Thermal expansion coefficient determination of pure, doped, and co-doped anatase nanoparticles heated in sealed quartz capillaries using in-situ high-temperature synchrotron radiation diffraction

Synchrotron radiation diffraction was conducted in-situ and at high temperature to establish the lattice parameters of pure/undoped, doped, and co-doped anatase nanoparticles. The nanoparticles were heated from room temperature to 950 °C in sealed quartz capillaries. The effect of pressure, doping (aluminium or indium), and co-doping (indium-chromium or silver-chromium) on the thermal expansion coefficients of nanocrystalline anatase was established. Synchrotron radiation diffraction at high temperature and in-situ, transmission electron microscopy, and the Rietveld refinement method were used to characterise the anatase nanoparticles. The anisotropy of the thermal expansion, α(a)/α(c), for pressurised anatase nanoparticles was smaller than that for anatase heated in unpressurised air or argon, and it was much smaller in a vacuum.