Properties and structure of PbGeOF glasses

Abstract New fluoride glasses in the x PbF 2 : (1− x )[PbO:GeO 2 ] system have been synthesized and characterized. The physical properties such as the glass transition temperature ( T g ), density, dc conductivity (σ) and activation energy are measured. The T g has been found to go through a minimum as the PbF 2 content increases. σ increases progressively with the increase in PbF 2 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 PbF 2 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 PbF bonds, and the other, at BE 684.4 eV, to the fluorine in GeFPb bonds in accordance with single bond strength data. The changes in the XPS Ge 3d spectra also indicate two chemical states for Ge atoms.