Safflorite, (Co,Ni,Fe)As2, isomorphous with marcasite
نویسندگان
چکیده
Safflorite, a naturally occurring cobalt-nickel-iron diarsenide (Co,Ni,Fe)As(2), possesses the marcasite-type structure, with cations (M = Co + Ni + Fe) at site symmetry 2/m and As anions at m. The MAs(6) octa-hedra share two edges, forming chains parallel to c. The chemical formula for safflorite should be expressed as (Co,Ni,Fe)As(2), rather than the end-member format CoAs(2), as its structure stabilization requires the simultaneous inter-action of the electronic states of Co, Ni, and Fe with As(2) (2-) dianions.
منابع مشابه
Crystal structure of glaucodot, (Co,Fe)AsS, and its relationships to marcasite and arsenopyrite
The crystal structure of glaucodot, (Co,Fe)AsS, an important member of the FeAsS-CoAsS-NiAsS system, was determined with single-crystal X-ray diffraction. It is orthorhombic with space group Pn21m and unit-cell parameters a = 14.158(1), b = 5.6462(4), c = 3.3196(2) Å, and V = 265.37(5) Å3. The structure is closely related to that of arsenopyrite or alloclasite, and represents a new derivative o...
متن کاملChemical stability and extent of isomorphous substitution in ferrites precipitated under ambient temperatures.
The ferrite process is an established method for treating wastewaters containing dissolved toxic metals, using precipitation at temperatures above 65 °C. Various ambient-temperature operation methodologies have also been proposed, but the effects of temperature reduction on product stability, and on the extent of isomorphous substitution (in terms of x in Me(x)Fe(3-x)O(4), Me representing a non...
متن کاملMarcasite oxidation in low-temperature acidic (pH 3.0) solutions: Mechanism and rate laws
Marcasite surfaces were analyzed using X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES). XPS data of a pristine marcasite surface are used as a template to examine the characteristics of a marcasite surface after exposure to vigorous cleaning procedures and after reaction in oxygenated and mildly acidic (pH 3.0) solution. Minor changes are observed to the Fe(2p3/2) s...
متن کاملPhase Transitions in Crystalline
Solid polymorphism in five compounds of the type [Me(H20)6](BF4)2 , where Me = Mn, Fe, Co, Ni and Zn, have been studied in the temperature range 120 330 K by DSC. For each substance at least three solid modifications have been found. In addition, for compounds with Me = Mn, Fe and Zn some new low temperature phase transitions have been observed. The transition temperatures for the [Me(H20)6](BF...
متن کاملFate of Nickel Ion in (ii-iii) Hydroxysulphate Green Rust Synthesized
In order to investigate the efficiency of sulfate green rust (GR2) to remove Ni from solution, GR2 samples were synthesized under controlled laboratory conditions. Some GR2 samples were synthesized from Fe(II) and Fe(III) sulfate salts by precipitation. Other samples were prepared by coprecipitation, of Ni(II), Fe(II) and Fe(III) sulfate salts, i.e., in the presence of Ni. In another sample, Ni...
متن کامل