Comparison of Polythionates as Precursors for the Formation of Thallium Sulfide Layers

Abstract

The processes of obtaining layers of thallium, sulfides, Tl_xS_y, by the sorption-diffusion method on polyamide 6 using solutions of lower polythionates - sodium trithionate and tetrathionate, Na₂S₃O₆, Na₂S₄O₆, potassium pentathionate, K₂S₅O₆, and of dodecathionic acid, H₂S₁₂O₆, as precursors of sulfur are compared. The concentration of sorbed sulfur increases with increasing the duration of treatment, the concentration and temperature of precursor solution. It rather significantly also depends on the nature - sulfurity of polythionate, i. e. on the number of sulfur atoms in the polythionate anion: effectiveness of sulfurization using solutions of dodecathionic acid is significantly higher than that of lower polythionates. Thallium sulfide layers are formed on the surface of polyamide after the treatment of sulfurized polymer with Tl(I) salt solution. The concentration of thallium in the layer increases with the increase of initial sulfurization duration and in case of H₂S₁₂O₆ solution used - on the temperature of this process. The results of X-ray diffraction analysis confirmed the formation of thallium sulfide layers in the surface of polyamide 6. The phase composition of layer changes depending on the conditions of initial treatment in a H₂S₁₂O₆ solution. Five thallium sulfide phases, two forms of TlS, Tl₂S₂, Tl₄S₃ and Tl₂S₅ were identified in the composition of the layers treated for different time with a solution of dodecathionic acid at the temperature of 20 °C and 30 °C and then with Tl(I) salt solution by X-ray diffraction but the maxima of TlS and Tl₂S₅ phases predominate in the diffractograms.

http://dx.doi.org/10.5755/j01.ms.17.4.774