NASA Technical Reports Server (NTRS) : Refractory pdf

NASA Technical Reports Server (NTRS) : Refractory

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Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT 1 is realizable. These materials are divided into two classes: (1) the rare-earth chalcogenides which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (2) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity

• Creator/s: NASA Technical Reports Server (NTRS
• Date: 1/1/1983
• Year: 1983
• Book Topics/Themes: NASA Technical Reports Server (NTRS), ENERGY CONVERSION EFFICIENCY, REFRACTORY MATERIALS, THERMOELECTRIC MATERIALS, BORIDES, CHALCOGENIDES, DOPED CRYSTALS, HIGH TEMPERATURE, SEMICONDUCTORS (MATERIALS), THERMAL CONDUCTIVITY, Wood, C., Emin, D

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