Synthesis of mixed cobalt(II)-tin(IV) hydroxide and study of its dehydration products

Abstract

The CoSn(OH)6 sample was prepared by crystallization from the water solutions of tin(IV) and cobalt(II) salts on addition of NaOH and characterized by method X-ray diffraction and electron microscopy. The freshly prepared sample comprised single crystals of cubic shape with an average size of ∼ 200 nm. Dehydration process of CoSn(OH)6 were studied by the thermal analysis. The process of the dehydration of CoSn(OH)6 completed at 300 °C. From the total weight loss the formula of the dehydration product was assumed to be CoSnO3. Conductivity of the initial CoSn(OH)6 was nearly 1·10-4 S/cm and decreased in the course of heating in parallel to the release of the water molecules from the sample. The most probable charge carriers are proton particles located in the adsorption layer on the surface of cubic CoSn(OH)6 particles. During the dehydration conductivity decreased to a level of 10-8 S/cm, corresponding to the conductivity of the amorphous CoSnO3 phase. After storage of the dehydrate sample in air at room temperature an additional conductivity contribution appeared in the sample measured at high frequencies. Possible reason of this effect is the adsorption of water molecules at the high surface of the amorphous CoSnO3 phase.