Preparation of hydroxyapatite via microemulsion route

Area of Science:

• Materials Science
• Nanotechnology
• Biomaterials

Background:

• Hydroxyapatite (HAp) is a crucial biomaterial.
• Controlling HAp synthesis impacts its properties.
• Amorphous HAp requires controlled thermal treatment for crystallization.

Purpose of the Study:

• To synthesize hydroxyapatite (HAp) using a novel microemulsion and pH-shock wave method.
• To investigate the structural and morphological evolution of HAp upon thermal treatment.
• To determine the crystallization temperature and activation energy of HAp.

Main Methods:

• Microemulsion route combined with pH-shock wave method for HAp synthesis.
• Thermal analysis (heating at 650°C and 900°C).
• Characterization of particle size, porosity, and phase composition.

Main Results:

• As-synthesized HAp consisted of amorphous, aggregated particles with mesoporosity.
• Heating at 650°C led to crystallization of A-type carbonate hydroxyapatite (40–120 nm particles) without internal porosity.
• Heating at 900°C induced sintering, forming larger particles composed of HAp and beta-tricalcium phosphate (beta-TCP).
• HAp crystallization occurred at 635°C with an activation energy of 62.7–72.2 kcal/mol.

Conclusions:

• The microemulsion and pH-shock wave method effectively produces mesoporous amorphous HAp.
• Controlled thermal treatment is critical for transforming amorphous HAp into crystalline phases (HAp and beta-TCP).
• The study provides insights into HAp crystallization kinetics and phase transformations relevant for biomaterial applications.