Characterization and Luminescence of Eu3+- and Gd3+-Doped Hydroxyapatite Ca10(PO4)6(OH)2

Abstract

Luminescence properties of europium-doped Ca10-xEux(PO4)6(OH)2 (xEu = 0, 0.01, 0.02, 0.10 and 0.20) and gadolinium-doped hydroxyapatite Ca9.80Gd0.20(PO4)6(OH)2 (HA), synthesized via solid-state reaction at T = 1300 °C, were investigated using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), and luminescence spectroscopy. Crystal structure characterization (from unit cell parameters determination to refined atomic positions) was achieved in the P63/m space group. FTIR analyses show only slight band shifts of (PO4) modes as a function of the rare earth concentration. Structural refinement, achieved via the Rietveld method, and luminescence spectroscopy highlighted the presence of dopant at the Ca2 site. Strong luminescence was observed for all Eu- and Gd-doped samples. Our multi-methodological study confirms that rare-earth (RE)-doped synthetic hydroxyapatites are promising materials for bio-imaging applications.

Neutron and XRD Single-Crystal Diffraction Study and Vibrational Properties of Whitlockite, the Natural Counterpart of Synthetic Tricalcium Phosphate

“…TPCs are biomaterial particularly wanted for their biocompatibility in human biosystem [1], and for the possibility of different cation replacements at the sites typically occupied by Ca [11], giving rise to different products, employed as commercial cement and paste for bone replacement [13,14]. In this regard, they are preferred to the more common synthetic Ca 10 (PO 4 ) 6 (OH) 2 hydroxyapatite because of their brittle nature [15,16]. Recently, additional interest has been also devoted to a series of rare-earth-doped TCP that are largely investigated as possible optical materials for biosciences application [10,11,17].…”

Synthesis of Gd+3 doped hydroxyapatite ceramics: optical, thermal and electrical properties

“…The vibronic intensity seen in the RE ions such as Gd 3+ doped HAp is due to vibronically induced forced electric dipole transitions [34]. In the literature, Paterlini et al said that the type of vibronic sidebands seen in the Gd 3 + doped HAp was observed for the first time only in their own study [30]. The vibronic peaks seen in the emission spectrum of Gd 3+ doped HAp belong to Gd-O, PO 3À 4 and O-H ions.…”

“…The luminescence of Gd 3+ in host materials is not so diverse because Gd 3+ has a certain transition which is 6 P 7/2 -8 S 7/2 . It is well known that the Gd-doped HAp samples show strong UV luminescence and that the excitation and the emission spectra of the Gd-doped HAp displays narrow peaks as in 4 f-4 f transitions [30].…”

“…x Gd x (PO 4 ) 6 (OH) 2 , and there was trace amount of Gd +3 in HAp structure. In addition, the non-emitting of the materials synthesized with different Gd +3 additive ratios indicates that the luminescence intensity is independent of Gd +3 amount [30].…”

“…As can be seen in Table 4, electrical resistance decreases as the Gd 3+ doping increases. This is thought to be due to the formation of Ca 2+ vacancies as a result of the replacement of the divalent Ca 2+ cations by trivalent Gd 3+ cations in the synthesized material [30]. Based on the literature on the subject, it is stated that the total electrical conductivity is the sum of the electrical and ionic conductivities.…”