism show the maxima due to Cr3+ ions and growth-induced defects.

Anisotropic optical properties of crystals with the Ca-gallogermanate structure

The optical properties of inactivated and activated crystals with the structure of Ca-gallogermanate have been studied. The components of the gyration pseudotensor for Sr3Ga2Ge4O14 crystals are determined. In the ultraviolet range of the spectra of all the crystals studied, the bands of circular and linear dichroism and the anomalous behavior of the linear birefringence are observed irrespective of the activating dopant. The formation of these bands is not associated with the electron transitions of doping ions and can be caused by structural defects formed in the growth process.

Influence of X-ray irradiation on the optical properties of chromium-doped KliSO4 crystals

The absorption and circular-dichroism spectra of chromium-activated KLiSO4 crystals both nonirradiated and irradiated with an X-ray beam have been studied. It was established that in nonirradiated crystals chromium ions are mainly trivalent (Cr3+) and have octahedral coordination. In irradiated crystals, along with the centers provided by (Cr3+) ions, new centers are formed associated with (Cr4+) and (Cr5+) ions.

Circular dichroism of uniaxial sulfate crystals in the range of electronic transitions of sulfate groups

Absorption and circular-dichroism spectra of uniaxial inactivated sulfate crystals KLiSO4 and [C2H4(NH2) · H2SO4] have low-intensity bands in the spectral range of 0.20–0.35 μm. These bands are attributed to forbidden transitions in a sulfate group.

Absorption spectra and circular dichroism of Sr3Ga2Ge2O14: Cr and Ca3Ga2Ge2O14: Cr crystals

Absorption spectra and circular dichroism spectra of chromium-doped Sr-gallogermanate crystals of different colors and doped and pure Ca-gallogermanate crystals have been studied. It is shown that chromium ions enter the Sr-gallogermanate crystals in two valence states—Cr3+ and Cr4+. It is assumed that Cr4+ ions replace Ge4+ in the tetrahedra.