Optical absorption of AlF3-YF3-PbF2-MF2-MgF2 (M= Ca, Sr and Ba) glasses doped with chromium ions

Fluoroaluminate glasses in the AlF3-YF3-PbF2-CaF2-MgF2, AlF3-YF3-PbF2-SrF2-MgF2 and AlF3-YF3-PbF2-BaF2-MgF2 systems have been doped with 0.2 and 0.3 mol % CrF3 and their optical absorption has been studied. The absorption spectrum displays two strong and broad bands corresponding to the electronic transitions (4)A(2g), (F-4) double right arrow T-4(2g) (F-4) and (4)A(2g) (F-4) double right arrow T T-4(1g) (F-4) of the Cr3+ ions in a nearly octahedral environment. Crystal field and Raccah parameters were determined. They depend on the nature of the earth alkali cation and also on chromium concentration, which suggests that local field and covalent character also change.