title: Improving thermoelectric performance of TiNiSn by mixing MnNiSb in the half-Heusler structure.
abstract: The thermoelectric properties of the n-type semiconductor TiNiSn were optimized by partial substitution with metallic MnNiSb in the half Heusler structure. Herein, we study the transport properties and intrinsic phase separation in the Ti1-xMnxNiSn1-xSbxsystem. The alloys were prepared by arc-melting and annealed at temperatures obtained from differential thermal analysis and differential scanning calorimetry results. The phases were characterized using powder X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and differential scanning calorimetry. After annealing, the majority phase was TiNiSn with some Ni-rich sites, and the minority phases were primarily Ti6Sn5, Sn and MnSn2. The Ni-rich sites were caused by Frenkel defects; this led to metal-like behavior in the semiconductor specimens at low temperature. For x ≤ 0.05 the samples showed an activated conduction, whereas for x > 0.05 they showed metallic character. The figure of merit for x = 0.05 was increased by 61% (zT = 0.45) in comparison with the pure TiNiSn.
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany. Gerhard.Fecher@cpfs.mpg.de.
authors.forename: T
authors.initials: T
authors.lastname: Berry
authors.affiliation: Johannes Gutenberg University Mainz, Staudingerweg 9, 55128 Mainz, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Ouardi
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany. Gerhard.Fecher@cpfs.mpg.de.
authors.forename: G H
authors.initials: GH
authors.lastname: Fecher
authors.affiliation: Johannes Gutenberg University Mainz, Staudingerweg 9, 55128 Mainz, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Balke
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany. Gerhard.Fecher@cpfs.mpg.de.
authors.forename: G
authors.initials: G
authors.lastname: Kreiner
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany. Gerhard.Fecher@cpfs.mpg.de.
authors.forename: G
authors.initials: G
authors.lastname: Auffermann
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany. Gerhard.Fecher@cpfs.mpg.de.
authors.forename: W
authors.initials: W
authors.lastname: Schnelle
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany. Gerhard.Fecher@cpfs.mpg.de.
authors.forename: C
authors.initials: C
authors.lastname: Felser