TY - JOUR
T1 - Mixed valence states in cobalt iron cyanide
AU - Martínez-García, R.
AU - Knobel, M.
AU - Balmaseda, J.
AU - Yee-Madeira, H.
AU - Reguera, E.
PY - 2007/2
Y1 - 2007/2
N2 - Cobalt iron cyanide with both Co and Fe in mixed valence states were prepared and characterized. In this mixed valence system the cobalt atom is found both as high spin Co(2+) and low spin Co(III) while iron always appears in low spin state to form two solid solutions: Co(2+)Co(III) hexacyanoferrates (II,III), and Co(2+)Co(III) hexacyanoferrate (II). Such solid solutions have the following formula units: (Co2+)x(CoIII)1-xK[(FeII)1-x(FeIII)x(CN)6]·frac(1, 2)H2O and (Co2+)1.5x(CoIII)1-xK[FeII(CN)6]·yH2O (0 ≤ x ≤ 1, 1 ≤ y ≤ 14). Compounds within these two series were characterized from Infrared, Mössbauer, X-ray diffraction and thermo-gravimetric data, and magnetic measurements at low temperature. A model for their crystal structure is proposed and the structure for a representative composition refined from XRD powder patterns using the Rietveld method. A simple and reproducible procedure to prepare these solid solutions is provided. Within hexacyanoferrates, such mixed valence states system in both metal centres shows unique features, which are discussed from the obtained data.
AB - Cobalt iron cyanide with both Co and Fe in mixed valence states were prepared and characterized. In this mixed valence system the cobalt atom is found both as high spin Co(2+) and low spin Co(III) while iron always appears in low spin state to form two solid solutions: Co(2+)Co(III) hexacyanoferrates (II,III), and Co(2+)Co(III) hexacyanoferrate (II). Such solid solutions have the following formula units: (Co2+)x(CoIII)1-xK[(FeII)1-x(FeIII)x(CN)6]·frac(1, 2)H2O and (Co2+)1.5x(CoIII)1-xK[FeII(CN)6]·yH2O (0 ≤ x ≤ 1, 1 ≤ y ≤ 14). Compounds within these two series were characterized from Infrared, Mössbauer, X-ray diffraction and thermo-gravimetric data, and magnetic measurements at low temperature. A model for their crystal structure is proposed and the structure for a representative composition refined from XRD powder patterns using the Rietveld method. A simple and reproducible procedure to prepare these solid solutions is provided. Within hexacyanoferrates, such mixed valence states system in both metal centres shows unique features, which are discussed from the obtained data.
KW - A. Magnetic materials
KW - C. Mössbauer spectroscopy
KW - D. Crystal structure
KW - D. Electronic structure
KW - D. Magnetic properties
UR - http://www.scopus.com/inward/record.url?scp=33846620118&partnerID=8YFLogxK
U2 - 10.1016/j.jpcs.2006.11.008
DO - 10.1016/j.jpcs.2006.11.008
M3 - Artículo
SN - 0022-3697
VL - 68
SP - 290
EP - 298
JO - Journal of Physics and Chemistry of Solids
JF - Journal of Physics and Chemistry of Solids
IS - 2
ER -