Comparison of morphology and phase composition of hydroxyapatite nanoparticles sonochemically synthesized with dual- or single-frequency ultrasonic reactor

摘要

To investigate how a dual- or single-frequency ultrasonic reactor changes the morphology and phase composition of hydroxyapatite nanoparticles (nHAPs), we designed and constructed the preparation of nHAPs using dual- or single-frequency ultrasonic devices, i.e., the single frequency ultrasonic generator with ultrasonic horn (25 kHz), the ultrasonic bath (40 kHz) and the dual-frequency sonochemical systems combined with the ultrasonic horn and the ultrasonic bath simultaneously (25 + 40 kHz). The results showed that the sonicated samples displayed a more uniform shape with less agglomeration than non-sonicated sample. The rod-shaped particles with 1.66 stoichiometry and without a second phase were synthesized successfully in the ultrasonic bath or horn systems. The nHAPs obtained from the dual-frequency ultrasonic systems exhibited a regular rod-shaped structure with better dispersion and more uniform shapes than those of obtained in either ultrasonic bath or horn systems. Additionally, the size of rod-shaped particles obtained in the dual-frequency ultrasound with a mean width of 35 nm and a mean length of 64 nm was smaller than other samples. A possible mechanism is that the dual-frequency ultrasound significantly enhances the cavitation yield over single frequency ultrasound and thus improves the dispersion of particles and reduces the size of the crystals. In addition, irregular holes can be observed in the nanoparticles obtained in the dual-frequency ultrasound. Therefore, the dual-frequency ultrasonic systems are expected to become a convenient, efficient and environmentally friendly synthetic technology to obtain well-defined nHAPs for specific biomedical applications.