Rietveld refinements and vibrational spectroscopic studies of Na 1-xKxPb4(PO4)3 lacunar apatites (0≤x≤1)

M. Azrour, M. Azdouz, B. Manoun, R. Essehli, S. Benmokhtar, L. Bih, L. El Ammari, A. Ezzahi, A. Ider, A. Ait Hou

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Synthesis of apatites, Na1-xKxPb4(PO 4)3 0≤x≤1, with anion vacancy was carried out using solid state reactions. The solid solution of apatite-type structure crystallizes in the hexagonal system, space group P63/m (No 176). Rietveld refinements showed that 75% of Pb2 cations are located in the (6h) sites; the ninefold coordination sites (4f) are equally occupied by the other 25% lead cations and the K and Na monovalent ions. The structure can be described as built up from [PO4]3- tetrahedra and Pb 2 of sixfold coordination cavities (6h positions), which delimit void hexagonal tunnels running along [0 0 1]. These tunnels are connected by cations of mixed sites (4f) half occupied by Pb2 and half by Na/K mixed cations. The assignment of the observed frequencies in the Raman and infrared spectra is discussed on the basis of a unit cell group analysis and by comparison with other apatites. The Raman modes of all the compositions show some linear shifts of the frequencies as a function of the composition toward lower values due the substitutions of Na by K with a larger radius.

Original languageEnglish
Pages (from-to)1199-1205
Number of pages7
JournalJournal of Physics and Chemistry of Solids
Volume72
Issue number11
DOIs
StatePublished - Nov 2011
Externally publishedYes

Funding

The authors are grateful to 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
Vetenskapsrådet

    Keywords

    • C. Raman and infrared spectroscopies
    • C. X-ray diffraction

    Fingerprint

    Dive into the research topics of 'Rietveld refinements and vibrational spectroscopic studies of Na 1-xKxPb4(PO4)3 lacunar apatites (0≤x≤1)'. Together they form a unique fingerprint.

    Cite this