Thermoelectric Properties of SiO 2 /SiO 2 +CoSb 3 Multi Nanolayered Films Modified by Me v Si ions Bombardment
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Thermoelectric Properties of SiO2/SiO2+CoSb3 Multi Nanolayered Films Modified by MeV Si Ions Bombardment S. Budak1, C. Smith2, J. Chacha1, M. Pugh1, K. Ogbara3, K. Heidary1, R. B. Johnson 3, C. Muntele2, D.ILA2 1
Department of Electrical Engineering, Alabama A&M University, Normal, AL USA 2 Center for Irradiation of Materials, Alabama A&M University, Normal, AL USA 3 Department of Physics, Alabama A&M University, Normal, AL USA Abstract
The performance of the thermoelectric devices and materials is shown by a dimensionless figure of merit, ZT = S2σT/K, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and K is the thermal conductivity. ZT can be increased by increasing S, increasing σ or decreasing K. We have prepared 100 alternating nanolayered films of SiO2/SiO2+CoSb3 using the ion beam assisted deposition (IBAD). The 5 MeV Si ions bombardments have been performed using the AAMU Pelletron ion beam accelerator to make quantum clusters in the nanolayered superlattice films at the three different fluences to decrease the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and cross plane electrical conductivity. We have characterized 100 alternating nanolayered films of SiO2/SiO2+CoSb3 before and after Si ion bombardments as we measured the cross-plane Seebeck coefficient, the cross-plane electrical conductivity, and the cross-plane thermal conductivity for three different fluences. *Corresponding author: S. Budak; Tel.: 256-372-5894; Fax: 256-372-5855; Email: [email protected] 1. INTRODUCTION Thermoelectric generator is a useful and environment friendly device for direct energy conversion. Especially the capacity of Peltier and Seebeck effect to dispense with the moving parts in the realm of energy transformation from heat to electricity and vice versa is more appealing in such devices [1]. Thermoelectric materials of skutterudite structure, which have a body-centered cubic (bcc) structure in space group Im3(T5h) and a AB3 formula, where A is Co, Rh or Ir and B is P, As or Sb, have been reported of promising thermoelectric properties [2]. Effective thermoelectric materials and devices have a low thermal conductivity and a high electrical conductivity [3]. The performance of the thermoelectric materials and devices is shown by a dimensionless Figure of Merit, ZT = S 2σT / κ , where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity [4]. ZT can be increased by increasing S, increasing σ, or decreasing κ. CoSb3-based skutterudite materials have been extensively studied for thermoelectric (TE) materials since it was singled out in 1995 as a prime example as a potentially high ZT material from Slack's proposed “phonon glass electron crystal” concept. Despite their favorable features such as high electron mobility and high Seebeck coefficient, which give skutterudites a high power factor, the undoped CoSb3based skutterudites are disadvantaged by th
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