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Gammond, Lawrence V. D. ^[1] ; Auer, Henry ^[2] ; Da Silva, Rita Mendes ^[1] ; Zeidler, Anita ^[1] ; Ortiz-Mosquera, Jairo F. ^[3] ; Nieto-Munoz, Adriana M. ^[3] ; Rodrigues, Ana Candida M. ^[4] ; Almeida Silva, Igor D'Anciaes ^[5] ; Eckert, Hellmut ^{[6, 5]} ; Benmore, Chris J. ^[7] ; Salmon, Philip S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Bath, Dept Phys, Bath BA2 7AY, Avon - England

^[2] Fraunhofer Inst Ceram Technol & Syst IKTS, Winterbergstr 28, D-01277 Dresden - Germany

^[3] Univ Fed Sao Carlos, Programa Posgrad Cincia & Engn Mat, CP 676, BR-13565905 Sao Carlos, SP - Brazil

^[4] Univ Fed Sao Carlos, Dept Engn Mat, CP 676, BR-13565905 Sao Carlos, SP - Brazil

^[5] Univ Sao Paulo, Inst Fis Sao Carlos, CP 369, BR-13566590 Sao Carlos, SP - Brazil

^[6] WWU Munster, Inst Phys Chem, Corrensstr 30, D-48149 Munster - Germany

^[7] Argonne Natl Lab, Xray Sci Div, Adv Photon Source, 9700 South Cass Ave, Lemont, IL 60439 - USA

• Tipo de documento: Artigo Científico
• Fonte: Journal of Chemical Physics; v. 155, n. 7 AUG 21 2021.
• Citações Web of Science: 0

Resumo

The structure of crystalline and amorphous materials in the sodium (Na) super-ionic conductor system Na1+xAlxGe2-x(PO4)(3) with x = 0, 0.4, and 0.8 was investigated by combining (i) neutron and x-ray powder diffraction and pair-distribution function analysis with (ii) Al-27 and P-31 magic angle spinning (MAS) and P-31/Na-23 double-resonance nuclear magnetic resonance (NMR) spectroscopy. A Rietveld analysis of the powder diffraction patterns shows that the x = 0 and x = 0.4 compositions crystallize into space group-type R3, whereas the x = 0.8 composition crystallizes into space group-type R3c. For the as-prepared glass, the pair-distribution functions and Al-27 MAS NMR spectra show the formation of sub-octahedral Ge and Al centered units, which leads to the creation of non-bridging oxygen (NBO) atoms. The influence of these atoms on the ion mobility is discussed. When the as-prepared glass is relaxed by thermal annealing, there is an increase in the Ge and Al coordination numbers that leads to a decrease in the fraction of NBO atoms. A model is proposed for the x = 0 glass in which super-structural units containing octahedral Ge-(6) and tetrahedral P-(3) motifs are embedded in a matrix of tetrahedral Ge-(4) units, where superscripts denote the number of bridging oxygen atoms. The super-structural units can grow in size by a reaction in which NBO atoms on the P-(3) motifs are used to convert Ge-(4) to Ge-(6) units. The resultant P-(4) motifs thereby provide the nucleation sites for crystal growth via a homogeneous nucleation mechanism. Published under an exclusive license by AIP Publishing. (AU)

• Processo FAPESP: 17/17800-0 - Estudo de correlações estrutura/propriedade em vidros e vitrocerâmicas para armazenamento de energia por técnicas de RMN de estado sólido.
• Beneficiário: Igor d'Anciães Almeida Silva
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 13/07793-6 - CeRTEV - Centro de Pesquisa, Tecnologia e Educação em Materiais Vítreos
• Beneficiário: Edgar Dutra Zanotto
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs