Synthesis of Copper-Doped Nanocrystalline Tin Stannate by Thermal Decomposition of a Precursor

Abstract

Zinc hydroxostannate ZnSn(OH)6, containing 5 mol.% Cu, was obtained from hydrochloric acid solutions of tin(IV), zinc and copper by adding sodium hydroxide to pH = 8–9. The thermolysis process of the obtained sample and the phase composition of the decomposition products were studied using thermal analysis, X-ray diffraction, and scanning electron microscopy. It was shown that the main stages of dehydration are completed at a temperature of about 350 °C and, as a result of thermolysis, an X-ray amorphous product is formed, from which a solid solution of copper in zinc stannate is obtained at an annealing temperature above 650 °C. At an annealing temperature of 800 °C, a mixture of nanocrystalline tin dioxide SnO2 with a cassiterite structure and copper-doped zinc orthostannate Zn2SnO4 with a spinel structure is formed. The room temperature sensors based on ZnSnO3 and carbon nanofibers as a conductive additive showed high response to NO2 (–6.1% to 2 ppm NO2).