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

Author(s)

Bradtmueller, Henrik ^[1] ; Nieto-Munoz, Adriana M. ^[2] ; Ortiz-Mosquera, Jairo F. ^[2] ; Rodrigues, Ana C. M. ^[2] ; Eckert, Hellmut ^{[1, 3]}

Affiliation

^[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

• Document type: Journal article
• Source: Journal of Non-Crystalline Solids; v. 489, p. 91-101, JUN 1 2018.
• Web of Science Citations: 4

Abstract

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 Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC