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  • Author or Editor: V. Garg x
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Abstract  

Mössbauer spectroscopy and X-ray diffractometry have been used to study Sm–Fe mixed oxides (with different SmFe atomic ratios) annealed at 550, 850, 1000 and 1250 °C. The room temperature Mössbauer spectra can be interpreted in terms of one, two or three sextets and in some cases by an additional doublet depending on the composition and the heat treatment. The sextets have been associated with SmFeO3 perovskite, Sm3Fe5O12 garnet and -Fe2O3 hematite. These results are in agreement with those of X-ray diffractometric measurements, which give a clear, evidence of the presence of these phases.

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Abstract  

Solid wastes and sewage sludges in metropolitan cities are potential health hazards due to toxic heavy metal pollutants. Sewage sludges from six Indian cities viz., Ahmedabad, Bikaner, Bombay, Calcutta, Jaipur, Kanpur and solid wastes from six different disposal sites of the capital city of Delhi have been analyzed for 26 elements (As, Au, Ba, Br, Co, Cr, Cs, Cu, Eu, Fe, Hg, Hf, K, La, Mg, Mn, Mo, Na, P, Rb, Sb, Sc, Se, Sr, Th and Zn) by employing instrumental neutron activation analysis (INAA). Sewage sludges from Bombay after different treatments (settled, digested, aerobic, anaerobic) along with several environmental SRMs were also analyzed. An attempt has been made to attribute the pollutant sources to the degree of urbanisation and industrialization of the city. Role of treatment processes in the removal/retention of heavy metals is discussed.

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Abstract  

151Sn Mössbauer spectroscopy was performed with tin triflate Sn(OTf)2 in order to determine its Mösbauer parameters for analytical purposes. The typical Mössbauer parameters at 80 K for crystalline Sn(OTf)2 are IS=4.01±0.02 mm/s and QS=1.20±0.04 mm/s and show that the stannous ion is at a site with less than cubic symmetry under perturbation of the crystal field effect.

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Abstract  

Mössbauer spectroscopy is a useful technique for characterizing the valencies, electronic and magnetic states, coordination symmetries and site occupancies of Fe cations. The Mössbauer parameters of Isomer Shift (I.S.) and Quadrupole Splitting (Q.S.) are useful to distinguish paramagnetic ferrous and ferric ions in several substances, while the internal magnetic field provides information on the crystallinity. A correlation is being sought between Mössbauer parameters and several structure properties of some iron-containing minerals using Artificial Neural Networks (ANN). Distinct regions of crystalline structures are defined when any two parameters are plotted, but in several cases superposition of these regions leads to erroneous conclusions. We have tried to eliminate this difficulty by using convenient axes. These axes form n-dimensional vectors as input to our ANN. In recent years ANN has shown to be a powerful technique to solve problems as pattern recognition, optimization, preview ups and downs in stock market, automatic control and identification of a mineral from a Mössbauer spectrum or Mössbauer data bank. Using ANN we have been successful in identification of crystalline structures from plots of Mössbauer spectral parameters of I.S., Q.S., and structure properties of mean metal-oxygen distance in coordination site. Results using ANN in identification of crystalline structures using Mössbauer parameters of I.S., Q.S., and polyhedral volume of a coordination site are presented.

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Abstract  

Gamma-radiolysis of KNO3 in the matrix of some sulfates, viz. Na2SO4, K2SO4, KNaSO4, KNaSO4: Eu, KNaSO4: Ce, K3Na(SO4)2, K3Na(SO4)2: Eu and K3Na(SO4)2: Ce has been studied at an absorbed dose of 30 kGy.G(NO 2 ) values calculated on the basis of electron fraction in all the sulfates are enhanced significantly. It is also affected by the nature of outer cation and the dopant lanthanide. Electron spin resonance (ESR) and thermoluminescence (TL) measurements show the formation of radical species SO 4 , SO 3 , O 3 , O 2 upon -irradiation. It is proposed that there radical species may transfer energy and interact with the radical species of nitrate (NO 3 2– , NO2, NO3 etc.) so as to enhance the decomposition. A possible mechanism has been proposed.

