A round Robin test of the uncertainty on the measurements of the thermoelectric dimensionless figure of merit of Co_0.97Ni_0.03Sb₃

Eric Alleno (1) , David Bérardan (2) , Céline Byl (2) , Christophe Candolfi (3) , Ramzy Daou (4) , Rodolphe Decourt (5) , Emmanuel Guilmeau (4) , Sylvie Hébert (4) , Jiří Hejtmánek (6) , Bertrand Lenoir (3) , Philippe Masschelein (3) , Viktoriia Ohorodniichuk (3) , Michaël Pollet (5) , Sascha Populoh (7) , Didier Ravot (8) , Olivier Rouleau (1) , Mathieu Soulier (9)

1 ICMPE - Institut de Chimie et des Matériaux Paris-Est
2 ICMMO - Institut de Chimie Moléculaire et des Matériaux d'Orsay
3 IJL - Institut Jean Lamour
4 CRISMAT - Laboratoire de cristallographie et sciences des matériaux
5 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
6 Institute of Physics [Prague]
7 EMPA Materials for Energy Conversion
8 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
9 LITEN - Laboratoire d'Innovation pour les Technologies des Energies Nouvelles et les nanomatériaux

A round robin test aiming at measuring the high-temperature thermoelectric properties was carried out by a group of European (mainly French) laboratories (labs). Polycrystalline skutterudite Co_0.97Ni_0.03Sb₃ was characterized by Seebeck coefficient (8 labs), electrical resistivity (9 labs), thermal diffusivity (6 labs), mass volume density (6 labs), and specific heat (6 labs) measurements. These data were statistically processed to determine the uncertainty on all these measured quantities as a function of temperature and combined to obtain an overall uncertainty on the thermal conductivity (product of thermal diffusivity by density and by specific heat) and on the thermoelectric figure of merit ZT. An increase with temperature of all these uncertainties is observed, in agreement with growing difficulties to measure these quantities when temperature increases. The uncertainties on the electrical resistivity and thermal diffusivity are most likely dominated by the uncertainty on the sample dimensions. The temperature-averaged (300–700 K) relative standard uncertainties at the confidence level of 68% amount to 6%, 8%, 11%, and 19% for the Seebeck coefficient, electrical resistivity, thermal conductivity, and figure of merit ZT, respectively. Thermal conductivity measurements appear as the least accurate. The moderate value of the temperature-averaged relative expanded (confidence level of 95%) uncertainty of 17% on the mean of ZT is essential in establishing Co_0.97Ni_0.03Sb₃ as a high temperature standard n-type thermoelectric material.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Eric Alleno, David Bérardan, Céline Byl, Christophe Candolfi, Ramzy Daou, et al.. A round Robin test of the uncertainty on the measurements of the thermoelectric dimensionless figure of merit of Co_0.97Ni_0.03Sb₃. Review of Scientific Instruments, 2015, 86 (1), 011301 (9 p.). ⟨10.1063/1.4905250⟩. ⟨hal-01108894⟩