High temperature and composition induced phase transitions in LiZnV1-xAsxO4 phenacites: Crystal structure and Raman spectroscopy studies

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

Research output: Contribution to journalArticlepeer-review

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 LiZnV1-xAsxO4 (0 ≤ x ≤ 1). Both techniques showed that the increase of arsenic amount induced a structural transition from R-3 LiZnVO4 type to LiZnAsO4 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 LiZnAsO4 structural type with R3 space group to the R-3 LiZnVO4 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
StatePublished - Jul 16 2015
Externally publishedYes

Funding

The authors are grateful to the University Hassan 1st, the Swedish Research Council and the Swedish International Development Co-operation Agency ( Sida ) for the financial grant (MENA) offered in support of this work.

FundersFunder number
MENA
Swedish International Development Co-operation Agency
Styrelsen för Internationellt Utvecklingssamarbete
Vetenskapsrådet

    Keywords

    • High temperature Raman spectroscopy
    • LiZnVAsO
    • Phase transition
    • Phenacite structure
    • Rietveld refinements
    • X-ray diffraction

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