# Incorporation and deposition behaviors of Zn into the channel of hydroxyapatite

## TL;DR

Zinc was successfully incorporated into hydroxyapatite channels and released as ZnO particles, offering a new method for creating metal oxide-decorated materials useful in catalysis.

## Contribution

A novel method for achieving the highest Zn content in hydroxyapatite channels and subsequent ZnO deposition is demonstrated.

## Key findings

- Zn incorporation into hydroxyapatite channels was confirmed using X-ray diffraction and spectroscopy techniques.
- Zn was released as ZnO fine particles, uniformly distributed on hydroxyapatite particles.
- The method shows potential for creating metal oxide-decorated hydroxyapatite for catalytic applications.

## Abstract

Zn was successfully incorporated into the channel of hydroxyapatite by loading of Zn and subsequent heat treatment, leading to a Hap with the largest Zn content in the channel compared with those obtained by the conventional wet chemical process. The incorporation of Zn into the channel was supported by X-ray diffraction analysis combined with Rietveld refinement, infrared spectroscopy, Raman spectroscopy and X-ray absorption spectroscopy analysis. Moreover, we demonstrated that the incorporated Zn was deposited from the channel in the form of ZnO fine particles. Homogeneous distribution of ZnO on hydroxyapatite particles was confirmed by elemental mapping using transmission electron microscopy, suggesting the potential of this methodology to serve as a way of addressing metal oxide-decorated hydroxyapatite, which is attracting attention in the field of catalysis.

Incorporation/release of Zn into/from the hydroxyapatite (Hap) channel upon heat treatment under varying humidity were investigated to find the Hap with the largest Zn content in the channel so far as well as deposition of ZnO fine particle.