Structural stability of the synthetic thermoelectric ternary and nickel-substituted tetrahedrite phases

[Display omitted] •Phase stability of tetrahedrite is addressed by DSC, XRD and neutron diffraction.•Effect of temperature, kinetic, and composition is discussed.•We report ZT=0.8 in highly dense samples (98%) sintered by SPS. The purity and structural stability of the high thermoelectric performanc...

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Bibliographic Details
Published in:Journal of alloys and compounds 2015-06, Vol.634, p.253-262
Main Authors: Barbier, Tristan, Lemoine, Pierric, Gascoin, Stéphanie, Lebedev, Oleg I., Kaltzoglou, Andreas, Vaqueiro, Paz, Powell, Anthony V., Smith, Ron I., Guilmeau, Emmanuel
Format: Article
Language:English
Subjects:
Chemical Sciences
Cristallography
High resolution
High temperature characterization
Material chemistry
Neutron powder diffraction
Nickel
Operating temperature
or physical chemistry
Phases
Powder X-ray diffraction
Purity
Spark plasma sintering
Structural stability
Tetrahedrite
Theoretical and
Thermoelectric compound
Thermoelectricity
Transmission electron microscopy
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Summary:[Display omitted] •Phase stability of tetrahedrite is addressed by DSC, XRD and neutron diffraction.•Effect of temperature, kinetic, and composition is discussed.•We report ZT=0.8 in highly dense samples (98%) sintered by SPS. The purity and structural stability of the high thermoelectric performance Cu12Sb4S13 and Cu10.4Ni1.6Sb4S13 tetrahedrite phases, synthesized by solid–liquid–vapor reaction and Spark Plasma Sintering, were studied at high temperature by Rietveld refinement using high resolution X-ray powder diffraction data, DSC/TG measurements and high resolution transmission electron microscopy. In a complementary study, the crystal structure of Cu10.5Ni1.5Sb4S13 as a function of temperature was investigated by powder neutron diffraction. The temperature dependence of the structural stability of ternary Cu12Sb4S13 is markedly different to that of the nickel-substituted phases, providing clear evidence for the significant and beneficial role of nickel substitution on both sample purity and stability of the tetrahedrite phase. Moreover, kinetic effects on the phase stability/decomposition have been identified and discussed in order to determine the maximum operating temperature for thermoelectric applications. The thermoelectric properties of these compounds have been determined for high density samples (>98%) prepared by Spark Plasma Sintering and therefore can be used as reference values for tetrahedrite samples. The maximum ZT of 0.8 was found for Cu10.4Ni1.6Sb4S13 at 700K.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2015.02.045