Structural study of Yb3＋, Eu3＋ and Pr3＋ doped Ca9Lu（PO4）7

The whitlockite-like crystal structure of Ca9Lu（PO4）7 when doped with several ions （Yb3＋, EU3＋ and Pr3＋） at different concentrations （1 tool.%, 5 mol.% and 10 tool.%） was studied, by means of synchrotron X-ray diffraction. In particular for Eu3＋ and Pr3＋, the presence of the dopant ion significantly changed the occupation factors （OFs） of the Ca2＋ and Lu3＋ cations and gave rise to a distortion of the metal-oxygen polyhedra. The observed structural features clearly showed significant impact of the dopant ion on the crystal structure of the host.