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Reactivity and Structural Defects in Glaserite‐Type Iron‐Vanadates
Author(s) -
Reuß Anna,
Ksenofontov Vadim,
Tapp Joshua,
Möller Angela
Publication year - 2018
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201800360
Subject(s) - redox , reactivity (psychology) , formula unit , chemistry , ionic radius , rietveld refinement , crystallography , ion , crystal structure , inorganic chemistry , medicine , alternative medicine , organic chemistry , pathology
We investigated (a) the redox reaction of FeO and Ag 2 O in the presence of BaCO 3 and V 2 O 5 under inert atmosphere and (b) the oxidation of FeO in air in the presence of BaCO 3 , Na 2 CO 3 , and V 2 O 5 . The reaction products are members of the glaserite‐type of compounds: Ba(Ag□)Fe[VO 4 ] 2 [ a = 5.47397(4) Å, c = 7.1780(1) Å, P 3 ]; BaNa 1.63 Fe 0.79 [VO 4 ] 2 [ a = 9.672(1) Å, b = 5.5860(6) Å, c = 14.1505(4) Å, β = 90.042(9)°, C 2/ c ]; and Ba(Ba,Na)Na[VO 4 ] 2 [ a = 5.8478(2) Å, c = 7.3835(3) Å, P 3 m 1]. The latter presents an example for a statistical distribution of differently charged ions with differences in ionic radii (Ba 2+ and Na + ) on the B site of the general formula AB 2 M [VO 4 ] 2 . The iron compounds exhibit differences in the defect concentration and localization of voids. For Ba(Ag□)Fe[VO 4 ] 2 the Fe 3+ ‐triangular lattice remains intact and the Ag substructure is depleted by 50 % through the redox reaction (a). In contrast, for BaNa 1.63 Fe 0.79 [VO 4 ] 2 defects occur on both sites ( B = Na + and M = Fe 3+ ) with a total of 0.58 defects per formula unit. Extended 57 Fe‐Mössbauer studies on a series of Fe‐glaserite compounds relate structural findings from Rietveld refinements of X‐ray diffraction data with defect concentrations, substitution variants, and charge distributions.