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Abstract  

Precise calorimetry was performed for (AgI)x(AgPO3)1–x and (AgI)x(Ag2PO3.5)1–x glasses with very high AgI compositions (x0.75). The glasses showed -glass transitions due to the freezing-in of the rearrangement of conductive Ag+ ions. Magnitude of the associated heat-capacity jump increased with increasing the AgI composition in the respective glass systems, and was larger in the former system than in the latter when compared at the same AgI composition. All the results were well explained by the amorphous AgI aggregate model for the AgI-based fast ion conducting glasses, indicating the appropriateness of the model for the structure of the glasses with high AgI compositions. The formation of the hypothetical bulk amorphous AgI was also indicated in the glasses at the highest limit of AgI composition.

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Abstract  

To investigate the nm-size dependence of structural and thermal properties for AgI, the formation of composites between AgI and porous silica with controlled pore diameters of 10, 15, 30, and 50 nm was examined. The introduction of AgI within the micropores of the porous silica was performed successfully by a salt-bridge precipitation method with using AgNO3 and KI aqueous solutions. The AgI formed within the micropores was identified to be β/γ-AgI, independent of the pore size of 10-50 nm, by powder X-ray diffractometry. In differential scanning calorimetry, the composites showed thermal anomaly at around 150C on heating due to the phase transition from β/γ -AgI to α -AgI as in the case of bulk crystalline AgI (T trs=147C). However, the transition temperature from α-AgI to β/γ -AgI on cooling decreased remarkably with the decrease of the pore size from 50 to 10 nm. The result indicates the possibility for AgI particles with diameter less than 10 nm to exist as α -AgI even below 100C.

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Summary The temperature and pressure dependencies of the structure and transport properties of AgI1-xClx are studied by means of molecular dynamics. From the results of the calculations, the P-T phase diagram for the AgI0.8Cl0.2 system has been obtained. The phase diagram indicates that the superionic phase transition temperature increase with the application of pressure. It is also pointed out that AgI1-xClx has a tendency of phase separation.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: N. St. Kalmykov, A. Arhipov, A. Abramov, N. Ivanova, B. Iofa, O. Pronina, Yu. Sapozhnikov, and A. Anisimov

Abstract  

Liquid-liquid extraction of several cations by some oxa-tia- and tia-crown ethers was studied. Sr(II), Pb(II) and Ag(I) were taken as hard, borderline and soft Lewis acids, respectively. Trace amounts of210Sr and110mAg were used as chemical yield monitors. The results were explained by the Pearson theory. Some of the examined compounds posses high affinity towards Ag(I) and Pb(II) extraction. The distribution coefficent for Ag(I) reached the value of 140.

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Abstract  

The complexes of the general formula MLSCN (M=Cu(I), Ag(I), L=2,2′-bipyridine=2-bipy, 4,4′-bipyridine=4-bipy or 2,4′-bipyridine=2,4′bipy) have been prepared and their IR spectra examined. The nature of metal-ligand coordination is discussed. Thermal decomposition in air of these complexes occurred in several successive endothermic and exothermic processes and the residue was Cu2O and Ag, respectively.

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Abstract  

An investigation on the thermodynamics of complex formation between Ag(I) ion and two tripodal ligands tris[(2-pyridyl)methyl]amine (TPA) and 6,6′-bis-[bis-(2-pyridylmethyl)aminomethyl]-2,2′-bipyridine (BTPA) has been carried out in the aprotic solvents dimethylsulfoxide (DMSO) and dimethylformamide (DMF) by means of potentiometry and titration calorimetry. The results for TPA are compared with those already obtained for other aliphatic tripodal polyamines. In general, the TPA ligand forms complexes less stable than 2,2′,2″-triaminotriethylamine (TREN) and tris(2-(methylamino)ethyl)amine (Me3TREN) as a result of the combination of higher structural rigidity of TPA and lower σ-donor ability of pyridinic moieties with respect to primary and secondary amines. The same trend is found if the stability of Ag(I) complex with TPA is compared with that of tris(2-(dimethylamino)ethyl)amine (ME6TREN), despite the pyridinic nitrogen is formally a tertiary one. Theoretical calculations run to explain the reasons of this weaker interaction indicate that this difference is due to solvation, rather than to steric or σ-donor effects. The ligand BTPA is able to form bimetallic species whose relative stability is largely influenced by the different solvation of Ag(I) ion in DMSO and DMF rather than by the difference in the dielectric constants of these two media.

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Abstract  

A rapid and selective method has been developed for the substoichiometric extraction of Ag/I/with 1,2,3-benzotriazole /1,2,3-BT/ in chloroform in the presence of versenate. The effect of various parameters such as pH, time of equilibration, solvent, anions, cations, etc., on the extraction coefficient value has been studied. The stoichiometry of the extracted species of 11 /Ag:1,2, 3-BT/ was obtained by the slope ratio method and substoichiometric extraction. Decontamination factors for most elements in the substoichiometric extraction of Ag/I/ were found to be higher than 104.

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Abstract  

Iodide retention by AgCl, a potential sorbent in high-level waste (HLW) storage systems, was determined. The kinetics and steady state sorption of iodide were determined in single and mixed electrolytes of NaNO3, and NaCl at ionic strengths of 25 and 50 mM. Iodide retention involved the conversion of AgCl to AgI. This conversion increased rapidly within 0.02 hours, and retention maxima of 0.92 and 1.0 mol·l·mol−1 Ag occurred for low and high ionic strengths, respectively. These short-term studies indicated that AgCl would be an effective scavenger of I in HLW containment systems.

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Abstract  

The extraction properties of Ag(I), Cd(II), In(III), Sn(II), Sn(IV), Sb(III), and U(VI) from aqueous KI/H2SO4 solution into a mixture of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK) and cyclohexanone (CHO) were studied. Both single-step batch and SISAK2 methods were used. The oxidation of Sn(II) to Sn(IV) by iodine and complexation of Sn(IV) by 2,3-dimercapto-propanol-1 (BAL) were also investigated. A method for rapid and continuous separation of indium from tin was developed for investigation of short-lived indium fission products.

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Abstract  

The nature of the β to α phase transition in silver iodide was investigated by conventional and modulated temperature DSC and dielectric property measurements. On cooling, the high temperature phase remained stable 2.5C below its normal transition temperature even at a very slow cooling rate 0.2C h–1. Dielectric property measurements under conventional and microwave heating suggested an anomalous effect of the latter on the β to α phase transition in this material.

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