Structural characterization of zinc-substituted hydroxyapatite prepared by hydrothermal method

Area of Science:

• Materials Science
• Biomaterials Engineering
• Inorganic Chemistry

Background:

• Hydroxyapatite (HA) is a key biomaterial, but its properties can be tuned.
• Incorporating zinc (Zn) into HA (Zn-HA) offers potential for enhanced functionalities.
• Understanding the synthesis-structure-property relationships of Zn-HA is crucial for its applications.

Purpose of the Study:

• To synthesize zinc-substituted hydroxyapatite (Zn-HA) powders using a hydrothermal method.
• To investigate the effect of zinc substitution on the structural, morphological, and thermal properties of HA.
• To compare the influence of different preparation solutions (NaOH vs. NH3) on Zn-HA characteristics.

Main Methods:

• Hydrothermal synthesis using calcium nitrate, ammonium phosphate, and zinc nitrate.
• Characterization techniques included X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM).

Main Results:

• Zinc substitution for calcium in HA was confirmed, with higher substitution levels achieved using NaOH solution.
• Zn substitution led to decreased crystallinity and altered lattice parameters due to the smaller ionic radius of Zn2+ compared to Ca2+.
• Zn substitution restrained crystal growth and reduced the thermal stability of Zn-HA, with decomposition occurring at lower temperatures.

Conclusions:

• The preparation solution significantly impacts the zinc substitution content and properties of Zn-HA.
• Zinc substitution influences the crystallinity, microstructure, morphology, and thermal stability of hydroxyapatite.
• Zn-HA exhibits altered thermal decomposition behavior dependent on the zinc content and synthesis conditions.