Properties and structure of PbGeOF glasses

Abstract

New fluoride glasses in the xPbF2: (1-x)[PbO:GeO2] system have been synthesized and characterized. The physical properties such as the glass transition temperature (Tg), density, dc conductivity (σ) and activation energy are measured. The Tg has been found to go through a minimum as the PbF2 content increases. σ increases progressively with the increase in PbF2 content and reaches a maximum value of 6.76×10-7 (Omega cm)-1 at T= 573 K with activation energy = 1.19 eV in the sample for which x = 0.3. However, further increase of the PbF2 content does not have any noticeable effect on ionic transport. X-ray photoelectron spectroscopic (XPS) study reveals that the F 1s spectrum has two components. One of the component peaks at binding energy (BE) 683.4 eV has been attributed to fluorine in ionic PbF bonds, and the other, at BE 684.4 eV, to the fluorine in GeFPb bonds in accordance with single bond strength data. The changes in the XPS Ge 3d spectra also indicate two chemical states for Ge atoms. © 1992.