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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Monitoring crystallization in lithium silicate glass-ceramics using Li-7 -> Si-29 cross-polarization NMR

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Schroeder, Cornelia [1] ; Carlos Villas-Boas, Mariana de Oliveira [2] ; Serbena, Francisco C. [3] ; Zanotto, Edgar D. [2] ; Eckert, Hellmut [4, 1]
Total Authors: 5
[1] WWU Munster, Inst Phys Chem, D-48149 Munster - Germany
[2] Univ Fed Sao Carlos, Lab Mat Vitreous LaMaV, BR-13565905 Sao Carlos, SP - Brazil
[3] Univ Estadual Ponta Grossa, Dept Fis & Astron, BR-84030900 Ponta Grossa, PR - Brazil
[4] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13566590 Sao Carlos, SP - Brazil
Total Affiliations: 4
Document type: Journal article
Source: Journal of Non-Crystalline Solids; v. 405, p. 163-169, DEC 1 2014.
Web of Science Citations: 2

Quantification of the crystalline versus amorphous fraction is an important objective for the structural characterization of glass-ceramics. Owing to its well-documented ability of differentiating between crystalline and amorphous materials and its inherently quantitative character, magic-angle-spinning solid state nuclear magnetic resonance (MAS-NMR) spectroscopy is an excellent method for this objective. For the technologically important lithium disilicate glass-ceramics, the applicability of Si-29 MAS-NMR is, however, seriously impeded by poor signal to noise ratios and extremely long spin-lattice relaxation times (on the order of magnitude of hours). The detection sensitivity problem can be overcome by magnetization transfer from Li-7 nuclei to the Si-29 spins (Li-7 -> Si-29 cross-polarization). While this method is inherently non-quantitative owing to the influence of various relaxation processes involved, we show that it can be successfully calibrated to yield quantitatively reliable crystalline fractions that are similar to those determined by alternative methods (optical microscopy and X-ray powder diffraction). In addition, this method can be used to detect very low (similar to 1%) crystallized volume fractions. (C) 2014 Elsevier B.V. All rights reserved. (AU)

FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
Grantee:Edgar Dutra Zanotto
Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC