Synthesis, Structure, and Luminescent Properties of Europium-Doped Hydroxyapatite Nanocrystalline Powders

Carmen Steluta Ciobanu,Florian Massuyeau,Liliana Violeta Constantin,Daniela Predoi,Simona Liliana Iconaru,Adrian Costescu

doi:10.1155/2012/942801

Abstract

The luminescent europium-doped hydroxyapatite (Eu:HAp, Ca10−xEux(PO4)6(OH)2) with0≤x≤0.2nanocrystalline powders was synthesized by coprecipitation. The structural, morphological, and textural properties were well characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The vibrational studies were performed by Fourier transform infrared, Raman, and photoluminescence spectroscopies. The X-ray diffraction analysis revealed that hydroxyapatite is the unique crystalline constituent of all the samples, indicating that Eu has been successfully inserted into the HAp lattice. Eu doping inhibits HAp crystallization, leading to a decrease of the average crystallite size from around 20 nm in the undoped sample to around 7 nm in the sample with the highest Eu concentration. Furthermore, the samples show the characteristic5D0→7F0transition observed at 578 nm related to Eu3+ions distributed on Ca2+sites of the apatitic structure.

Highlights

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) belongs to the apatite family with general formula Ca10(PO4)6X2, X being a fluorine, chlorine ion, or a hydroxyl group
The luminescent europium-doped hydroxyapatite (Eu:HAp, Ca10−xEux(PO4)6(OH)2) with 0 ≤ x ≤ 0.2 nanocrystalline powders was synthesized by coprecipitation
The structural, morphological, and textural properties were well characterized by Xray diffraction, scanning electron microscopy, and transmission electron microscopy

Summary

Introduction

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) belongs to the apatite family with general formula Ca10(PO4)6X2, X being a fluorine, chlorine ion, or a hydroxyl group. HAp being the major inorganic component in natural bones crystallizes in hexagonal system. Synthetic HAp has the same chemical composition as biological HAp and mimics many properties of natural bone [1,2,3]. Synthetic HAp is limited in use due to high in vivo solubility and poor mechanical properties, such as low-impact resistance [4, 5]. The physical, chemical, and biological properties of HAp are controlled by its crystal structure and composition. The advantages of doping HAp with foreign elements pertinent to orthopedic applications were reported by others. Webster et al [9] reported that the Bi3+ would be the best choice of dopant to enhance properties of HAp pertinent for bone implant applications

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