Electron paramagnetic resonance (EPR) spectra of sodium-germanate glasses (xGeO(2) . (1 - x)Na2O, 0.65 < x < 1) prepared by the conventional melting technique are analyzed as a function of the Na2O content, before and after X-ray irradiation. Signals due to three-fold coordinated Ge sites (Ge E' centers) and non-bridging oxygen hole centers (NBOHCs) are observed, whereas no signal due to paramagnetic centers related to GeO6 sites is detected. At high Na2O concentration, a broad signal at g = 2.21 is also observed. The EPR results suggest three main mechanisms for the Na+ ion insertion: interstitial; network modifier; a source of medium range structural rearrangements of GeO4 tetrahedra. (C) 2000 Elsevier Science B.V. All rights reserved.
Azzoni, C., DI MARTINO, D., Paleari, A., Almeida, R. (2000). Paramagnetic sites in alkali germanate glasses. JOURNAL OF NON-CRYSTALLINE SOLIDS, 278(1-3), 19-23 [10.1016/S0022-3093(00)00347-1].
Paramagnetic sites in alkali germanate glasses
DI MARTINO, DANIELA;PALEARI, ALBERTO MARIA FELICE;
2000
Abstract
Electron paramagnetic resonance (EPR) spectra of sodium-germanate glasses (xGeO(2) . (1 - x)Na2O, 0.65 < x < 1) prepared by the conventional melting technique are analyzed as a function of the Na2O content, before and after X-ray irradiation. Signals due to three-fold coordinated Ge sites (Ge E' centers) and non-bridging oxygen hole centers (NBOHCs) are observed, whereas no signal due to paramagnetic centers related to GeO6 sites is detected. At high Na2O concentration, a broad signal at g = 2.21 is also observed. The EPR results suggest three main mechanisms for the Na+ ion insertion: interstitial; network modifier; a source of medium range structural rearrangements of GeO4 tetrahedra. (C) 2000 Elsevier Science B.V. All rights reserved.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
