M.Sc Thesis


M.Sc StudentYuri Melman
SubjectConstruction and Characterization of System for Electrical
Measurement with Temperature Control
DepartmentDepartment of Chemical Engineering
Supervisor Professor Tsur Yoed


Abstract

Impedance spectroscopy is widely used for characterization of the broad spectrum of dielectric materials in solid state, such as: electroceramics, polymers, nano-phase ceramics, and more. The most important advantage of this measurement is its ability to resolve the electrical responses of the different micro structural regions (e.g., electrode, grain boundaries, bulk) within the sample.

While analyzing impedance spectroscopy results, the main problem is to attribute a reasonable model that corresponds to elements of the microstructure. Correct interpretation relies on obtaining accurate data over wide frequency, impedance and temperature ranges. The measurement process is often complicated by experimental artifacts that make one wonder whether the measurements describe the sample or perhaps the experimental setup. They are arising from apparatus contribution (leads, sample holder), electrode contact effect, terminal configuration, measurement instrument limitations and other aspects.

 A system has been developed for measuring the electric properties of ceramic and other solid dielectric materials at frequencies from 0.001 to at least 106 Hz and over a temperature range of 85-1050K. It is capable of working with different measurement devices (e.g., impedance analyzer, lock-in amplifier). Special attention was paid to use non-expensive materials and cooling agent. The ability to work at as low as 85K using liquid nitrogen as cooling agent rather than liquid helium, is due to the fact that one of the electrodes in this system is connected to the body of the cryostat without insulation.