Effect of Strontium on Luminescence Properties and Substitution Site of Eu doped Sr-Ca-Hydroxyapatite

Abstract

A series of Europium (Eu) and Strontium (Sr) codoped hydroxyapatite samples (Ca10-x-Srx-HAp: Eu) were designed and prepared using the chemical co-precipitation method. The crystalline structure, chemical composition and luminescent property of samples were characterized by X-ray diffraction (XRD) and photoluminescent spectrum (PL). XRD patterns showed that Eu doping had little effect on the structure of the samples, while with the increase of Sr content, crystallinity and interplanar crystal spacing were increased. PL spectra indicate that the fluorescence intensity at 596 nm and 618 nm of Ca-Sr-HAp: Eu samples increased firstly and then decreased with increase of Sr content at 394 nm excitation, and the strongest peak appeared in the Ca3-Sr7-HAp: Eu samples. At the same time, the fluorescence lifetime of the samples showed the same tendency with the increase of Sr content. In addition, the ratio of magnitude between electric dipole and magnetic dipole transition (IR/IO) also increased firstly and decreased subsequently along with the increase of Sr content in the matrix. Furthermore, the energy transfer 1104 无 机 材 料 学 报 第 31卷 parameters (f) calculated from luminescent dynamic of Eu correlating to different sites and transitions present the reverse change. It is concluded that the doped sites of Eu ions in the host lattice are affected by the content and location of Sr ions in the matrix. Thereby a tunable luminescent property of Ca10-x-Srx-HAp: Eu samples can be obtained by changing the site of Eu ions in the matrix through adjusting the value of Sr/Ca.