medium to high temperature thermoelectric materials
TRANSCRIPT
Single phase powders of CoSb3, CoSb2.85Te0.15 and Yb0.075CoSb2.85Te0.15 were obtained by mechanical alloying. Ceramic disk of 20 millimetre diameter were fabricated (relative density >97%) by Spark Plasma Sintering.
Electrical Conductivity and seebeck coefficient were measured using Namicro thermoelectric measurement equipment, under vacuum and thermal conductivity were measured using LFA 457, DSC and density measurement by Archimedes' Principle.
The objective of our research is to optimize thermoelectric properties of CoSb3 by using Phonon Glass Electron Crystal concept i.e. to reduce thermal conductivity without affecting electrical conductivity and seebeck coefficient.
Utilizing Waste Heat for Electricity Generation by Thermoelectrics‡
Jibran Khaliq1, Qinghui Jiang1, Haixue Yan1,2 Kevin Simpson3, and Michael J. Reece1,2
1School of Engineering and Material Science, Queen Mary University of London, London, E1 4NS, UK 2Nanoforce Technology Limited, London, E1 4NS, UK 3European Thermodynamics Limited, Leicester LE8 0RX, UK Email: [email protected], [email protected]
3. Objective
6. Conclusion
A very low thermal conductivity of 2.19 W/m.K was observed in Yb0.075CoSb2.85Te0.15 without affecting electrical conductivity and seebeck coefficient of CoSb2.85Te0.15. A high zT value of ~0.7 is reported for Yb doped and Te substituted CoSb3.
1. Motivation
5. Results and Discussions
Schematic of Spark Plasma Sintering (SPS) furnace
More than 60% heat is wasted while burning fuel. This waste heat can be utilized as a source of free energy. Thermoelectric materials can convert this waste heat from different sources directly into electricity. Thermoelectric materials are environmentally friendly, have no moving parts and are light weight, which make them excellent energy harvesting materials. Their efficiency is represented by dimensionless figure of merit zT which depends on high electrical conductivity and seebeck coefficient and low values of thermal conductivity.
School of Engineering and Materials Science
Mars Curiosity Rover: Powering itself through thermoelectric generator (Photo Credit: NASA/JPL-Caltech)
Acknowledgement
2. Applications
Cell phone charger: Uses heat from the feet
Thermoelectric generator in car: Uses heat from engine Thermoelectric Cooler
4. Materials and Methods
Sb was substituted for Te in CoSb3 (CoSb2.85Te0.15) to enhance electrical conductivity and seebeck coefficient.Two naturally formed cage in the crystal structure of CoSb3 was filled by Yb which ‘‘rattle’’ inside the cage to reduce thermal conductivity only.
Decrease in thermal conductivity with Yb addition in CoSb2.85Te0.15. No effect on electrical conductivity and seebeck coefficient. zT value increased to ~ 0.7.
CoSbYb
‡ Work Submitted to Scripta Materialia