Raman and infrared structural investigation of xRb(2)O center dot(1-x)GeO2 glasses
Φόρτωση...
Ημερομηνία
Συγγραφείς
Kamitsos, E. I.
Yiannopoulos, Y. D.
Karakassides, M. A.
Chryssikos, G. D.
Jain, H.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
American Chemical Society
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Journal of Physical Chemistry
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
Infrared reflectance and Raman spectra of rubidium germanate glasses, xRb(2)O .(1 - x)GeO2, have been measured and studied as a function of Rb2O mole fraction in the range 0 less than or equal to x less than or equal to 0.60. The spectra of corresponding crystalline germanate phases, GeO2-quartz, GeO2-rutile, Rb2Ge4O9, K4Ge9O20, K2Ge2O5, and K2GeO3, have been also measured for a better understanding of the glass spectra. At very low content (x less than or equal to 0.01) Rb2O was found to induce a redistribution of GeO4 tetrahedra in rings smaller than those encountered in quartz- and glassy GeO2. The spectral manifestations of this trend are the frequency increase of the Raman active symmetric stretching vibration of Ge-O-Ge bridges and the parallel decrease of the infrared frequency of the asymmetric stretching of Ge-O-Ge bridges, Beyond the composition x = 0.01 and up to x approximate to 0.15-0.20, the predominant modification mechanism involves the transformation of GeO4 tetrahedra into GeO6 octahedra, with characteristic Raman scattering at 315, 590, and 630 cm(-1). At higher alkali content and up to the limits of glass formation, tetrahedral Q(n) species with nonbridging oxygens are formed ((4 - n) is the number of nonbridging oxygens per tetrahedron). Thus, Q(3) appears beyond x = 0.10, giving place to Q(2) (x > 0.30), Q(1) (x > 0.50), and Q(0) (x = 0.60). The characteristic Raman bands of these germanate tetrahedra were measured at 865, 765, 740, and 720 cm(-1), respectively, Based on semiempirical models, the spectroscopic results were quantified to yield the average coordination number of Ge atoms, as well as the fraction of Ge atoms in 6-fold coordination. Both were found to exhibit a maximum value at approximately 15 mol % Rb2O.
Περιγραφή
Λέξεις-κλειδιά
alkali germanate glasses, x-ray-diffraction, vibrational spectroscopy, reflectance spectra, na2o-geo2 glasses, silicate-glasses, borate glasses, vitreous geo2, coordination, absorption
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://A1996UW68500036
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Μηχανικών Επιστήμης Υλικών