Luminescence properties of Eu2+ and Eu3+ doped calcium-deficient hydroxyapatite prepared in air

► The Eu-doped CDHA nanopowders with an average particle size of about 100 nm were successfully prepared using coprecipitation method and calcined at 600 °C for 2 h in air. ► The Eu3+ ions partly reduced to Eu2+ ions in the CDHA:Eu. ► Two non-equivalent Eu3+ sites labeled Eu1 (574.8 nm) and Eu2 (578.6 nm) were attributed to the substitution on Ca-II and Ca-I site respectively. ► The relationship between two spectroscopic sties, reduction of the Eu3+ ions with the defect microstructures, and the possible charge compensation mechanisms in the Eu-doped CDHA were detailed discussed.