Phase evolution and sintering kinetics of hydroxyapatite synthesized by solution combustion technique

Area of Science:

• Materials Science
• Ceramics Engineering
• Biomaterials

Background:

• Hydroxypatite (HAp) is a crucial biomaterial with applications in bone regeneration and dental implants.
• Controlling the synthesis and sintering behavior of HAp is essential for optimizing its properties.
• Solution combustion synthesis offers a potentially efficient route for HAp powder production.

Purpose of the Study:

• To synthesize phase-pure, stoichiometric hydroxypatite (HAp) powder using the solution combustion technique.
• To investigate the phase evolution and sintering kinetics of the synthesized HAp.
• To determine the dominant densification mechanism and activation energy for sintering.

Main Methods:

• Solution combustion synthesis using calcium nitrate, di-ammonium hydrogen phosphate, and citric acid.
• Calcination at various temperatures to study phase evolution.
• Rietveld analysis for crystal structure, phase purity, and stoichiometry assessment.
• Dilatometry to study sintering behavior, kinetics, and activation energy.

Main Results:

• Phase-pure and stoichiometric hydroxypatite powder was successfully prepared.
• Rietveld analysis confirmed the phase purity and stoichiometry of the synthesized HAp.
• Dilatometry revealed grain boundary diffusion as the dominant densification mechanism during initial sintering.
• The activation energy for sintering was calculated to be 438 kJ/mol, aligning with reported values.

Conclusions:

• Solution combustion is an effective method for producing high-quality, phase-pure, and stoichiometric hydroxypatite powder.
• Understanding sintering kinetics and mechanisms is vital for tailoring HAp properties for specific applications.
• The determined activation energy provides valuable data for optimizing HAp sintering processes.