The growth process of regular radiated nanorod bundles hydroxyapatite formed by thermal aqueous solution approach

Nanorod bundles of hydroxyapatite (nrHA) with ordered radiated structure was successfully prepared through hydrothermal treatment, with the hexadecyltrimethylammonium bromide (CTAB) and sodium citrate as surfactant and crystal modifier, respectively. The results showed that the citrate and CTAB played an important role in assembly of nanorods. Moreover, the pH value of the original solution also can influence the final morphology of products. The possible formation mechanism of nanorod bundle structure was discussed in detail. •Nanobundles of hydroxyapatite with ordered radiated structure was prepared.•CTAB regulates the nucleation and growth of crystal.•Calcium citrate modifies the formation of crystals.•Citrate promote the transformation of CTAB micelles.•Citrate causes a heteroepitaxial growth of crystals. [Display omitted]