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  • Author or Editor: R. Lanjewar x
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Abstract  

Mössbauer spectra of hexakis (trimethylacetato) ferrate(III) complexes with general formula M3[Fe{OCOC(CH3)3}6] (where M=H+, Li+, Na+, K+ and NH 4 + ) exhibit a quadrupole doublet with EQ=0.31–0.65 mms–1 and =0.60–0.74 mms–1 (with respect to S.N.P. as standard). Infrared studies suggest unidentate coordination of the carboxylate ligands. Anomalously high and EQ values for H3[Fe{OCOC(CH3)3}6] have been explained in terms of possible hydrogen bonding. Thermal decomposition studies show fast and single stage decomposition yielding a constant weight at 320°C. Mössbauer spectra of intermediates after heating complexes at different temperatures indicate increasing EQ values. At 350°C, all complexes exhibit six-line spectra, suggesting the formation of alkali metal ferrate (Na2O·NaFeO2) or Fe2O3.

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Abstract  

A series of carboxylatoferrate (III) complexes have been synthesized with monocarboxylic and dicarboxylic acids. Mössbauer spectra of all the complexes exhibit quadrupole doublets with EQ=0.36–0.88 mm s–1, suggesting a distorted octahedral geometry. The complexes start decomposing at 100°C and finally yield a constant weight at <500°C. Mössbauer spectral studies of the intermediates and final products after heating at different temperatures yield a complex pattern, suggesting the formation of one or two magnetic phases. Mössbauer spectra of the final products show two, six or eight lines with a central doublet, all indicating the formation of -Fe2O3 of different particle sizes. It is proposed that decarboxylation occurs first, followed by the loss of one or two ligands, depending on the nature of the carboxylate and the heating tempeature. The complex of pyridine-2,6-dicarboxylic acid shows an anomalous behavior.

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Abstract  

Fast neutron-activation methods have been developed for the determination of iron and silicon in USGS and Indian standards and bauxites. Nuclear reactions56Fe/n, p/56Mn and28Si/n, p/28Al were carried out using241Am-Be neutron source and cutting off thermal neutrons with a Cd shield. For Si a cyclic method was adopted due to short half life of28Al /2.3 min/. The methods are non destructive, fast, economic and ideal for bulk analysis of rocks and process control.

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Abstract  

A radiochemical method for the determination of gold using198Au, has been developed. It is based on the synergistic extraction of Au(III) with thionalide (TA) in ethyl methyl ketone (EMK) or isobuthyl methyl ketone (IBMK) at pH 5.0.Effect of various parameters such as pH, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 25 ng of Au.

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Abstract  

A radiochemical solvent extraction method has been developed for the micro determination of Mo/VI/ using99Mo tracer. It involves removal of99mTc by ethyl methyl ketone /EMK/ and extraction of Mo with tri-n-butyl phosphate /TBP/ from 5M HCl. Different parameters affecting the extraction such as pH dependence, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 2 g of Mo.

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Abstract  

Mössbauer and infrared spectroscopic studies of a series of iron(III) complexes of dicarboxylic acids, maleic, malonic, succinic, glutaric, adipic, pimelic, suberic, azealic and sebacic have been carried out at room temperature. All complexes exhibit a quadrupole doublet with isomer shift () values in the range of 0.62 –0.72 mm·s–1 (with respect to SNP) and quadrupole splitting, EQ=0.53–0.74 mm· s–1. It is observed that tris complexes are formed up to pimelic acid, while bis complexes are formed those for the other three acids. Isomer shift () values do not vary significantly but EQ values show a somewhat regular trend. Magnetic moment data indicate high spin Fe(III) in octahedral geometry.

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Abstract  

The thermal behaviour of substituted pentacyanoferrates(II) of the type Na3[Fe(CN5)L]·xH2O, whereL=n-, sec-, tert- oriso-butylamine,di-iso-butylamine ortri-n-butylamine, was investigated with the aid of Mössbauer spectroscopy, XRD and TG-DTG-DTA. The Mössbauer spectra of these complexes exhibit a quadrupole doublet with ΔE Q=0.70−0.83 mm s−1 at room temperature. The isomer shift, δ=0.00±0.03 mm s−1 suggests that the iron atom is in the +2 low-spin state. The complexes start to decompose at 50°C, yielding a residual mass of 5.8 –21.3% in the temperature range 900–950°C. The Mössbauer spectra recorded after heating at 150 and 300°C exhibit an asymmetric doublet, suggesting partial decomposition. The Mössbauer spectra at higher temperature are complex. At different stages of the thermal process, the presence of α-Fe2O3, γ-Fe2O3, α-Fe, Fe3C and Fe3O4 was demonstrated.

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