[en] Highlights: • Basic zinc carbonate as electron cocatalyst was loaded on the surface of Ag-AgCl. • The highest activity of b-Zn/Ag-AgCl was 2.7 times as high as that of Ag-AgCl. • Basic zinc carbonate works as a general cocatalyst to modify Ag-based compounds. • Basic zinc carbonate transfers electrons and inhibits the formation of metallic Ag. Cocatalyst modification is a promising approach for the improved degradation performance of photocatalytic materials owing to rapid charge transfer and interfacial catalytic process. In this work, basic zinc carbonate as a novel cocatalyst was successfully loaded on the surface of Ag-AgCl by a simple impregnation method (the resultant basic zinc carbonate-modified Ag-AgCl was referred as b-Zn/Ag-AgCl). Photocatalytic degradation results suggested that all the b-Zn/Ag-AgCl samples exhibited the enhanced photocatalytic activity, and the highest rate constant of b-Zn/Ag-AgCl was 2.7 times as high as that of the unmodified Ag-AgCl. Importantly, the basic zinc carbonate could work as a general cocatalyst to enhance the photocatalytic activity of other Ag-based photocatalysts (Ag-AgBr, Ag-AgI, Ag-Ag₃PO₄, and Ag-Ag₂CO₃) besides Ag-AgCl. Therefore, it is suggested that basic zinc carbonate functions as an efficient electron cocatalyst to quickly transfer electrons and inhibit the formation of metallic Ag for the promoted photocatalytic performance and stability of Ag-based compounds. This present compound is one of the available and promising cocatalysts for Ag-based photocatalysts.

[en] Short communication

[en] The electrical conductivity, σ, and thermopower, S, of molten (AgX)_1-c(Ag₂Se)_c mixtures (X = Br, I) have been measured as a function of temperature. The conductivity of the mixture is observed to decrease rapidly on the addition of AgX to Ag₂Se and reaches a minimum on the AgX side. The thermopower on the Ag₂Se side decreases gradually as the concentration of AgX increases until c = ∼0.4 at which point there is rapid change to large positive thermopowers. The value of S (+325 μV K^-1 (AgBr), +420 μV K^-1 (AgI)) on the AgX rich side decreases rapidly on addition of Ag₂Se with the result that a minimum value of S (∼-125 μV K^-1) is observed at the composition c = ∼0.4 in both mixtures. A discussion of these results is presented in terms of the change from predominantly electronic transport in liquid Ag₂Se to the predominantly ionic transport in AgX. The increasing importance of the contribution of the inhomogeneous thermopower to the total thermopower of the salt rich compositions is also discussed. The decrease in the electronic conductivity with composition for c≥0.6 is analysed in terms of the Kubo-Greenwood equations. (author)

[en] The 24 s and 2.4 mn short halft-life Ag₁₁₀ and Ag₁₀₈ isotopes were used to determine the quantity of silver remaining in developed nuclear emulsions after exposure to various neutron and gamma radiations. The test carried out should lead to the development and construction of automatic measurement equipment

[en] AgPO₃-AgX glasses present a prepeak in the 0.5-0.9 A^-1 Q-range. Using isotopic substitution in 0.75 AgPO₃-0.25 AgCl(³⁵Cl, ³⁷Cl, natural Cl and ³⁵Cl-³⁷Cl) provokes a dramatic variation in the prepeak intensity, which is strong with ³⁷Cl and disappears for ³⁵Cl. The intensity of the prepeak is well correlated to the contrast term (ρ_AgPO3-ρ_Agx)² corresponding to the square of the relative neutron scattering length densities. As in colloidal systems, this peak can be associated with an intermediate structure of particles lying inside a continuous host. The interparticle distance (comprised between 8 and 10 A) may be analysed in two models; (i) 'AgX' microdomains repeated in the AgPO₃ matrix, or (ii) '(PO₃)∞' chain microdomains repeating inside a connective tissue made essentially of disordered AgI. The latter model could be more appropriate to describe other physical properties such as ionic conductivity. (author). 18 refs.; 5 figs.; 3 tabs

[en] The lower range in Q (from 0.2 to 2 A^-1) of interference functions S(Q) is very sensitive to the nature of the X nucleus and to the concentration of AgX doping salt. In particular, the progressive enrichment in ³⁷Cl isotope in ³⁵Cl-³⁷Cl mixtures gives rise to an increase of a prepeak located at Q ∝ 0.88 A^-1 for the content 0.75 AgPO₃-0.25 AgCl. A very detailed experiment (at the LLB) has been done with five AgI concentrations. This prepeak has been assigned to (111) reflexion in a cfc network in which the diffusing objects are small aggregates of AgI defined by a radius R. The linear variation of the interplanar d distance (2π/Q) versus the volumic fraction in AgI implies necessarily that the diffracting objects are bigger and bigger when AgI content increases. Therefore, one may consider a medium ordering structure of nanoaggregates of AgI embedded inside the phosphate matrix. (orig.)

[en] Tracer ^110mAg was used to investigate the speciation of silver in natural waters, which may contain chloride, sulfide or humate ions. Silver chloride or oxide is readily absorbed from waters by many materials, and some may be photochemically reduced to metallic silver. Absorbed silver, silver chloride and silver sulfide may be distinguished by their desorption behaviour. Humates form complexes with silver chloride, silver sulfide and with the silver cation, which can be separated from smaller species by gel permeation chromatography. (author)

[en] The collargol was synthesized. The technology of collargol obtaining was elaborated. As initial material were used casein and silver nitrate. For each operation of collargol obtaining the optimal conditions were determined.

[en] A radiochemical displacement method for the determination of small amounts of mercury has been developed. The method involves the displacement of spiked (^110mAg) silver from its dithizonate complex in chloroform. The effects of various ions on the extent of displacement are reported. By this process, ∼80 μg of Hg(II) can be determined. The results of this method are highly reproducible

[en] The diffusion coefficient of silver in RbAg₄I₅ was measured in both superionic phases using radiotracer Ag-110m and serial sectioning with a low temperature sectioning apparatus. The activation energies for diffusion in alpha-RbAg₄I₅ and beta-RbAg₄I₅, respectively, are 0.11 +- 0.01 eV and 0.20 +- 0.04 eV. An isotope effect for diffusion was also measured in both superionic phases. Ag-105 and Ag-110m radioisotopes were used with gamma spectroscopy and energy discrimination. The effect is small, with no significant temperature variation, with the value at 333⁰K being 0.12 +- 0.01. The second-order phase transition at 208⁰K has a small effect, if any, on the magnitude of the effect. The data suggest that a highly cooperative transport mechanism is responsible for the unusually high values of both the conductivity and diffusion coefficient. Although it is not possible to deduce the particular mechanism involved, theories inolving ionic polarons, or cooperative motion, such as crowdions or solitons, seem consistent with the observed results