Fig. 5. ³¹Phosphorus magnetization recovery curves as a function of time for: (a) pure synthetic hydroxyapatite (SHA) and the mixture of MnSO₄·H₂O and pure-SHA (Mn-mix); (b) all the Metal-synthetic hydroxyapatites; and (c) Fe12-, Mn11-, and Cu12-SHA after being treated 4 h with DTPA.