Thin film BCZT in a capacitive thermo-electric converter

• Main Author: Thomson, Emily (Emily S.)
• Other Authors: Yang Shao-Horn.
• Format: Others
• Language: English
• Published: Massachusetts Institute of Technology 2016
• Subjects: Materials Science and Engineering.
• Online Access: http://hdl.handle.net/1721.1/104146

Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, June 2016. === This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. === Cataloged from student-submitted PDF version of thesis. === Includes bibliographical references (page 35). === Thin film BCZT was processed, optimized, and analyzed from powder to ceramic to film for use in a capacitive thermos-electric converter. The idea of using a temperature dependent dielectric to turn heat into electricity has been around for several decades but has never been feasible due to low efficiency and the practical difficulty of being able to thermally cycle the dielectric material quickly enough. However, thin film materials are able to be thermally cycled at high enough frequencies. One material that has potential to be used as the dielectric in a capacitive thermo-electric converter is Ba(TixZr1-x)O3-(BayCa1-y)TiO3. Known as BCZT, this perovskite has previously been studied as an alternative to piezo electrics which are traditionally made with lead. BCZT has a very high dielectric constant of several thousand and, because of its triple point just above room temperature, the dielectric constant is temperature dependent around room temperature. In this paper, BCZT is studied for its potential as a thin film dielectric material in a capacitive thermo-electric converter. Several different compositions around the triple point are created from powder sources, sintered into targets for PLD, analyzed, and the most promising composition was deposited into a thin film and patterned with in-plane capacitor contacts. Analysis using XRD and dielectric measurements was done at several stages. === by Emily Thomson. === S.B.