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Abstract  

The application of Mössbauer spectroscopy, X-ray diffractometry, thermogravimetric analysis and PIXE in the characterization of the particulate matter in atmospheric aerosols in Metropolitan Region of Vitória (MRV), Brazil have been investigated. The main sources of particulate matter, natural, industrial and antropogenic from human activities, have been studied to identify its contribution in the atmospheric particles. During the years 1995 to 1999 samples of total suspended particles (TSP, Ø 100 m) were collected from four points within MRV. The inhalable particles (PM10 Ø 10 m) and sedimented particles (SP) were also collected from the same region. A receptor modeling was used for the identification of the source of particulate matter in the collected urban aerosol.

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Summary  

Eight different brands of Trifala and its three constituents, Amalaki (Embilica officinalis), Bibhitaki (Terminalia bellirica) and Haritaki (T.chebula) were analyzed for 6 minor (Na, K, Mg, Ca, Cl and P) and 19 trace (Al, Ba, Br, Co, Cr, Cs, Fe, Eu, Hf, Hg, La, Mn, Rb, Sb, Sc, Se, Th, V and Zn) elements by instrumental neutron activation analysis (INAA). Two candidate reference materials Tea Leaves (TL-1) and Mixed Polish Herbs (MPH-2) were also analyzed as a part of Intercomparison Study besides several reference materials (RMs) for quality control. The samples along with RMs were irradiated with thermal neutrons in APSARA/Dhruva reactors at BARC, Mumbai and their activity measured on HPGe detector and 8K MCA system. Also Ni, Cu, Cd and Pb contents were determined by AAS. Bibhitaki is found to be enriched in Fe (0.98 mg/g), P (1.10 mg/g), Co (1.74 mg/g) and Se (240 ng/g) including alkali and alkaline earth metals. Availability of many nutrient elements such as Mg, Ca, K, Fe, and Se in Trifala is attributed to its usefulness in the treatment of liver disorder, heart ailments, hepatic diseases and cancer, as expectorant, powerful eye rejuvenator and an antioxidant.

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Summary  

Twenty bhasmas based on Ca, Fe, Zn, Hg, Ag, K, As, Cu, Sn and gemstones have been analyzed for main constituent elements along with minor (Na, K, Mg, Ca, P), trace (Cr, Mn, Fe, Co, Cu, Zn, Hg) and toxic elements by instrumental neutron activation analysis (INAA) including their C, H, N and S contents. Siddhamakaradhwaja, an Hg preparation and Swet parpati of K were found to be stoichiometrically HgS and KNO3

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Abstract  

Sediments from the Admiralty Bay, King George Island, Antarctica, were investigated by 57Fe Mössbauer spectroscopy, X-ray diffractometry, and radiometry. Quartz, feldspar, chlorite, calcite, dolomite, mica, kaolinite, hematite and magnetite were identified as constituent minerals in the sediment samples. The phase composition and the iron distribution among the crystallographic sites of iron-bearing minerals (silicates, magnetite and hematite) of samples from different location have been derived from the complex Mössbauer spectra. At different locations sediments had significant characteristic differences in the mineral composition, in the iron distribution among the crystallographic site of silicates, and in the specific radioactivity of Cs radionuclides. These results indicate differences in the rock formation and alteration by the sediments in this maritime part of Antarctica. There is a much higher amount of iron oxides in the sediments from south part of the geological fault across the Admiralty Bay than in the north part. This can be associated with much more alteration in the rocks in the south part compared to the northern one. This finding can contribute to the question of the history of the formation and alteration of volcanic rocks in the border of Antarctica.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: E. Kuzmann, Z. Klencsár, Z. Homonnay, A Vértes, G. Braga, A. De Oliveira, V. Garg, M. Bódogh, I. Kotsis and A. Nath

Abstract  

57Fe and 151Eu Mössbauer spectroscopy as well as RF susceptibility measurements were applied to study the effects of Pr substitution either into the rare earth or into the Ba site in Eu1–xPrxBa2Cu3O7– and EuBa2–xPrxCu3O7–, respectively. Site mixing of Pr between the rare earth and Ba sites could be excluded by the utilization of 57Fe Mössbauer spectroscopy. It was found that there exists a correlation between the 151Eu isomer shift and the onset temperature of the superconducting transition independent of the location of Pr. RF susceptibility measurements provide an evidence for a difference in the magnetic moment of Pr substituted for the Eu or Ba sites. The obtained results can be explained by hole filling as the dominant effect of Pr substitution.

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