Anatase-Rutile Phase Transformation of Cu2+ Doped TiO2 in a Non-Reducing Atmosphere

Abstract

The anatase-rutile phase transformation of Ti02 containing various amounts of ci+ ions was investigated in argon atmosphere by means of xray diffraction and electron spin resonance spectroscopy. The samples were prepared by the sol-gel method from titanium(lV) isopropoxide and copper(II) nitrate. The amorphous samples were calcined in argon atmosphere for 2 h at different temperatures. In the presence of Cu 2 +, the anatase-rutile transition temperature is lower than the corresponding one in pure Ti02. The transformation in argon atmosphere changes the transition temperatures due to the spontaneous reduction of Cu 2 + and Ti 4 + ions to metallic copper and Ti 3 + respectively. The broadening of the electron spin resonance spectra from this ion show that Ti 3 + ions are present in different sites into the Ti02 lattice. This are confirmed by electron spin resonance and allowed liS to follow the phase transformation in detail.