765207-04-3Relevant articles and documents
Thermoanalytical study of iron(III) phosphate obtained by homogeneous precipitation from different media
Scaccia, Silvera,Carewska, Maria,Prosini, Pier Paolo
, p. 81 - 86 (2004)
Amorphous iron(III) phosphate has been synthesised by homogeneous precipitation from equimolecular Fe(NH4)2(SO 4)2·6H2O and NH4H 2PO4 aqueous, water-ethanol and water-iso-propanol solutions at pH=2.0 and ambient temperature using hydrogen peroxide as precipitating agent. The precipitates have been characterised by TG/DTG/DTA techniques, chemical analysis, X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM). The presence of ethanol and iso-propanol in the precipitation medium suppressed the co-precipitation of ferric sulphate as it does in aqueous medium. Thermal treatment of the as-precipitates at 750°C in air yields a crystalline quartz-like structured FePO4 with markedly different morphological features.
Crystal growth, single-crystal structure refinement and unusual ligand-field splittings of lazulite-type oxidephosphates MTi2O 2(PO4)I (M = FeII, CoII, Ni II)
Schoeneborn,Glaum
, p. 2568 - 2578 (2007)
Single crystals of oxidephosphates MTi2O2(PO 4)2 [M: Fe (dark red), Co (pinkish red), Ni (green)] with edge-lengths up to 0.4 mm were grown by chemical vapour transport. FeTi 2O2(PO4)2 and CoTi2O 2(PO4)2 are isotypic to NiTi2O 2(PO4)2. The crystal structure of the latter was previously solved from powder data [FeTi2O2(PO 4)2 (data for CoTi2O2(PO 4)2 and NiTi2O2(PO4) 2 in brackets): monoclinic, P21/c, Z = 2, a = 7.394(3) (7.381(6), 7.388(4)) A, b = 7.396(2) (7.371(5), 7.334(10))A, c = 7.401(3) (7.366(6), 7.340(3)) A, β = 120.20(3) (120.26(6), 120.12(4))°, R1 = 0.0393 (0.0309, 0.0539) wR2 = 0.1154 (0.0740, 0.1389), 2160 (1059, 1564) independent reflections, 75 (76, 77) variables]. The single-crystal study allowed improved refinement using anisotropic displacement parameters, yielded lower standard deviations for the structural parameters and revealed a small amount of cation disordering. Twinning and cation disordering within the structures are rationalized by a detailed crystallographic classification of the MTi2O 2(PO4)2 structure type in terms of group-subgroup relations. The structure is characterized by a three-dimensional network of [PO4] tetrahedra and [MIITi2O 12] groups formed by face-sharing of [MIIO6] and [TiO6] octahedra. Electronic absorption spectra of MTi 2O2(PO4)2 in the UV/VIS/NIR region show rather large ligandfield splittings for the strongly trigonally distorted chromophors [MIIO6] (M = Fe, Co, Ni) with interelectronic repulsion parameters beeing slightly smaller than in other phosphates. Interpretation of the spectra within the framework of the angular overlap model reveals a significant second-sphere ligand field effect of TiIV ions on the electronic levels of the NiII and CoII.
Thermal stability of the soil minerals destinezite and diadochite Fe 3+2(PO4)(SO4)(OH)·6H 2O - Implications for soils in bush fires
Frost, Ray L.,Palmer, Sara J.
, p. 121 - 124 (2011/10/03)
Thermogravimetry combined with evolved gas mass spectrometry has been used to ascertain the stability of the soil minerals destinezite and diadochite Fe3+2(PO4)(SO4)(OH)·6H 2O. These two minerals are identical except for their morphology. Diadochite is amorphous whereas destinezite is crystalline. Both minerals are found in soils. It is important to understand the stability of these minerals because soils are subject to bush fires especially in Australia. The thermal analysis patterns of the two minerals are similar but not identical. Subtle differences are observed in the DTG patterns. For destinezite, two DTG peaks are observed at 129 and 182 °C attributed to the loss of hydration water, whereas only a broad peak with maximum at 84 °C is observed for diadochite. Higher temperature mass losses at 685 °C for destinezite and 655 °C for diadochite, are due to sulphate decomposition, based upon the ion current curves. This research has shown that at low temperatures the minerals are stable but at high temperatures, as might be experienced in a severe bush fire, the minerals decompose.
A new layered organically templated iron(II) phosphite, (C 2H10N2)[Fe3(HPO3) 4]. Hydrothermal synthesis, crystal structure and spectroscopic and magnetic properties
Chung, U-Chan,Mesa, Jose L.,Pizarro, Jose L.,Lezama, Luis,Garitaonandia, Jose S.,Chapman, Jon P.,Arriortua, Maria I.
, p. 2705 - 2713 (2008/10/09)
The (C2H10N2)[Fe3(HPO 3)4] compound has been synthesized by using mild hydrothermal conditions under autogeneous pressure and the ethylenediamine molecule as templating agent. The compound crystallizes in the triclinic P1 space group with unit-cell parameters a=5.416(1), b=5.416(1), c=13.977(2)A, α=80.64(2), β=85.25(1), γ=60.03(1)°and Z=1. The final R-factors were R1=0.053 [wR2=0.092]. The crystal structure is constructed of layers stacked along the c-axis. The sheets contain FeO6 octahedra linked by (HPO3)2- phosphite oxoanions to give rise to Fe3O12 trimeric units sharing faces. The IR spectrum shows the characteristic bands of the phosphite and ethylenediammonium ions. From the diffuse reflectance spectrum, the Dq parameter of 805cm-1 has been calculated for the iron(II) cation in slightly distorted octahedral geometry. The Moessbauer spectrum exhibits two doublets characteristic of two crystallographically independent iron(II) ions in octahedral symmetry. Magnetic measurements indicate the existence of antiferromagnetic interactions.
