Acoustic vibrations of amorphous and crystalline ZrO2–TiO2 nanoparticles

• Acoustic vibrational modes of ZrO2–TiO2 nanoparticles was analysed by low-frequency Raman spectroscopy.
• The low-frequency Raman scattering was used for determination of size distribution of amorphous nanoparticles.
• The phase transition from amorphous to nanocrystalline phase was monitored by low frequency Raman scattering.

Acoustic vibrational modes of ZrO2–TiO2 nanoparticles (ZT) have been observed and analyzed by means of low-frequency Raman spectroscopy (LFRS). The low-frequency Raman peak has been observed in the spectra of amorphous as well as of crystalline ZT nanoparticles. The results obtained by the LFRS have been compared to the results obtained by high-resolution transmission electron microscopy (HRTEM). After the method has been tested, the LFRS has been used to investigate the influence of the amount of dopant (Ti4+) and the annealing temperature on size distributions of the ZT nanoparticles. The observed reduction of the particles’ growth-rate with Ti doping was ascribed with increase of defects in nanoparticles. Also, a discontinuity in the particles’ growth-rate at the temperatures between 500 °C and 600 °C was observed. It is at these temperatures that the phase transition from amorphous to nanocrystalline phase occurs.