B10 - HD Dr. H. Bracht
Nanoscale conductivity spectroscopy on solid electrolytes using an atomic force microscope
Ion-conducting crystals, glasses, and polymers are widely used as solid electrolytes in batteries, fuel cells, and chemical sensors. A lot of research work is being carried out
in order to find materials with improved ionic conductivities. One method that is becoming more and more technologically relevant is nanostructuring of materials. It has,
for instance, been found that the ionic conductivity of nanocrystalline ionic conductors can be increased by adding nanocrystalline insulators. In the case of glasses, a
conductivity enhancement can be achieved by the formation of nanocrystallites during partial crystallization. Furthermore, the ionic conductivity of polymer electrolytes
can be improved considerably by incorporating nanoparticles, such as Al2O3, TiO2, and ZrO2, into the polymer
matrix. Up to now, there
is no general agreement about the origin of these conductivity enhancement effects. A limiting factor hindering a better theoretical understanding and thus a more
systematic preparation of improved materials is the traditional characterization of the ion dynamics by means of macroscopic techniques, such as conductivity
spectroscopy, tracer diffusion measurements, and NMR relaxation techniques. In nanostructured solid electrolytes, diffusion pathways in different phases and at interfaces
are believed to play an important role for the ion transport. Therefore, an experimental method capable of probing ion transport on nanometer length scales would be
highly desirable. We
report on the application of electrostatic force spectroscopy for studying ion transport in solid electrolytes and carried out time-domain electrostatic force spectroscopy on
two different ion-conducting glasses using an atomic force microscope. We compare the electrostatic force spectroscopic data obtained at different temperatures with
macroscopic electrical data of the glasses. The overall consistency of the data shows that electrostatic force spectroscopy is capable of probing the ion dynamics and
transport in nanoscopic subvolumes of the samples.
Drittmittelgeber:
Beteiligte Wissenschaftler:
Veröffentlichungen:
|