TSDC and neutron scattering measurements on Ba1-xLaxF2+x and Ba1-xUxF2+2x solid solutions

A study was made of the dynamical behaviour of bound interstitial fluoride ions in disordered Ba1−xLaxF2+x and Ba1−xUxF2+2x solid solutions with Thermally Stimulated Depolarisation Current measurements and neutron scattering measurements, and a combination of both techniques. From 10 K to 400 K the TSDC spectra showed four reorientation peaks to be present in Ba1−xLaxF2+x, and six in Ba1−xUxF2+2x, along with the relaxation of the macroscopic space charge. The position of a space charge peak shifted to lower temperatures with increasing solute content. The dipolar realaxations were concentration invariant. In Ba1−xLaxF2+x neutral associates, L-shaped- and (222)- clusters occur. The present study reveals (212)-clusters to be present in Ba1−xUxF2+2x. The relations between ion dynamics and defect structures are discussed