Detailed Raman scattering measurements were performed on molybdenum-sulfur-iodine nanowires (Mo 6 S 3 I 6 ). At room temperature, 21 well-resolved Raman modes were experimentally observed for the first time in this new compound. The phase stability and vibrational properties of the nanowires were investigated by different temperature treatments. High-temperature Raman spectra showed that the phase separation of Mo 6 S 3 I 6 nanowires took place between 573 and 673 K, followed by appearance of a new mode at 819 cm −1 characteristic of the MoO 3 phase. Low-temperature Raman scattering spectra showed a significant difference in phonon-phonon interactions between internal and external Raman modes of Mo 6 S 3 I 6 nanowires. These interesting vibrational properties can give new insights for improved material preparation and achievement of higher conductivity and other functional properties of these otherwise interesting materials.

Ultrafine pure and cobalt doped SnO2-? nanocrystals (Sn1-xCoxO2-?, 0 ? x ? 0.05) were synthesized by microwave-assisted hydrothermal method. The as-prepared nanocrystals have single phase tetragonal rutile structure. With increase of Co content (x > 0.01), Co entered into SnO2 lattice in mixed Co2+/Co3+ state. Pronounced blue shift of the band gap with cobalt doping originated from the combined effect of quantum confinement and Burnstain-Moss shift. Raman and photoluminescence study revealed oxygen deficient structure of SnO2-? for which the prevalent defects are in the form of in-plane oxygen vacancies. Co-doping induced decrease of in-plane oxygen vacancy concentration and luminescence quenching. SnO2-? exhibited significantly better photocatalytic activity under UV light irradiation, than Co-doped samples due to better UV light absorption and increased concentration of in-plane oxygen vacancies which, as shallow donors, enable better electron-hole separation and faster charge transport. [Project of the Serbian Ministry of Education, Science and Technological Development]

Abstract. We have measured the far-infrared reflectivity spectra of the sodium vanadium oxide η-Na1.3V2O5 polycrystals in the wide temperature (80-300 K) and frequency (150-1500 cm −1 ) range. Appearance of new phonon oscillators, phonon oscillator mode splitting and step-like shift of TO and LO frequencies at low temperatures are correlated with the charge-ordering phase transition, which takes place at about 120 K in this vanadium oxide. PACS