MeV Ion-Beam Bombardment Effects on The Thermoelectric Figures of Merit of Zn4Sb3 and ZrNiSn-Based half-heusler compound
- PDF / 168,732 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 71 Downloads / 219 Views
1020-GG07-09
MeV Ion-Beam Bombardment Effects on The Thermoelectric Figures of Merit of Zn4Sb3 and ZrNiSn-Based half-heusler compounds S. Budak1, S. Guner1, C. Muntele1, C. C. Smith2, B. Zheng1, R. L. Zimmerman1, and D. ILA1 1 Center for Irradiation of Materials, Alabama A&M University, 4900 Meridian Street, PO Box 1447, Normal, AL, 35762 2 MSFC, NASA, MSFC, Huntsville, AL, 35812 Abstract Semiconducting β-Zn4Sb3 and ZrNiSn-based half-heusler compound thin films were prepared by co-evaporation for the application of thermoelectric (TE) materials. High-purity solid zinc and antimony were evaporated by electron beam to grow the β-Zn4Sb3 thin film while highpurity zirconium powder and nickel tin powders were evaporated by electron beam to grow the ZrNiSn-based half-heusler compound thin film. Rutherford backscattering spectrometry (RBS) was used to analyze the composition and thickness of the thin films. The grown thin films were subjected to 5 MeV Si ions bombardment for generation of nanostructures in the films. We measured the thermal conductivity, Seebeck coefficient, and electrical conductivity of these two systems before and after 5 MeV Si ions beam bombardment. The two material systems have been identified as promising TE materials for the application of thermal-to-electrical energy conversion, but the efficiency still limits their applications. The electronic energy deposited due to ionization in the track of MeV ion beam can cause localized crystallization. The nanostructures produced by MeV ion beam can cause significant change in both the electrical and the thermal conductivity of thin films, thereby improving the efficiency. We used the 3ωmethod measurement system to measure the cross-plane thermal conductivity ,the Van der Pauw measurement system to measure the electrical conductivity, and the Seebeck-coefficient measurement system to measure the cross-plane Seebeck coefficient. The thermoelectric figures of merit of the two material systems were then derived by calculations using the measurement results. The MeV ion-beam bombardment was found to decrease the thermal conductivity of thin films and increase the efficiency of thermal-to-electrical energy conversion. Keywords: Ion bombardment, Thermoelectric properties, Rutherford backscattering spectrometry, Van der Pauw method, 3w method, Seebeck coefficient, Figure of merit *Corresponding author: D. ILA; Tel.: 256-372-5866; Fax: 256-372-5868; Email: [email protected]
1. INTRODUCTION Thermoelectric materials are very important due to the interest in their applications in thermoelectric power generation and microelectronic cooling [1]. Thermoelectric power
generation could convert heat to electricity directly. The ZrNiSn half-Heusler alloy is one of the potential candidates for the thermoelectric materials and has recently received great interest [2]. β-Zn4Sb3 with a complex hexagonal crystal structure has also been discovered to be one of the promising candidates for thermoelectric power generation applications [3]. Effectiveness of the thermoelectric mat
Data Loading...
