In situ high-pressure and high-temperature diffraction experiments on pure and Ag-doped TiO2 nanopowders

The phase stability of amorphous and nanostructured TiO2 powders was investigated. The surface free energy and the surface stress dominate the thermodynamic phase stability for ultrafine-grained materials. Both parameters may be tuned with sufficient accuracy by modifying the surface chemistry of the nanoparticles and by applied pressure, respectively. Pure and Ag-doped nanostructured titanium dioxide samples were produced using the sot-gel method. Their high-pressure and high-temperature stability domains were determined by in situ X-ray diffraction experiments using synchrotron radiation. (C) 2002 Elsevier Science B.V. All rights reserved.