Crystal Morphology of Hydroxyapatite Modulated by Glutamic Acid at Different Hydrothermal Temperatures

Large-sized hydroxyapatite (HA) crystals with different morphologies, such as whisker-like, tubular and plate-form shape were prepared at different hydrothermal temperatures. Reaction solutions with small concentration of Ca2+, PO43- and OH- ions were used for HA synthesis. Phase identifications and morphological characterizations indicated that HA crystal grew along c axis under the modulation of glutamic acid adsorbent. The formation mechanism was explained according to the interfacial structures between glutamic acid and HA, as well as thermodynamic and kinetic considerations of crystal nucleation and growth. Understanding the evolution of crystal morphology in a specified reaction solution might favor to control the shape of crystals by the hydrothermal method.