Nature of ThF bonding in crystalline and glassy states using EXAFS and XANES

A binary glass of thorium and hafnium tetrafluorides (with dopant concentrations of LaF3) has been investigated using EXAFS and XANES analysis of the LIll edge spectra of thorium. Results of EXAFS analysis indicate that there is no change in the number of nearest neighbors of thorium ions. However, the intensity of the white line in XANES is significantly higher in the glass. This increase in intensity has been explained semiquantitatively in terms of enhanced covalency of ThF bonding. Since the coordination number of Th4+ remains constant in both crystalline and glassy states, covalency enhancement seems to be a general characteristic of glassy state of ionic materials. © 1984.