Characterisation of scheelite LaW0.16Nb0.84O4.08 ion conductor by combined synchrotron techniques: Structure, W oxidation state and interdiffusion

JOURNAL OF ALLOYS AND COMPOUNDS

卷:857

Article

Canu, Giovanna¹  Giannici, Francesco²  Chiara, Alessandro²  Confalonieri, Giorgia³  Longo, Alessandro^4,5  Buscaglia, Maria Teresa¹  Dapiaggi, Monica⁶  Buscaglia, Vincenzo¹  Martorana, Antonino² 

[1] CNR ICMATE Inst Condensed Matter Chem & Technol E, Via De Marini 6, I-16149 Genoa, Italy

[2] Univ Palermo, Dipartimento Fis & Chim Emilio Segre, Viale Sci, I-90128 Palermo, Italy

[3] Univ Modena & Reggio Emilia, Dipartimento Sci Chim & Geol DSCG, Via Giuseppe Campi 103, I-41125 Modena, Italy

[4] ISMN CNR Ist Studio Mat Nanostrutturati, Via Ugo La Malfa 153, I-90146 Palermo, Italy

[5] European Synchrotron Radiat Facil, 71 Ave Martyrs, F-38000 Grenoble, France

[6] Univ Milan, Dipartimento Sci Terra, Via Botticelli 23, I-20133 Milan, Italy

关键词: Scheelite;    Electrolyte;    Solid-oxide fuel cells;    XANES;    LSM;    Chemical compatibility;   

DOI  :  10.1016/j.jallcom.2020.157532

来源: Elsevier

【 摘 要 】

Scheelite-type materials such as LaNbO4 are increasingly attracting attention as a possible alternative to the most common fluorite and perovskite structure as ion conductors. However, they are much less used and investigated. The introduction of tungsten in lanthanum orthoniobate leads to conduction properties that are compatible with oxygen ion conductivity. In this paper, we studied the effect of the introduction of tungsten in the LaNbO4 structure. High resolution X-ray diffraction showed that in LaNb1-xWxO4+x/2 with x = 0.16 the monoclinic distortion is largely suppressed and the tetragonal phase is predominant at room temperature. By XANES/EXAFS we proved that tungsten is in its 6+ valence state and no W5+ was detected. With X-ray microspectroscopy, we studied in detail with a submicrometre-probe the interdiffusion and degradation processes taking place between the material and LSM, a common electrode material, during their long-term contact at high temperatures. (C) 2020 Elsevier B.V. All rights reserved.

【 授权许可】

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