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Title: Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds

Abstract

The 18-electron ternary intermetallic systems TiNiSn and TiCoSb are promising for applications as high-temperature thermoelectrics and comprise earth-abundant, and relatively nontoxic elements. Heusler and half-Heusler compounds are usually prepared by conventional solid state methods involving arc-melting and annealing at high temperatures for an extended period of time. Here, we report an energy-saving preparation route using a domestic microwave oven, reducing the reaction time significantly from more than a week to one minute. A microwave susceptor material rapidly heats the elemental starting materials inside an evacuated quartz tube resulting in near single phase compounds. The initial preparation is followed by a densification step involving hot-pressing, which reduces the amount of secondary phases, as verified by synchrotron X-ray diffraction, leading to the desired half-Heusler compounds, demonstrating that hot-pressing should be treated as part of the preparative process. For TiNiSn, high thermoelectric power factors of 2 mW/mK{sup 2} at temperatures in the 700 to 800 K range, and zT values of around 0.4 are found, with the microwave-prepared sample displaying somewhat superior properties to conventionally prepared half-Heuslers due to lower thermal conductivity. The TiCoSb sample shows a lower thermoelectric figure of merit when prepared using microwave methods because of a metallic second phase.

Authors:
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  1. (CIT)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - BASIC ENERGY SCIENCES
OSTI Identifier:
1045696
Resource Type:
Journal Article
Journal Name:
Chem. Mater.
Additional Journal Information:
Journal Volume: 24; Journal Issue: (13) ; 07, 2012; Journal ID: ISSN 0897-4756
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANNEALING; HOT PRESSING; MICROWAVE OVENS; PERFORMANCE; POWER FACTOR; QUARTZ; SYNCHROTRONS; SYNTHESIS; THERMAL CONDUCTIVITY; X-RAY DIFFRACTION

Citation Formats

Birkel, Christina S., Zeier, Wolfgang G., Douglas, Jason E., Lettiere, Bethany R., Mills, Carolyn E., Seward, Gareth, Birkel, Alexander, Snedaker, Matthew L., Zhang, Yichi, Snyder, G. Jeffrey, Pollock, Tresa M., Seshadri, Ram, Stucky, Galen D., and UCSB). Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds. United States: N. p., 2012. Web. doi:10.1021/cm3011343.
Birkel, Christina S., Zeier, Wolfgang G., Douglas, Jason E., Lettiere, Bethany R., Mills, Carolyn E., Seward, Gareth, Birkel, Alexander, Snedaker, Matthew L., Zhang, Yichi, Snyder, G. Jeffrey, Pollock, Tresa M., Seshadri, Ram, Stucky, Galen D., & UCSB). Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds. United States. doi:10.1021/cm3011343.
Birkel, Christina S., Zeier, Wolfgang G., Douglas, Jason E., Lettiere, Bethany R., Mills, Carolyn E., Seward, Gareth, Birkel, Alexander, Snedaker, Matthew L., Zhang, Yichi, Snyder, G. Jeffrey, Pollock, Tresa M., Seshadri, Ram, Stucky, Galen D., and UCSB). Thu . "Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds". United States. doi:10.1021/cm3011343.
@article{osti_1045696,
title = {Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds},
author = {Birkel, Christina S. and Zeier, Wolfgang G. and Douglas, Jason E. and Lettiere, Bethany R. and Mills, Carolyn E. and Seward, Gareth and Birkel, Alexander and Snedaker, Matthew L. and Zhang, Yichi and Snyder, G. Jeffrey and Pollock, Tresa M. and Seshadri, Ram and Stucky, Galen D. and UCSB)},
abstractNote = {The 18-electron ternary intermetallic systems TiNiSn and TiCoSb are promising for applications as high-temperature thermoelectrics and comprise earth-abundant, and relatively nontoxic elements. Heusler and half-Heusler compounds are usually prepared by conventional solid state methods involving arc-melting and annealing at high temperatures for an extended period of time. Here, we report an energy-saving preparation route using a domestic microwave oven, reducing the reaction time significantly from more than a week to one minute. A microwave susceptor material rapidly heats the elemental starting materials inside an evacuated quartz tube resulting in near single phase compounds. The initial preparation is followed by a densification step involving hot-pressing, which reduces the amount of secondary phases, as verified by synchrotron X-ray diffraction, leading to the desired half-Heusler compounds, demonstrating that hot-pressing should be treated as part of the preparative process. For TiNiSn, high thermoelectric power factors of 2 mW/mK{sup 2} at temperatures in the 700 to 800 K range, and zT values of around 0.4 are found, with the microwave-prepared sample displaying somewhat superior properties to conventionally prepared half-Heuslers due to lower thermal conductivity. The TiCoSb sample shows a lower thermoelectric figure of merit when prepared using microwave methods because of a metallic second phase.},
doi = {10.1021/cm3011343},
journal = {Chem. Mater.},
issn = {0897-4756},
number = (13) ; 07, 2012,
volume = 24,
place = {United States},
year = {2012},
month = {10}
}