Nanotechnology
I. Benammar; R. Salhi; J. -L. Deschanvres; R. Maalej
Abstract
This work describes the systematic preparation of doped and undoped TiO2 with Er and/or Yb nanoparticles by hydrothermal-assisted sol-gel method with supercritical drying of ethanol, followed by systematic calcination steps at 500°C, 800°C and 1000°C for 2 h. Structural investigation of these ...
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This work describes the systematic preparation of doped and undoped TiO2 with Er and/or Yb nanoparticles by hydrothermal-assisted sol-gel method with supercritical drying of ethanol, followed by systematic calcination steps at 500°C, 800°C and 1000°C for 2 h. Structural investigation of these powders by XRD shows that our samples are crystalline with a tetragonal structure and an anatase phase well crystallized at 500°C. Annealing at 800°C shows a transformation of the anatase phase into the rutile phase, which is well crystallized at 1000°C. XRD analysis shows that the dopants are incorporated into the TiO2 network without phase separation in these nanoparticles. The study of the grain sizes has shown that they have a nanometric size of about 8-12 nm and that their size decreases with Er and/or Yb doping. The elemental analyzes with micro-EDX using SEM confirmed the presence of chemical elements in the TiO2 nanoparticles with the expected atomic ratios. Examination of the SEM images confirmed the XRD observations. They also prove that the nanoparticles are spherical. Optical analysis with excitation at 488 nm shows the presence of three emission bands in the green and red regions. The heat treatment improves the optical, structural and spectroscopic properties and removes impurities due to the preparation conditions.
