High temperature and composition induced phase transitions in LiZnV<inf>1-x</inf>As<inf>x</inf>O<inf>4</inf> phenacites: Crystal structure and Raman spectroscopy studies

B. Manoun, M. Azrour, P. Lazor, M. Azdouz, L. Bih, S. Benmokhtar, Rachid Essehli, L. El Ammari

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Abstract

Abstract In this work, using techniques of X-ray diffraction and Raman spectroscopy, we report the composition and high-temperature induced phase transition in the system LiZnV<inf>1-</inf><inf>x</inf>As<inf>x</inf>O<inf>4</inf> (0 ≤ x ≤ 1). Both techniques showed that the increase of arsenic amount induced a structural transition from R-3 LiZnVO<inf>4</inf> type to LiZnAsO<inf>4</inf> type belonging to R3 space group, the transition occurring between x = 0.7 and x = 0.8. Furthermore, increasing temperature for the compositions (0.8 ≤ x ≤ 1) manifests a transition from the LiZnAsO<inf>4</inf> structural type with R3 space group to the R-3 LiZnVO<inf>4</inf> structural type. For this series, the transition from the space group R3 to the centro-symmetric space group R-3 shows considerable changes in the compositional and temperature dependencies of the bands: spectral positions of all the observed Raman bands exhibit shifts linearly proportional to the temperature increase, with points of shift-rate changes revealing a symmetry change. The Raman-spectra based temperature-composition phase diagram confirms the results obtained using the method of Rietveld refinements, thus showing the R-3 to R3 transition occurring between x = 0.7 and 0.8.

Original languageEnglish
Article number13919
Pages (from-to)956-964
Number of pages9
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Volume151
DOIs
Publication statusPublished - 16 Jul 2015

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Keywords

  • High temperature Raman spectroscopy
  • LiZnV<inf>1-</inf><inf>x</inf>As<inf>x</inf>O<inf>4</inf>
  • Phase transition
  • Phenacite structure
  • Rietveld refinements
  • X-ray diffraction

ASJC Scopus subject areas

  • Instrumentation
  • Atomic and Molecular Physics, and Optics
  • Analytical Chemistry
  • Spectroscopy

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