Synthesis of high purity submicrometeric spherical particles are of considerable interest for a wide variety of applications, ranging from electronics via ceramics, catalysts to bioceramic due to their unique properties that are primary determined by size, composition and structure. In this paper, the synthesis of carbonate calcium hydroxyapatite by a spray pyrolysis process in an ultrasonic periodical physical field is analyzed. The formation mechanism of aerosol droplets is discussed and the particle size is derived on the assumption that the aerosol droplet represents a mechanical oscillator exited by complex waves which propagate inside the reactor. The particle size distribution is analyzed considering the degeneration of the forced frequency of the ultrasonic oscillator in those complex waves. The phase composition, structure and substructure so obtained of calcium hydroxyapatite particles are investigated by using X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM) analysis. A fully agreement between the theoretical predicted discrete values for structure and substructure elements (particles and subparticles) and their population balances and experimental values obtained by SEM measurements was found. From that reason, it was evidently confirmed that the process of aerosol/powder particle synthesis can be regarded as a deterministic process.

Keywords: calcium hydroxyapatite, ultrasonic spray pyrolysis, structure, substructure, modelling/designing