Date of Award

12-2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Physics

Advisor

Tritt, Terry M

Committee Member

He , Jian

Committee Member

Drymiotis , Fivos

Abstract

With ever increasing energy costs, dwindling resources, and terms with the prefix 'green' filling headlines, the need for environmentally friendly energy sources has never been greater. Since the mid-20th century researchers have been pursuing greater efficiency in thermoelectric materials. Thermoelectric materials achieve energy conversion via the Seebeck effect (heat to electric power) and the Peltier effect (electricity to cooling power). Presented herein are the measured electrical and thermal transport properties and phenomenal analysis of the Ir3Ge7-type system: X0.05Mo3Sb7-yTey (X=Mn, Fe, Ni, Co; y=1.5, 1.6, 1.7) where 'X' are interstitially doped metal ions. First, the effect of the substitution ratio of Te was studied in the Fe subsystem. Te, having one more electron than Sb, decreases carrier concentration as Mo3(Sb,Te)7 has been observed to be p-type. Because of the decrease in the majority charge carrier, it is expected that both the Seebeck coefficient and resistivity will increase with tellurium content. Holding y=1.6 and varying the transition metal ion atomic number allowed for an analysis of the effectiveness of the dopants as a means to lower thermal conductivity. A prediction of the effect of dopant atomic number on thermal conductivity is not possible as too many factors come into play, such as bond strength between the dopant and parent matrix and atomic radius of the dopant.

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