Electrical impedance characterization of microporous films at elevated temperatures with interdigitated design

A new high temperature four point electrical measurement system was built in order to facilitate electrical impedance measurements on zeolite microporous materials over wide temperature and frequency ranges and particularly in vacuum and gaseous environments. The latter feature is important in sensing applications for microporous materials. Electrochemical impedance spectroscopy (IS) is a measurement technique that treats the sample under measurement as the dielectric in a capacitor. A central component of the system built in this work is an interdigitated planar capacitor (IDC) which was designed so that a large surface area of the material may be exposed to a changing environment. These IDCs were fabricated by combining a photolithographic 'liftoff' technique and Electron Beam Physical Vapor Deposition. Measurements were taken on the zeolite ZSM-5 and its hydrogen counterpart H-ZSM-5.