Luminescence in the LiF–MgF2 System Activated by Rare Earths

In recent years, several reports have appeared on luminescence in LiMgF 3 . Important applications have also been claimed. There is no record of LiMgF 3 in the ICDD database. In light of the crystallographic studies on ABF 3 compounds and especially the finding that LiMgF 3 is not formed, the reports on the LiMgF 3 based phosphors appear interesting. Our reinvestigation confirmed that LiMgF 3 does not exist. It is quite likely that the interesting properties described in the literature for LiMgF 3 , in fact, belong to the frozen eutectic or two-phase system. All the same, the existence of eutectic was exploited to melt MgF 2 at much lower temperature (735°C) than the melting point of MgF 2 (1263°C). We prepared LiF–MgF 2 :Eu 2+ and LiF–MgF 2 :Ce 3+ by melting at 735°C. These materials exhibited properties similar to those of MgF 2 :Eu 2+ and MgF 2 :Ce 3+ phosphors, respectively. Thus, using the lower melting point of eutectic, it might be possible to prepare various MgF 2 based phosphors at temperatures as low as 735°C, against the high melting point of 1263°C for MgF 2 .