Time-domain electrostatic force spectroscopy on nanostructured lithium-ion conducting glass ceramics: analysis and interpretation of relaxation times

The nanoscopic electrical properties of LiAlSiO4 glass ceramics with different degrees of crystallinity chi were studied by means of time-domain electrostatic force spectroscopy (TDEFS). Thereby, a faster relaxation process due to lithium ion movements in the glassy phase and a slower process due to lithium ion movements in the crystallites could be distinguished. Over a broad range of crystallinity values, the TDEFS relaxation times of both processes are Arrhenius activated, with an activation energy being essentially independent of chi and with a pre-exponential factor depending in a systematic fashion on chi. With increasing crystallinity, the pre-exponential factor of the faster process (glassy phase) increases, while that of the slower process (crystallites) decreases. In order to explain this observation, we consider simple equivalent circuit models for the capacitance relaxation of the system AFM tip/gap/sample.