Ba. Cook et Jl. Harringa, Electrical and thermal properties of hot pressed (Nd0.5Gd0.5)Se1.50-x, where x=0.01, 0.02, J APPL PHYS, 90(10), 2001, pp. 5187-5195
Rare earth selenides, based on the composition (Nd0.5Gd0.5)Se1.50-x where 0
.005 less than or equal tox less than or equal to0.030, were prepared by va
por phase reaction, melting, and hot pressing. The transport properties of
electrical resistivity, Seebeck coefficient, and thermal diffusivity were c
haracterized between 300 and 1300 K. In addition, carrier concentration and
mobility were measured at 300 K. Chemical composition and homogeneity were
determined on several samples by electron microprobe and atomic emission s
pectroscopy. Partial substitution of Nd for Gd was found to stabilize the h
igh temperature gamma (Th3P4-type) phase. This system is characterized by a
low thermal conductivity, the temperature dependence of which indicates mi
xed scattering. Analysis of the Seebeck and carrier concentration data by a
single band conduction model suggests the existence of a heavy electron ba
nd, responsible for the large thermopower in this system. Electrical resist
ivity and Seebeck coefficient data were combined in a Jonker analysis to de
termine a maximum power factor, (S-2/rho), of 5.4 muW/cm degrees C2, corres
ponding to a resistivity of 5.5 Omega cm and a Seebeck coefficient of -172.
3 muV/degreesC. (C) 2001 American Institute of Physics.