Microstructure and thermoelectric properties of p and n type doped β-FeSi2 fabricated by mechanical alloying and pulse plasma sintering

• Published in: Materials today : proceedings Vol. 8; pp. 531 - 539
• Main Authors: Dąbrowski, Franciszek, Ciupiński, Łukasz, Zdunek, Joanna, Kruszewski, Jakub, Zybała, Rafał, Michalski, Andrzej, Jan Kurzydłowski, Krzysztof
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2019
• Subjects: doping; iron disilicide; pulse plasma sintering; Seebeck effect; thermoelectricity; pulse plasma sintering; doping; iron disilicide; Seebeck effect; thermoelectricity
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2019.02.050

N and p type doped, β-FeSi2 was obtained by pulse plasma sintering (PPS) of mechanically alloyed Fe, Si with Mn, Co, Al, P as dopants. The consolidated samples were subsequently annealed at 1123K for 36ks. SEM observations proved that the samples consolidated by PPS preserve fine grain size of the mechanically alloyed β-FeSi2 and the low porosity. The results of XRD measurements confirmed for all samples a nearly complete transformation from α- and ε- into β-FeSi2 phase after annealing. Their thermal conductivity decreases significantly with the increase of the test temperature in the entire rage of the temperatures of practical meaning. With the exception of the Mn-doped, all samples exhibited a high Seebeck coefficient, with its highest value for FeSi1.95P0.05 exceeding -400μV/K up to 550K. The Mn and Co – Fe site dopants revealed a stronger effect on the thermoelectric properties with 0.15ZT parameter at 773K for Fe0.97Co0.03Si2 alloy. The thermoelectric properties of PPS sintered samples were compared to the previously reported consolidated by hot pressing and spark plasma sintering. It has been concluded that the pulse plasma sintering offers an alternative to the already explored methods of production of thermoelectric materials.