Spherical vibrational modes of ZrO2–CuO nanoparticles

The nano-structural changes in zirconia (ZrO2) ceramics upon incorporation of different amounts of the Cu2+ cations and after thermal treatment of the amorphous precursors were investigated by low frequency Raman spectroscopy (LFRS). The spherical vibrational modes were observed for both – amorphous and nanocrystalline ZrO2–CuO (ZC) particles. The procedure how to determine the particle size distribution from the LFRS modes was described and tested on few ZC samples by comparison with transmission electron microscopy results. The method was used to monitor the particle size growth in dependence on dopant concentration and annealing temperatures. The reduction of the particle size growth with doping, as well as the discontinuity in the particle size growth between 500 °C and 600 °C was observed. The first effect was interpreted with an increase of defects in nanoparticles with doping, and the second one by the phase transition from tetragonal to monoclinic phase of ZC particles.