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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.)

Glass-to-crystal transition in the NASICON glass-ceramic system Na1+xAlxM2-x(PO4)(3) (M = Ge, Ti)

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Bradtmueller, Henrik [1] ; Nieto-Munoz, Adriana M. [2] ; Ortiz-Mosquera, Jairo F. [2] ; Rodrigues, Ana C. M. [2] ; Eckert, Hellmut [1, 3]
Total Authors: 5
[1] WWU Munster, Inst Phys Chem, Corrensstr 30, D-48149 Munster - Germany
[2] Univ Fed Sao Carlos, Dept Engn Mat, CP 676, BR-13565905 Sao Carlos, SP - Brazil
[3] Univ Sao Paulo, Inst Fis Sao Carlos, CP 369, BR-13566590 Sao Carlos, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Journal of Non-Crystalline Solids; v. 489, p. 91-101, JUN 1 2018.
Web of Science Citations: 3

The glass-to-crystal transition of Na1+xAlxGe2-x(PO4)(3) (NAGP), and Na1+xAlxTi2-x(PO4)(3) (NATP), both crystallizing in variants of the Na-superionic conducting (NASICON) structure, has been investigated by solid-state NMR. The ceramic materials produced by annealing the precursor glasses above the glass transition temperature are candidate materials for solid-state separator membranes in sodium ion batteries. The different local structural environments involving both network former and network modifier species have been characterized by comprehensive Na-23, Al-27 and P-31 magic angle spinning nuclear magnetic resonance (MAS NMR) experiments. In crystalline Na1+xAlxGe2-x(PO4)(3) samples multiple phosphate environments are observed, corresponding to n Al and 4-n Ge species in their second coordination spheres. In contrast, no site resolution is observed in the analogous Na1+xAlxTi2-x(PO4)(3) system. This can be understood on the basis of X-ray powder diffraction (XRD) data, which reveal a significant lattice expansion in the former, but no lattice expansion in the latter material. Al-27 MAS-NMR data reveal that in the glassy state, Al occurs with coordination numbers four, five and six, with the fraction of four-coordinated Al being substantially higher in the NATP glasses than in the NAGP glasses. Na-23 MAS-NMR and spin echo decay measurements reveal distinct differences between glassy and crystallized materials with regard to the local environments and the spatial distributions of the sodium ions. (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