The crystallographic and magnetic characteristics of Sr{sub 2}CrO{sub 4} (K{sub 2}NiF{sub 4}-type) and Sr{sub 10}(CrO{sub 4}){sub 6}F{sub 2} (apatite-type)

Journal Article · Tue May 15 04:00:00 EDT 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.02.023· OSTI ID:21015806

Baikie, Tom ^[1]; Ahmad, Zahara ^[1]; Srinivasan, Madhavi ^[1]; Maignan, Antoine ^[2]; Pramana, Stevin S ^[1]; White, T J ^[1]

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1. Division of Materials Science, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore)
2. Laboratoire CRISMAT, UMR CNRS 6508, ISMRA-ENSICAEN, 6 Boulevard du Marechal Juin, 14050, Caen, Cedex (France)

Solid-state reaction between SrCO{sub 3}, Cr{sub 2}O{sub 3} and SrF{sub 2} has produced the apatite phase Sr{sub 10}(CrO{sub 4}){sub 6}F{sub 2} and Sr{sub 2}CrO{sub 4} which adopts the K{sub 2}NiF{sub 4}-type structure. The reaction outcome was very sensitive to the heating rate with rapid rise times favouring the formation of Sr{sub 2}CrO{sub 4}, which has been synthesised at ambient pressure for the first time. Powder X-ray diffraction and electron diffraction confirmed that Sr{sub 2}CrO{sub 4} adopts a body centred tetragonal cell (space group I4/mmm) with lattice parameters a=3.8357(1) A and c=12.7169(1) A, while a combination of neutron and X-ray diffraction verified Sr{sub 10}(CrO{sub 4}){sub 6}F{sub 2} is hexagonal (space group P6{sub 3}/m) with lattice parameters a=9.9570(1) A and c=7.4292(1) A. X-ray photoelectron spectroscopy and magnetic measurements were used to characterise the oxidation states of chromium contained within these phases. - Graphical abstract: A solid-state reaction between SrCO{sub 3}, Cr{sub 2}O{sub 3} and SrF{sub 2} produced Sr{sub 10}(CrO{sub 4}){sub 6}F{sub 2} apatite and Sr{sub 2}CrO{sub 4} which adopts the K{sub 2}NiF{sub 4}-type structure. Powder X-ray and electron diffraction confirmed that Sr{sub 2}CrO{sub 4} is body-centred tetragonal, while a combination of neutron and X-ray diffraction verified Sr{sub 10}(CrO{sub 4}){sub 6}F{sub 2} is hexagonal. X-ray photoelectron spectroscopy and magnetic measurements identified the oxidation states of chromium in these phases.

• OSTI ID: 21015806
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 5 Vol. 180; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
APATITES
CHROMATES
CHROMIUM OXIDES
CRYSTALLOGRAPHY
ELECTRON DIFFRACTION
HEXAGONAL LATTICES
LATTICE PARAMETERS
NEUTRON DIFFRACTION
SPACE GROUPS
STRONTIUM CARBONATES
STRONTIUM FLUORIDES
TETRAGONAL LATTICES
X RADIATION
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY