The author studied on hydrothermal reactions from 1981 to 2019 at the Research Laboratory of Hydrothermal Chemistry, Kochi University, and one of his research topics was hydroxyapatite.During the research process, a few unique techniques were developed such as high temperature mixing method to prepare hydroxyapatite crystals with high crystallinity, anion exchange of apatite single crystals under alkaline hydrothermal conditions, and hydrothermal hot-pressing technique to prepare hydroxyapatite ceramics.This paper reviews research on hydroxyapatite conducted by the author and his research group.
Kazumichi Yanagisawa (Thu,) studied this question.