The Russian scientists managed to get CRYSTAL 30mm size and good optical quality, which has been successfully will be used in the laser.
Russian chemists, researchers learned how to grow crystals of the complex oxide composition Y2Be2SiO7, a promising material for optoelectronics, which can also be used as a crystalline medium for laser crystals.
?Oxide crystals doped with chromium ions (Cr4 +), are interesting as the active medium for tunable in the near-infrared region of the spectrum (1.3-1.5 m), and how to work on the effect of the saturable absorption passive valves one-micrometer lasers. Therefore, to activate the Cr4 + ions are optimal crystalline environment in the crystal structure which contains an item with tetrahedral coordination |, say the authors of the development - Kutovyi SA, Kuz#39;micheva GM, VL Panyutin and A. Oleynik
?Well-known today Cr4 +-doped laser media are forsterite Mg2SiO4 and garnet Y3Al5O12, the structures of which, along with tetrahedral contains octahedral sites, which includes chromium ions readily with the usual formal charge Cr3 +. The content of the Cr4 + crystals are usually very low. For example, in a total content garnets chromium ~ 1% at. typical concentration of tetrahedrally coordinated Cr4 + are only a hundredth of the concentration of Cr3 +, occupying octahedral sites. |
Researchers have developed a method for preparing a composition of the oxide Y2Be2SiO7, crystallizing in the structure of the family of melilite, which was obtained by the Czochralski method, similar to other complex oxide - skandoboratu lanthanum, which determines the possibility of industrial production of crystals with a diameter of 15 mm and a length of 30 mm of good optical quality crystal growth vessel 3 at the following conditions: nitrogen-oxygen atmosphere cultivation - N2/O2 relative volume concentration of 98/2 (vol.%); 40x2x40 mm iridium crucible, the melt surface temperature about 1650 | C; priming - iridium rod, the drawing speed 1 ,5-3 mm / h speed shaft 10 rev / min, the growth chamber insulation - ceramic Al2O3, ZrO2.
Earlier, in previous studies [SF Vartram CRYSTAL strusture ° F Y 2 Be 2 SiO 7. / / Sristallograrhisa Asta, V. 1969, v.25, p. 791-795] has already been described ways of getting Y2Be2SiO7. Then polycrystalline samples Y2Be2SiO7, were synthesized in air at +1350 | C. for 100 hours, of stoichiometric amounts of oxides of yttrium, silicon and beryllium, previously pressed into a tablet. The obtained single crystals of size 0,15 x0, 15h0, 2 mm were obtained by gas transport SiO2 on the surface of the rod BeO-Y2O3 Globar furnace, in which bricks are used as the insulator of SiO2.
But these polycrystalline samples and single crystals of such a small size that can not be used as a medium for laser crystals.
Therefore, the researchers set out to develop a method for obtaining v large complex oxide composition Y2Be2SiO7, crystallizing in the structure of the family of melilite.
SUMMARY Russian researchers developed method consists in the fact that as starting materials for the complex oxide of formula Y2Be2SiO7 used high-purity oxide powders of yttrium, silicon and beryllium in a weight ratio of the following: yttria - 76,21-67,22% silica - 17 ,89-12, 98% beryllium oxide - remaining content up to 100%. After mixing powders of high purity, the mixture was compressed into tablets of 30 mm diameter. Tablets themselves calcined in a muffle furnace at a temperature +1195-1205 | C for 19-20 hours, after which they were placed in a crucible and melted crystal is grown from a melt surface temperature +1645-1655 | C Czochralski method.
Thus, the scientists were able to obtain crystals with a diameter of 15 mm and a length of 30 mm of good optical quality, which determines the possibility of industrial production of these crystals and their use as a crystalline medium for laser crystals.
Contact information:
109507, Moscow, ul. Fergana, 28/7, kv.262, GM Kuz#39;micheva
