The size control of materials is of great importance in research and technology because materials of different size and shape have different properties and applications.

This paper focuses on the synthesis of hydroxyapatite in ultrasound fields of different frequencies and intensities with the aim to find the conditions which allow control of the particles size. The results are evaluated by X-ray diffraction, Transmission Electron Microscopy, morphological and sedimentation analyses. It is shown that the hydroxyapatite particles synthesized at low intensity non-cavitation regime of ultrasound have smaller size than those prepared at high intensity cavitation regime. The explanation of observed results is based on the idea of formation of vortices at the interface between phosphoric acid and calcium hydroxide solution where the nucleation of hydroxyapatite particles is taken place. Smaller vortices formed at high frequency non-cavitation ultrasound regime provide smaller nucleation sites and smaller resulting particles, compared to vortices and particles obtained without ultrasound. Discovered method has a potential of industrial application of ultrasound for the controlled synthesis of nanoparticles.

材料的尺寸控制在研究和技术中非常重要，因为不同尺寸和形状的材料具有不同的特性和应用。

本文着眼于在不同频率和强度的超声场中合成羟基磷灰石，目的是寻找可以控制粒径的条件。通过X射线衍射，透射电子显微镜，形态学和沉降分析来评估结果。结果表明，在超声低强度非空化条件下合成的羟基磷灰石颗粒的尺寸小于在高强度空化条件下制备的羟基磷灰石颗粒的尺寸。对观察到的结果的解释是基于在磷酸和氢氧化钙溶液之间发生羟基磷灰石颗粒成核的界面处形成涡旋的想法。与没有超声的涡流和颗粒相比，在高频非空化超声条件下形成的较小的涡流提供较小的成核位点和较小的最终颗粒。发现的方法具有用于超声控制纳米粒子合成的工业应用潜力。