ИСТИНА

Oxyhalide glasses are used both as luminescent and laser materials and as precursors to obtain glass-ceramics with a halide crystalline phase. The addition of fluorides or chlorides into the composition of glasses makes it possible to change the properties of glasses over a wide range - to expand the transparency range of glasses, to change the mechanical properties and viscosity of melts. Optical halide materials with a low-frequency phonon spectrum, doped with ions of rare-earth elements, are of great interest for IR applications. The transfer from oxofluoride glasses to oxochloride glasses should a decrease in the phonon energy, an expansion of the transparency range, and the production of luminescence in regions of spectra where this is impossible in oxide and oxofluoride systems. Doping with neodymium makes it possible to obtain luminescence both in the near infrared region and in the middle - at 2.6 and 5.2 microns. Moreover, the last band appears only in media with low-energy phonons, for example, in PbCl2. Lead oxochloride glasses, in contrast to oxofluoride glasses, has been much less studied. Based on a very wide field of vitrification in lead oxofluoride systems, in our work we decided to synthesize glasses based on PbF2-PbO-B2O3 (SiO2) systems by partially replacing PbF2 with PbCl2. Synthesized high-quality glass with a maximum PbCl2 content of 50 mol% in both chloroborate and chlorosilicate systems. In experiments with a higher concentration of PbCl2 in the charge, polycrystalline castings were obtained containing the crystalline phases PbCl2, Pb2OCl2, PbFCl. The absorption spectra of glasses doped with neodymium have all absorption bands typical of Nd. A detailed examination of individual transitions showed that for them the wavelength of the maximum shifts to longer wavelengths with the replacement of fluorine by chlorine. The luminescence spectra also show a shift in the maximum of the transition to longer wavelengths by more than 7 nm. In this case, as the chlorine content increases, the intensity of the long-wavelength components associated with transitions to excited sublevels increases. The shift to longer wavelengths depends on the ratio of the concentrations of lead chloride and fluoride; the larger the proportion of PbCl2, the greater the shift to lon ger wavelengths. The properties of the glasses were modified by heat treatment above the glass transition temperature and by exposure to laser radiation. During the modification, partial crystallization of the glasses is observed. This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation within the FSSM-2020-0005 project.