Transport Properties of 40% La Filled Skutterudite Thin Films Sample Preparation and Data Analysis
The efficiency of thermoelectric energy conversion devices is a function of the thermoelectric figure of merit ZT where T is the absolute temperature and Z is defined as Z = S2?/?. Large values of ZT require high Seebeck coefficient S, high electrical conductivity ?, and low thermal conductivity ?. It is difficult to increase Z in bulk thermoelectric material because these three material's properties are coupled to each other.
In this project we studied thin skutterudite films. In order to measure the figure of merit we used a method (Harman's method) of measuring both adiabatic and isothermal voltages across the sample. A fraction of the conduction heat current flows through the glass substrate as well as through the thin film sample. The heat conductivity through the substrate is directly proportional to its thickness. The key idea of this study is to determine the relationship between the experimental figure of merit and the substrate thickness at constant temperature, thus obtaining the limiting Figure of Merit value for skutterudite thin films.
We obtained an average value of 18.901.43, which is higher than bulk skutterudite. The lower dimensionality, the amorphous structure, and the higher Seebeck coefficient of thin films are possible causes of the higher value of the limiting F.O.M.
School:Bowling Green State University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:skutterudite thermoelectric thin film figure of merit
Date of Publication:01/01/2008