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- Author or Editor: A. Garg x
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Abstract
Gamma-ray induced decomposition of solid binary mixtures of KNO3 with halides viz. KCl, KBr and KI has been studied at room temperature. G(NO 2 – ) values were found to vary with absorbed dose. Size and electronegativity of anions and molar composition of halides are the other factors influencing radiolysis.
Abstract
A thermal neutron activation method has been developed for the determination of Cu in Cu–Pb–Zn ores and chalcopyrite ore concentrates using the reaction63Cu(N, 
)64Cu. The samples were irradiated with thermal neutrons from an241Am–Be neutron source and the annihilation -radiations of 0.511 MeV were counted on 3
×3 NaI(T1) detector coupled with single channel pulse height analyzer. The method is nondestructive, economical and ideal for bulk analysis of ores with 1–16% Cu.
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.
Abstract
NO
3
–
may also contribute. The overall rate constants are 0.13×10–6 (LiNO3), 1.05×10–6 (NaNO3), 10.10×10–6 (KNO3), 9.50×10–6 (RbNO3) and 25.50×10–6 (CsNO3) kGy–1.Abstract
The 
-ray induced decomposition of several inorganic nitrates CsNO3, TlNO3, Mg/NO3/2.6H2O, Ca/NO3/2.4H2O, Hg/NO3/2, Hg/NO3/2.2H2O, Pb/NO3/2 and Al/NO3/3.9H2O has been studied at an absorbed dose of {5 Mrads. G/NO
2
–
/ is affected by the outer cation and depends mainly on its valency and ionic size. G/NO
2
–
/ for hydrated mercuric nitrate is always higher as compared to that for the anhydrous mercuric nitrate at various doses. Water of crystallization might provide extra factors to facilitate the decomposition of the hydrated nitrate compared to that for the anhydrous salts. In most cases G/NO
2
–
/ decreases exponentially with dose but in cases of CsNO3, Mg/NO3/2.6H2O and Al/NO3/3.9H2O it varies linearly.
Abstract
Gamma-ray induced decomposition of some divalent nitrates, viz. Mg(NO3)2·6H2O, Ca(NO3)2·4H2O, Sr(NO3)2, Ba(NO3)2, Zn(NO3)2·6H2O, Cd(NO3)2·4H2O, Hg(NO3)2·2H2O, Mn(NO3)2·4H2O, Cu(NO3)2·3H2O and trivalent nitrates, viz. Al(NO3)3·9H2O, Fe(NO3)3·9H2O, Cr(NO3)3·9H2O, Y(NO3)3·6H2O, In(NO3)3·3H2O, La(NO3)3·6H2O, Ce(NO3)3·6H2O, Pr(NO3)3·6H2O, Bi(NO3)3·5H2O has been studied in solid state at room temperature. G(NO 2 – ) values (after applying appropriate dose correction) have been found to vary in the range 0.12–3.16 and 0.069–2.15 for divalent and trivalent nitrates respectively. G'-values were calculated by dividing G by the ratio of number of electrons in nitrate ion to the total number of electrons in the nitrate salt. Cation size, its polarizing power, available free space in the crystal lattice and the number and location of water molecules seem to play a dominant role in radiolytic decomposition. For Zn, Sr, In, La and Ce nitrates dose variation studies have been carried out.
Abstract
Half life of56Mn in Mn, MnCl2.4H2O, KMnO4, MnO2, MnSO4.4H2O and that of128I in I2, NaI, KI, KIO4, HIO4, KIO3 was measured. The nuclides were produced by thermal neutron bomabardment in241Am-Be neutron source and their gamma activities were measured using a NaI/T1/ detector. Half life of56Mn varied with the change in oxidation state. No such systematic variation was observed for the half life of128I but it is affected by the nature of cation or anion attached to it. The change in decay constant, 
/ was also calculated.
Abstract
A RNAA method has been developed for the simultaneous determination of Rb and Cs in geological samples. The method is based on precipitation with sodium tetraphenylborate followed by NaI(Tl) gamma spectrometry. Three mica dust particulate samples and two USGS standard rocks, BCR-1 and W-1 were analyzed. Dipicrylamine (DPA) and 2-thenoyl-trifluoroacetone (TTA) in nitrobenzene were also used for solvent extraction. The precipitation method is better than solvent extraction.
Abstract
Mössbauer isomer shift /
/ and quadrupole splitting /
EQ/ values in a series of isostructural compounds correlate well to give linear relationship provided the sign of electric field gradient /EFG/ is assigned to the EQ. The correlation has been used in predicting the sign of EFG for some monosubstituted pentacyanoferrate/II/ complexes. Usefulness of such correlations and its limitations are presented.
