Fe II-III (oxy)hydroxycarbonate green rusts; from ferri- to ferromagnetism
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Fe II-III (oxy)hydroxycarbonate green rusts; from ferri- to ferromagnetism J.-M. R. Génin et al. Institut Jean Barriol Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS- Université Henri Poincaré-Nancy 1, Département Matériaux et Structures, ESSTIN, 405 rue de Vandoeuvre, F-54600 Villers-lès-Nancy, France. E-Mail:[email protected] “Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
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Fe II-III (oxy)hydroxycarbonate green rusts; from ferri- to ferromagnetism J.-M. R. Génin et al. Institut Jean Barriol Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS- Université Henri Poincaré-Nancy 1, Département Matériaux et Structures, ESSTIN, - PowerPoint PPT Presentation
Transcript of Fe II-III (oxy)hydroxycarbonate green rusts; from ferri- to ferromagnetism
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Gtlich, Bill, Trautwein: Mssbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009
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FeII-III hydroxysalts green rusts, which are layered double hydroxides (LDH), are constituted of [FeII(1-x) FeIIIx (OH)2 ]x+ layers and [(x/n)An- (mx/n)H2O]x- interlayers that can incorporate various anions such as Cl-, CO32-, SO42-, HCOO-, C2O42-, SeO42- For Chloride GR1(Cl-):[FeII2FeIII(OH)6]+[Cl-2H2O]- Sulphate GR2(SO42-): [FeII4FeIII2(OH)12]2+[SO42-8H2O]2- Carbonate GR1(CO32-):[FeII4FeIII2(OH)12]2+[CO32-3H2O]2-There exist two types of space groups as determined by XRD: GR1 [R(-3)m] and GR2 [P(-3)m1] that depend on the shape of the anion. Mssbauer spectra display 2 ferrous doublets D1 & D2 (large D) and1 ferric doublet D3 (small D).
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For GR1(CO32-): a = 0.317588(2) nm and c = 2.27123(3) nm
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The in situ oxidation of green rusts by deprotonationUse a strong oxidant such as H2O2, Dry the green rust and oxide in the air, Violent air oxidation, Oxide in a basic medium
FeII6(1-x) FeIII6x O12 H2(7-3x) CO3FeII-III oxyhydroxycarbonate0 < x < 1Gtlich, Bill, Trautwein: Mssbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009
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Evolution of Mssbauer spectra with measurement temperature displaying the ferrimagnetic behaviour of stoichiometric GR(CO32-) between 1.4 and 12 K.FeII4 FeIII2 (OH)12 CO3 ferrimagnetism
H = 130 kOeD = -3 mm s-1(a)1.4 KMssbauer spectra of GR(CO32-) sample oxidised violently by H2O2 and named ferric [GR(CO32-)*]1. Measurement temperatures are (a) 16 K, (c) 50 K, (d) 60 K and (e) 78 K. (b) and (f) are the hyperfine field distribution of (a) and quadrupole splitting distribution of (e) using a Voigt profile analysis, respectively.FeIII6 O12 H8 CO3 ferromagnetismGtlich, Bill, Trautwein: Mssbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009
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Projections perpendicular to the c axis of a Fe layer with octahedrons of OH- ions that can be deprotonated or protonated for values of x = 0, 0.33, 0.67 and 1. There exist four ordered types of domain to match any intermediate composition as determined by x.
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Hexagonal pavements of FeII and FeIII cations in the layers of (a) Fe(OH)2, (b) stoichiometric GR(CO32-) at x = 1/3, (c) GR(CO32-)* with 1/3 < x < 2/3, (d) GR(CO32-)* at x = 2/3, (e) GR(CO32-)* with 2/3 < x < 1 and (f) fully ferric GR(CO32-)* at x = 1. Long range order is displayed showing magnetic domains.
