Measurements of thermoelectric properties of identical Bi-Sb sample in magnetic fields and influence of sample geometry

• Published in: The Journal of the Thermoelectrics Society of Japan Vol. 20; no. 2; pp. 67 - 74
• Main Authors: Suzuki, Mari, Aoyama, Kayo, Yamamoto, Atsushi, Hasegawa, Yasuhiro, Komine, Takashi, Ohshima, Hironori, Nagase, Kazuo, Murata, Masayuki
• Format: Journal Article
• Language: Japanese
• Published: The Thermoelectrics Society of Japan 06.10.2023; 一般社団法人 日本熱電学会
• ISSN: 1349-4279; 2436-5068
• DOI: 10.50972/thermoelectrics.20.2_67

The influence of sample geometry on measured physical properties (the magneto-Seebeck effect, Nernsteffect, magnetoresistance effect, Hall effect, and thermal conductivity) in a magnetic field was investigated fora polycrystalline Bi-Sb sample. The polycrystalline Bi88Sb12 bulk sample was prepared using the spark plasmasintering method and annealing, and the physical properties obtained via measurements in magnetic fields of5 T were compared with the simulated values obtained by the finite element method with considering varioussample geometries. The appropriate shape required for the precise measurement of less than 2% error was foundto be different for each physical property: the required aspect ratio of length l to width w is l/w > 0.57 for the magnetoresistance effect, l/w > 2.9 for the Hall effect, l/w > 4.2 for the two-wire magneto-Seebeck effect, l/w > 1.2for the four-wire magneto-Seebeck effect, and l/w > 3.1 for the Nernst effect. We also found that a small error ofless than 2% in the thermal conductivity measurement requires Ks/Kw > 27, where Ks and Kw represent the thermalconductance of sample and that of lead wire, respectively.