Microwave-hydrothermal synthesis and characterization of hydroxyapatite nanocrystallites

doi:10.1016/j.matlet.2011.07.095

Materials Letters

Volume 65, Issues 23–24, December 2011, Pages 3388-3390

https://doi.org/10.1016/j.matlet.2011.07.095 Get rights and content

Abstract

Hydroxyapatite (HAP) nanocrystallites were prepared using calcium nitrate tetrahydrate, phosphoric acid and 1,2-ethylenediamine, as raw materials by microwave-hydrothermal (M-H) method in the temperature range of 100-140 °C. Obtained reaction products were characterized by XRD, FTIR and SEM. The results showed the crystallization of single HAP phase at all the synthesis temperatures. HAP nanoparticles with high crystallinity could be synthesized at 140 °C for only 1 min. It was observed that the morphology of as-obtained HAP powders transformed from rod-like to prism-like nature with the increase of the reaction temperature. The present study indicates that the M-H method is a facile one-pot way to obtain phase pure and high crystalline HAP nanoparticles.

Highlights

► Hydroxyapatite nanocrystallites were prepared by microwave-hydrothermal method. ► Obtained reaction products are phase pure and high crystallinity degree. ► Morphologies of the nanoparticles evolved with synthesis conditions.

Introduction

Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HAP) is a widely used biomaterials because of its good biocompatibility, bioactivity and chemical similarity to natural bone and teeth [1], [2], [3], [4], [5]. Varied HAP preparation approaches including mechanochemical route [6], coprecipitation technique [7], [8], sol–gel method [9], [10], hydrothermal reaction [11], [12], [13], microemulsion route [14], etc., have been developed. However, the preparation processes of these methods usually are complex and time-consuming to obtain HAP nanoparticles with controlled morphology and high crystallinity degree.

Microwave-hydrothermal (M-H) reaction has been used as an effective method for the synthesis of nanoparticles of various oxides [15], [16], [17]. Compared with conventional methods, M-H synthesis has many distinct advantages, such as rapid heating to crystallization temperature, accelerating chemical reaction rates, enhancing crystallinity and decreasing byproduct. Furthermore, it is simple, energy efficient and economical. To our knowledge, however, there are only few studies about preparation of HAP by M-H method [18]. In this study, one-pot facile synthesis of phase pure high crystalline HAP nanoparticles by M-H method was investigated; the products were characterized by XRD, FTIR and SEM.

Section snippets

Experimental

The analytical grade reagents of calcium nitrate tetrahydrate, phosphoric acid, and 1,2-ethylenediamine were used as starting materials. The reagents were purchased from Shanghai Chemical Co. Ltd.

All the M-H reactions were carried out in the microwave-accelerated reaction system: MARS-5 (CEM, USA, frequency = 2.45 GHz). This system operates at a maximum power of 1200 W, and power can be varied from 0 to 100% and is controlled by temperature to a maximum of 240 °C. The syntheses were performed in

Results and discussion

The XRD patterns of various M-H syntheses products are represented in Fig. 1(1). All the diffraction peaks can be indexed to the hexagonal phase of HAP (space group of P6₃/m, PDF No. 00-054-0022). No any other crystalline impurities are observed, indicating the high purity of the products. The diffraction peaks become sharp and well resolved with the increase of the reaction temperature and/or time, which shows improvement in the crystallinity nature of the as-obtained products. It indicates

Conclusions

Phase pure nano crystalline HAP has been successfully prepared by M-H method in the temperature range of 100-140 °C. XRD and FTIR results proved that obtained products are calcium-deficient HAP. With increasing hydrothermal temperature and/or time, the crystallinity degree and crystallite size of the HAP nanoparticles increased, and the morphology of the HAP powder transformed from rod-like to prism-like nature. The high crystalline nano HAP powders with average crystallite size of 54.7 nm could

Acknowledgments

This project was supported by the Science Foundation of Shandong Province (2008E24).

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Microwave-hydrothermal synthesis and characterization of hydroxyapatite nanocrystallites

Abstract

Highlights

Introduction

Section snippets

Experimental

Results and discussion

Conclusions

Acknowledgments

Biomaterials

Mater Lett

Biomaterials

Biomaterials

Mater Lett

Ceram Int

J Colloid Interface Sci

J Solid State Chem

Biomaterials

Solid State Ionics