XAFS investigation of Cu(I) local environment in two types of glasses of base composition LaMgB5O10 and LiLaP4O12

X-ray absorption spectroscopy (XAFS) has been used to characterise the local environment around Cu+ ions in two types of glasses of base composition LaMgB5O10 and LiLaP4O12. In both glasses, Cu+ is surrounded by two oxygens respectively at 1.87 and 1.86 Angstrom For the first time in glasses, the formation of Cu+-Cu+ pairs (d(Cu-Cu) = 2.35 Angstrom) is clearly evidenced in the phosphate. These results will be discussed with respect to the crystal chemistry of Cu(I) in copper oxides and the specific luminescent properties of an isolated Cu+ centre or Cu+-Cu+ pairs. (C) 1997 Elsevier Science S.A.