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MAS NMR AND SEM STUDY OF LOCAL STRUCTURE CHANGES INDUCED BY HEAT TREATMENT IN La2B4Al2O12

M. Vasilescu1, G. Borodi1, S. Simon1,*

Affiliation

  1. Babes-Bolyai University, Faculty of Physics, 3400 Cluj-Napoca, Romania

Abstract

Xerogels of composition La2B4Al2O12, treated between 200 and 1100C, are investigated by magic angle spinning nuclear magnetic resonance (MAS NMR) and scanning electron microscopy (SEM). The 11B MAS NMR results indicate the presence of tetra coordinated boron in all investigated samples. For three coordinated boron, two sites were observed one of them being present only after heat treatment above 860 C when the sample become crystalline. The mean values of the NMR parameters like chemical shift, asymmetry parameter and quadrupolar coupling constant are strongly influenced by the heat treatment temperature. SEM results are correlated with them obtained by NMR..

Keywords

MAS NMR, SEM, Xerogels, Porous materials.

Submitted at: July 22, 2002
Accepted at: March 12, 2003

Citation

M. Vasilescu, G. Borodi, S. Simon, MAS NMR AND SEM STUDY OF LOCAL STRUCTURE CHANGES INDUCED BY HEAT TREATMENT IN La2B4Al2O12, Journal of Optoelectronics and Advanced Materials Vol. 5, Iss. 1, pp. 153-156 (2003)