Study of alkali borate glass containing tin by the Mössbauer effect

A number of alkali borate glasses containing tin oxide of base composition (100?X) % B₂O₃ + X % Me₂O + Y SnO₂ where Me = Li, Na or K, X = 10, 20 or 30 and Y is the quantity of SnO₂ introduced, were prepared and studied by the Mössbauer effect. It was shown that the value of the isomer shift increases while the value of the quadrupole splitting decreases with increasing ionic radius of the alkali ion. The value of the isomer shift and quadrupole splitting decrease with increasing alkali content. The observed asymmetry in the absorption lines was attributed to the Goldanskii effect. An explanation is suggested for the dependence of the ratio of the various valence and coordination structural states of the tin in the glass on the amount and nature of the alkali ions.     

Synthesis of tin oxide nanosized crystals embedded in silica matrix through sol–gel process using alkoxide precursors

Materials made of tin oxide nanocrystals homogeneously dispersed into a silica glass matrix have been elaborated through sol–gel processing. Addition of strong acids was used to control the hydrolysis–condensation in tin and silicon alkoxides mixed alcoholic solutions. Fourier transform infrared spectroscopy (FTIR) and Small angle X-ray scattering (SAXS) measurements show that the introduction of HCl allows to synthesize gels containing up to 50% of tin oxide precursor without significant modification of the pure silica gel network. Thermal treatments of slowly dried bulk gels induce the crystallization of tin oxide nanoparticles. After firing at 1000 °C, dense materials containing tin oxide nanocrystals (with a mean diameter close to 1–2 nm) are obtained. The crystal size distribution was estimated by X-ray diffraction line profile analysis. The narrowness of this distribution makes these materials interesting for optical applications.     

Di-μ-sulphido-bis[4-methyl-piperidinedithiocarbamate tin(IV)]: Synthesis,characterization, and crystal and molecular structure

The title compound, C₁₅H₂₆SnN₂S₅Cl₂, was prepared, and characterized by means of X-ray and IR measurements. The crystals are monoclinic, space groupP2₁/n, (non standard setting ofP2₁/c, No. 14) witha=12.330(2),b=11.930(1),c=17.055(2) Å,=106.21(1)° andZ=4.The structure was solved by the heavy-atom method, and least-squares refinement of the structural parameters led to a conventionalR factor of 0.028 for 1284 independent reflections. The structure consists of discrete dimeric units with the metal coordinated to six sulphur atoms. The IR spectrum is consistent with the presence of the sulphur bridge atoms between the two metal ions.     

Square-wave voltammetry and impedance spectroscopy in tin doped melts with the compositions xNa2O · 15Al2O3 · (85 − x)SiO2 (x = 8.5, 11 and 16)

Glasses with the base compositions xNa₂O · 15Al₂O₃ · (85 ? x)SiO₂ (x = 8.5, 11 and 16) doped with 0.5 mol% SnO₂ were investigated by both square-wave voltammetry and impedance spectroscopy in the temperature range from 1300 to 1600 °C. Each recorded square-wave voltammogram exhibits a well pronounced peak attributed to the Sn²⁺/Sn⁴⁺-redox pair. Impedance spectra were measured in a frequency range from 0.1 to 10⁵ s^?1 as a function of the superimposed dc-potential and were simulated using an equivalent circuit taking into account the resistivity of the melt, the electrochemical double layer, a resistor attributed to a kinetically hindered electron transfer and a Warburg parameter which accounts for the diffusion process of Sn⁴⁺ and Sn²⁺ to and from the electrode. Additionally, two impedance elements, a resistor and a capacitance both attributed to adsorption processes were necessary to fit the impedance spectra.