Effect of Synthesis Temperature on Morphology and Structural Characteristics of Hydroxyapatite Whiskers

Abstract

Synthesis temperature shows important effects on the hydrolysis rate of acetamide (AA) additive and the driving forces for the formation of nuclei and the growth of hydroxyapatite (HA) crystals from aqueous solution. Variation in the temperature in the present work affected neither the constitution & crystallinity of the products nor the crystal growth habit along the c-axis. However, the morphology of products greatly depended on the synthesis temperature and was correlated with the starting pH of the solution. Higher initial pH only provided a basic reference for quickly obtaining supersaturation for the formation of HA nuclei. Lath-or branch-like HA often appeared in the whiskers at high initial pH, being independent of the synthesis temperatures. Neither high nor low temperatures were beneficial to the preparation of long HA with high aspect ratio. 180-200°C seemed to be an appropriate synthesis temperature to prepare long HA whiskers from a solution with Ca/P 1.67 and starting pH 3. The Ca/P ratio of products increased with the temperature, and the whiskers obtained at low temperature had high calcium deficiency.

Hydroxyapatite composite scaffold for bone regeneration via rapid prototyping technique: a review

“…The results indicated that the composite scaffolds have excellent apatite mineralization. Furthermore, the Ca/P ratio (the molar ratio of calcium [Ca] and phosphorous [P] in HAp) increased from 1.23 (HAp 0 Wt.%) to 1.72 (HAp 30 Wt.%), which was close to and even exceeding the standard value of 1.67 (Zhang, 2018). All the Ca/P ratio was measured by energy dispersive x-ray spectroscopy spectra analysis and its standard value was calculated according to its molecular formula Ca 5 (PO 4 ) 3 OH.…”