caa a22 4500 467927855 CHVBK 20180406152934.0 cr unu---uuuuu 170328e20061101xx s 000 0 eng 10.1134/S0020168506110173 doi (NATIONALLICENCE)springer-10.1134/S0020168506110173 Quantum-chemical modeling of titanium centers in titanosilicate glass [Elektronische Daten] [V. Sokolov, V. Plotnichenko, E. Dianov] Quantum-chemical simulation of cluster models for a number of titanium centers in titanosilicate glasses has been performed with GAMESS software within the local-density-functional approach, using the BLYP functional, which is known to ensure the best agreement with experimentally determined vibrational frequencies. For each center, we have determined its equilibrium configuration, vibrational frequencies, infrared absorption intensities, and the intensity and degree of depolarization of Raman bands. The results indicate that the totally polarized Raman band near 1030 cm−1 is due to single four-coordinate Ti atoms, whereas the partially polarized Raman band near 940 cm−1 is contributed by both single (totally depolarized Raman scattering) and double (partially polarized Raman scattering) four-coordinate Ti centers, which accounts for the fact that the relative intensities of these bands depend on TiO2 concentration. We also show that negatively charged four-coordinate Ti atoms can only be formed through electron excitation, in particular, optical excitation, and that hopping transport of electrons between neutral and negatively charged four-coordinate Ti atoms may be responsible for optical losses of up to 10 dB/km, which should be considered the minimum theoretical level of losses in titanosilicate glasses. The so-called Ti3+ centers may be both six-and three-coordinate Ti atoms, but not four-coordinate. Pleiades Publishing, Inc., 2006 Sokolov V. Fiber Optics Research Center, Prokhorov General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, 119991, Moscow, Russia aut Plotnichenko V. Fiber Optics Research Center, Prokhorov General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, 119991, Moscow, Russia aut Dianov E. Fiber Optics Research Center, Prokhorov General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, 119991, Moscow, Russia aut Inorganic Materials Nauka/Interperiodica 42/11(2006-11-01), 1273-1288 0020-1685 42:11<1273 2006 42 10789 https://doi.org/10.1134/S0020168506110173 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1134/S0020168506110173 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sokolov V. Fiber Optics Research Center, Prokhorov General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, 119991, Moscow, Russia aut NATIONALLICENCE 700 1- Plotnichenko V. Fiber Optics Research Center, Prokhorov General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, 119991, Moscow, Russia aut NATIONALLICENCE 700 1- Dianov E. Fiber Optics Research Center, Prokhorov General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, 119991, Moscow, Russia aut NATIONALLICENCE 773 0- Inorganic Materials Nauka/Interperiodica 42/11(2006-11-01), 1273-1288 0020-1685 42:11<1273 2006 42 10789 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer