Phonon-enhanced thermoelectric power of Y-Al-Ni-Co decagonal approximant
Zeitschrift Fur Kristallographie 224(1-2): 64-66
We have investigated anisotropic electrical resistivity and thermoelectric power of the ypsilon-phase Al-Ni-Co (Y-Al-Ni-Co) decagonal approximant with composition Al76Co22Ni2. The crystalline-direction-dependent measurements were performed along three orthogonal directions a*, b and c of the Y-Al-Ni-Co unit cell, where (a, c) monoclinic atomic planes are stacked along the perpendicular b direction. Anisotropic electrical resistivity is low in all crystalline directions, appearing in the order rho(a*) > rho(c) > rho(b) and showing positive temperature coefficient typical of electron-phonon scattering mechanism. Thermopower shows electron-phonon enhancement effect. Anisotropic bare thermopower (in the absence of electron-phonon interactions) was extracted, appearing in the same order as the resistivity, vertical bar S-a*(bare)/T vertical bar > vertical bar S-c(bare)/T vertical bar > vertical bar S-b(bare)/T vertical bar.