Determination of the local electrical properties in ceramic materials gained by microcontact impedance spectroscopy

摘要: Abstract We used microcontact impedance spectroscopy with spatial resolution of about few micrometers to study the influence microstructure on electrical conductivity two selected ceramic materials: (I) polycrystalline AgBr highly conductive grain boundaries and well-known bulk properties (II) LiMn 2 O 4 –carbon black composite which is technological importance for lithium rechargeable batteries. In quantitative polycrystals we could easily separate from boundary conductance. found that followed behavior single crystals, while conductance exhibited activation energy in whole temperature range studied. Comparing results obtained by microimpedance conventional spectroscopy, showed brick layer model relates accurately local overall sample's if carbon coating was prepared controlled deposition dispersion, electronic higher than composites mixing. Microcontact shows former case distribution interfacial conductances (carbon black) much narrower explains percolation threshold observed already at very low fractions.