The incorporation of europium into apatite: anew explanation

Abstract

Abstract Time resolved laser fluorescence spectroscopy (TRLFS) and X-ray absorption fine structure (XAFS) are used as complimentary techniques to show that the hetero-valent incorporation of europium into apatite at temperatures relevant to environmental and biological processes occurs at grain boundaries and not the crystallographic calcium sites as previously presumed. For this study, we focus on mechanisms at the solid solution interface and therefore define this temperature regime as the range in which liquid water exists (0–100 ºC). Site-selective TRLFS show that the local Eu3+ symmetry does not match the presumed crystallographic site of incorporation. This is confirmed by XAFS results that show a deviation from the local environment in apatite. The transition of this amorphous europium to acrystallographic calcium site upon heating is then explained by grain growth and followed through a transition species by TRLFS.