Compositionally Graded V2O5 for Improved Thermoelectric Power
EMSL Project ID
19093
Abstract
Conversion of waste heat into useful energy in many applications including automobile exhausts has received considerable attention, recently. As such, there is a growing interest in synthesizing segmented thermoelements, tuned to specific temperature ranges, as thermoelectric materials over conventionally used heavy metal based materials due to its environmental friendliness. One of the main challenges facing in these materials is its poor heat to energy conversation efficiency. Concentration gradient of a dopant can be regarded as a continuously segmented thermoelement composed of a single parent material as opposed to multiple dissimilar materials. In this regard, compositional gradient is more advantageous in terms of material processing, and may result in better compatibility for device applications, especially for thin film application as gradient structures are relatively easy to produce. Recent experiments suggest that the thermoelectric parameters of oxide materials can be enhanced by controlling the "spin and/or configurational entropy". To this notion, we propose to develop material systems using concentration gradient of the dilute ferromagnetic spin-electric semiconducting materials (DMS), such as Co doped TiO2 in rutile phase and V205. In the proposed work, we will implant Ni ions in V205 films and characterize the films using various capabilities. Characterization of thin film materials is critical as it serves as feedback to improve the synthesis conditions and thermoelectric properties. These characterizations include X-ray photoelectron spectroscopy, Auger electron spectroscopy, Rutherford back scattering and Proton induced X-ray emission. We are particularly interested in utilizing a high energy ion implantation to incorporate Na ions into V2O5 lattice. By spatially implanting Na ions to the film, compositionally graded NaxV2O5 samples will be fabricated, and their thermoelectric transport property will be measured as a function of temperature. Applying magnetic field during the thermoelectric measurements, the d-state degeneracy for the V ion site can be removed, thus changing the entropy. We will study the effect of spin/configurational entropy.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2006-07-21
End Date
2007-10-08
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
A. Yamamoto, V. Shutthanandan2, L. Saraf, S. Thevuthasan, F.S.Ohuchi. "Thermoelectric Properties of graded Ni-dose TiO2 Thin films
prepared by Ion implantation Technique", Proc. 3rd meeting of Thermoelectric Society of Japan, Aug. 22, 2006 : 48-49