Abstract

Chromium titanium oxide (CTO) Cr_2 − xTi_xO₃ (x = 0.05 to 0.4) is the first gas-sensitive resistor material successfully to be commercialised since tin dioxide in the 1960s. Microspheres were synthesised by the sol–emulsion–gel method and characterised by X-ray diffraction, scanning electron microscopy (SEM/EDAX) and X-ray photoelectron spectroscopy (XPS). Three differently sized microspheres of size 10, 2 and 0.7 µm were synthesised. The microspheres showed minimal variation in size and good compositional homogeneity. The CTO powders fired at 1000 °C crystallised as single phases for Cr_1.95Ti_0.05O₃, Cr_1.9Ti_0.1O₃ and Cr_1.8Ti_0.2O₃. For x > 0.2 the formation of a secondary CrTiO₃ phase was noted. EDAX and XPS measurements revealed the absence of impurities and a surface segregation of the Ti atoms.