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Fe{sub 2}(AsO{sub 4})F: A new three-dimensional condensed fluoro-arsenate iron(II) compound with antiferromagnetic interactions

Journal Article · · Journal of Solid State Chemistry
 [1];  [2];  [1];  [1];  [1];  [2]
  1. Departamento de Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Apdo. 644, E-48080 Bilbao (Spain)
  2. Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Apdo. 644, E-48080 Bilbao (Spain)
Fe{sub 2}(AsO{sub 4})F has been synthesized under mild hydrothermal conditions in the form of single crystals. The compound crystallizes in C2/c monoclinic space group with the unit cell parameters a=13.214(1), b=6.623(1), c=10.045(1)A and {beta}=116.90(2) deg. with Z=8. The crystal structure consists of a three-dimensional framework constructed by two kinds of chains, A and B, with 50% of population. In the chains, the environments for the iron(II) cations show penta- and hexa-coordination. The chains establish an angle of approximately 120 deg. between them. The disordered fluoride anions in these chains given rise to [Fe(1)O{sub 4}F(1){sub 0.5}(F(2){sub 0.5}){sub 2}] and [Fe(2)O{sub 4}(F(1){sub 0.5}){sub 2}F(2){sub 0.5}] edge-shared polyhedra in which the fluoride anions have occupancy factors of 50% over two distinct crystallographic sites. The IR spectrum shows the characteristic bands of the (AsO{sub 4}){sup 3-} groups. From the diffuse reflectance spectrum a D{sub q} parameter of 650cm{sup -1} has been calculated for the Fe(II) d{sup 6} high spin cation. The Mossbauer spectrum in the paramagnetic state shows a doublet that has been fitted, according to the existence of two crystallographically independent iron environments, with two Lorentzian doublets. Magnetic measurements performed between room temperature and 5K exhibit a maximum at 22.6K, characteristic of antiferromagnetic interactions with a estimated 'J'-exchange parameter of -1.2K.
OSTI ID:
20905296
Journal Information:
Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 6 Vol. 179; ISSN 0022-4596; ISSN JSSCBI
Country of Publication:
United States
Language:
English