VIBRATIONAL STUDIES OF AMORPHOUS AND CRYSTALLINE SbSBr

Author Institution:The $A_{v}B_{vi}C_{vii}$ family of ferroelectric materials includes the highly colored species SbSBr and SbSI which may be prepared in both crystalline and amorphous phases. A vibrational study of crystalline and glassy SbSBr has been attempted utilizing both Raman and infrared spectroscopy. The far-ir spectrum of the paraelectric phase of crystalline SbSBr has been recorded as well as the room temperature spectrum of the glass. Furthermore, evidence which strongly suggests a thermochromic phase change at $\sim 90^{\circ} C$ has been gathered from Raman spectra of crystalline SbSBr over the temperature range of $20^{\circ} - 160^{\circ} C$

SPECTROSCOPIC STUDIES OF CATION VIBRATION IN OXIDE GLASSES

Author Institution:Binary metal oxide glasses having the metaphosphate composition have been prepared containing cations from the following groups: alkali metals, alkaline earths, transition metals, and lanthanide and actinide metals. Far infrared absorption assigned the cation vibration in its oxygen cage has been measured for these glasses. Empirical ionic models are proposed correlating the absorption maximum with the cation mass and its charge, or the mass and its ionic radius. Discrepancies between the observed and predicted vibrational frequency indicate a more covalent interaction between the metal cation and the glass network. Raman intensities and vibrational frequencies of the network metaphosphate vibrations have been obtained and provide additional evidence about the cation-site interaction

SPECTROSCOPIC INVESTIGATION OF GLASS TRANSITIONS, STRUCTURE, AND CATION VIBRATIONS IN INORGANIC OXIDE GLASSES

Author Institution: Department of Chemistry, Brown UniversityFar infrared ($10-800 cm^{-1}$) spectra of metal-polymetaphosphate glasses having the compositions $M_{2}O \cdot P_{2}O_{5}$ or $MO\cdot P_{2}O_{5}$ reveal broad, low frequency cation-motion bands, whose frequencies and half-bandwidths vary inversely with cation mass. The bands shift to lower frequencies as the $M_{2}O$ or MO mole-fraction of a given glass is decreased. Force field elements for the alkali cation-network vibrations, calculated assuming the cation local environment to be an $O_{h}$ oxygen field, vary linearly with the glass transition temperature of the stoichiometric glasses. Comparison between the spectra for the glassy and crystalline forms of alkali metaphosphates indicates that the observed cation-dependent bands in the glass spectra results from strong damping of analogous crystalline modes. Interionic vibrations are also observed for metaborate and metagermanate glasses and for mixed alkali glasses. The Raman spectra of drawn glass fibers from the phosphate, borate, and germanate glass forming systems yield information relating to the glass molecular structure, through measurement of the fiber-orientation angular dependence of the polarization of the Raman bands. High temperature Raman spectroscopy is employed to follow glass to crystal phase transitions in alkali metaphosphate glasses