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

In this study, hydroxyapatite powder Ca10(PO4)6(OH)2 (HAp) doped with gadolinium (Gd3+) (HAp:Gd3+) in different mole percentage of between 0.1 and 1.6 was synthesized by sol−gel method at 900°C. The reaction was carried out by hydrolysis of Ca(OH)2 and DCPD (CaHPO4.2H2O) in aqueous solution and then analyzed through XRD, SEM, FTIR, TGA and Four-Point Probe method (custom-made). The results show that Gd3+ has been successfully doped into the hydroxyapatite structure. Then, the photoluminescence, thermal and electrical properties of pure and Gd3+ doped hydroxyapatite were studied and compared with the pure hydroxyapatite. In conclusion, the emission band of Ca10-xGdx(PO4)6(OH)2 was observed at 263, 278, 294, 312 nm) under excitation with 185 nm. The Stokes shift of HAp:Gd3+ was calculated to be 16.031 cm−1. On the other hand, the electrical and thermal conductivity of HAp increased with the increase in Gd3+ concentration due to Ca2+ cation vacancies caused by Gd3+doping.