In situ neutron scattering study of nanoscale phase evolution in PbTe-PbS thermoelectric material

Journal Article · Mon Aug 22 00:00:00 EDT 2016 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4961677· OSTI ID:22590519

Ren, Fei; Qian, Bosen ^[1]; Schmidt, Robert; Case, Eldon D. ^[2]; Keum, Jong K.; Littrell, Ken C.; An, Ke ^[3]

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1. Department of Mechanical Engineering, Temple University, Philadelphia, Pennsylvania 19122 (United States)
2. Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824 (United States)
3. Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States)

Introducing nanostructural second phases has proved to be an effective approach to reduce the lattice thermal conductivity and thus enhances the figure of merit for many thermoelectric materials. Studies of the formation and evolution of these second phases are essential to understanding material temperature dependent behaviors, improving thermal stabilities, as well as designing new materials. In this study, powder samples of the PbTe-PbS thermoelectric material were examined using in situ neutron diffraction and small angle neutron scattering (SANS) techniques between room temperature and elevated temperature up to 663 K, to explore quantitative information on the structure, weight fraction, and size of the second phase. Neutron diffraction data showed that the as-milled powder was primarily a solid solution prior to heat treatment. During heating, a PbS second phase precipitated out of the PbTe matrix around 500 K, while re-dissolution started around 600 K. The second phase remained separated from the matrix upon cooling. Furthermore, SANS data indicated that there are two populations of nanostructures. The size of the smaller nanostructure increased from initially 5 nm to approximately 25 nm after annealing at 650 K, while the size of the larger one remained unchanged. This study demonstrated that in situ neutron techniques are effective means to obtain quantitative information on temperature-dependent nanostructural behavior of thermoelectrics and likely other high-temperature materials.

• OSTI ID: 22590519
• Journal Information: Applied Physics Letters, Vol. 109, Issue 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANNEALING
APPROXIMATIONS
DISSOLUTION
HEATING
LEAD SULFIDES
LEAD TELLURIDES
NANOSTRUCTURES
NEUTRON DIFFRACTION
PERFORMANCE
SMALL ANGLE SCATTERING
SOLID SOLUTIONS
STABILITY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
THERMAL CONDUCTIVITY
THERMOELECTRIC MATERIALS