Combustion synthesis and EIS characterization of TiO_2-SnO_2 system

摘要

TiO_2 is an insulator, but using specific dopants, can modify sharply its electronic structure towards semiconducting behavior. This type of response is widely applied in many electrochemical and electrocatalytical devices, namely chlorine production, hydrocarbon oxidation, CO and CO_2 hydrogenation and as electroactive substrata for biological cell growth. Combustion synthesis is a very simple, rapid and clean method for material preparation, which will be used in the preparation of the (1 - x)TiO_2-xSnO_2, x = 0.05-0.3. Tin oxalate and titanium isopropoxide are used as precursors for the synthesis. The as-prepared powders are fine and homogeneous, the average particle size is in the range of 5-10nm, powders and ceramic compact bodies are characterized by DRX, SEM-TEM-EDX, DTA-TG and EIS. The impedance spectroscopy of the sample 10 mol percent of SnO_2 indicates the presence of several phases which promote a matrix composite based in an electrical TiO_2 insulator compatible with an electronic conducting phase tin rich. This could be attributed to the spinodal decomposition effect observed in TiO_2-SnO_2 system.