STRUCTURE INVESTIGATIONS ON HALIDE GLASSES (MnF2)x(BaCl2)100-x WITH THE EXAFS AND WAXS TECHNIQUES

Abstract

A short range structure investigation of halide glasses (MnF2)x(BaCl2)100-x(x = 65, 60, 55) has been made using the extended X-ray absorption fine structure (EXAFS) and the wide angle X-ray scattering (WAXS) techniques. The local structure information around the Mn is derived from the study of the MnK absorption edge EXAFS and the X-ray scattering intensity of the materials, respectively. The results show that the F and Cl atoms in the first neighbour shell of the Mn atom construct a octahedra (MnCl2F4) with the bond-length rMn-Cl = 0.246 nm and rMn-F= 0.200 nm in the glass of x = 65, which share the atom F with the neighbouring one to form zigzag chains linked by Ba atoms distributed between them. With decreasing of the amount of MnF2 below x = 65, the bond-length rMn-Cl and the Debye-Waller factor σMn-Cl2 of Mn-Cl increase, and that of Mn-F is almost invariant. The disappearance of the Mn-Mn peak has been found from x = 60 to x = 55 with an abrupt increase in rMn-Cl and σMn-Cl2, which can be explained as the chains being broken to form the solitude octahc-dra (MnCl2F4).