Structural studies on W 6+ and Nd 3+ substituted La2Mo2O9 materials

D Marrero–Lopez, J Canales–Vazquez, Wuzong Zhou, John Thomas Sirr Irvine, P Nunez

Research output: Contribution to journalArticlepeer-review

70 Citations (Scopus)

Abstract

The structure of a series of new ionic conductors based in lanthanum molybdate (La2Mo2O9) has been investigated using transmission electron microscopy (TEM), high-resolution X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The superstructure 2a(c) x 3a(c) x 4a(c) of the low temperature alpha-polymorph relative to the beta-polymorph was confirmed by HRTEM imaging and electron diffraction. Furthermore, the effects of partial cation substitution in the La2-xNdxMo2O9 and La(2)Mo(2-y)WyO(9) series have been also evaluated in the search of new clues to understand the structure and stabilisation of the high temperature and better conductor beta-polymorph. The thermal analysis studies show that Nd-substitution does not stabilise completely the beta-polymorph at room temperature, although no superstructure ordering was observed by both XRD and HRTEM. On the other hand, W-substitution stabilises the cubic flpolymorph for y > 0.25, although, electron diffraction indicates a slight distortion from the cubic symmetry for low W-content. This distortion disappears as the W content increases and the Rietveld refinements gradually render better results. (c) 2005 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)278-288
Number of pages11
JournalJournal of Solid State Chemistry
Volume179
DOIs
Publication statusPublished - Jan 2006

Keywords

  • La2Mo2O9
  • ionic conductor
  • HRTEM
  • superstructure
  • phase transition
  • OXIDE-ION CONDUCTORS
  • TRANSPORT-PROPERTIES
  • ELECTRICAL-CONDUCTIVITY
  • CRYSTAL-STRUCTURE
  • LAMOX FAMILY
  • GD
  • ELECTROLYTES
  • RELAXATION
  • STABILITY
  • DIFFUSION

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