Tatsuya Okada

Electrical properties of liquid Ni–Se and Cu–Se alloys

Abstract The electrical conductivities, σ, of liquid Cu–Se and Ni–Se alloys on the Se-rich side increase on the addition of Cu and Ni, respectively. The σs obtained at 1373 K are 1400, 5000, 4130 and 1920 Ω−1 cm−1 for liquid CuSe, NiSe, CoSe and FeSe, respectively. The thermoelectric power, S, of liquid Cu–Se alloys shows a p–n transition near the stoichiometric composition Cu2Se. The Ss obtained at 1373 K are 70 and 4 μV/K for liquid CuSe and NiSe, respectively. The large values of σ for liquid transition metal–Se alloys are related to the density of d-like states at the Fermi level due to the p–d hybridization.

Electrical properties of molten AgCl-AgI mixtures

Abstract The composition dependence of electrical conductivity, σ, for molten AgCl–AgI mixtures decreases monotonously on addition of AgI to molten AgCl. The activation energy, E1, estimated from a plot of ln σT versus 1/T is about 0.11 eV for their mixtures. The thermoelectric power, S, of their mixtures increases with increasing temperature. The slope of line in a plot of S versus 1/T changes at temperatures between 380°C and 450°C. The heat of transport, Q*, lies in the range from 0.07 to 0.18 eV at higher temperatures. The relatively large Q* of about 0.4 eV is found in the eutectic region at the lower temperatures.

Electrical properties of liquid Te–RE (RE = Ce, Sm, Er) alloys

Abstract When Ce, Sm and Er are added to liquid Te, the electrical conductivity, σ, and the thermoelectric power, S, of the liquid alloys are observed to decrease rapidly and to increase gradually, respectively, with increasing RE (RE=Ce, Sm, Er) composition. The composition dependences of σ in liquid Te–Ce, Te–Sm and Te–Er all approach zero at the stoichiometry RE2Te3. The similar composition dependences of σ suggest that the 4f electrons of the RE ions weakly interact with the conduction electrons. The σ and S of liquid Te–RE alloys are analyzed by the pseudogap model of liquid semiconductors. According to this model, the density of states, N(EF), at the Fermi level decreases smoothly with increasing RE composition and its gradient value, dN(EF)/dE, is weakly dependent on the RE composition.

The electrical conductivity and thermopower of liquid Ag1 − cSec alloys with 0.4 ≤ c ≤ 1.0

Abstract Measurements of the electrical conductivity and thermopower of liquid Ag1 − cSec alloys have been extended to the composition range c ≥ 0.4 by using an argon over pressure of 10 bar to prevent vaporisation of the Se. The composition dependence of the conductivity exhibits a minimum and a broad maximum near the compositions c = 0.4 and 0.65, respectively. The corresponding thermopower data show a p-n transition at c = 0.36. The data have been analysed using equations derived from the Kubo-Greenwood expressions.

Electrical properties of liquid Au-Si alloys

Abstract The electrical resistivity increases rapidly with the addition of Si to liquid Au, and the composition dependence of the electrical resistivity of liquid Au1−cSic alloys exhibits a maximum at the composition c=0.5. The composition dependence of the thermoelectric power of liquid Au1−cSic alloys shows a rapid change from a positive value on the Au side to a negative value in the composition range c ≧ 0.15 and reaches a minimum of −4 μV/K at the composition c=0.5. The electrical resistivity and the thermoelectric power of liquid Au–Si alloys have been estimated by the Faber–Ziman theory.

Electrical properties of liquid NiTe alloys with Ni halides

Abstract Liquid NiTe has a large electrical conductivity of 5700 Ω −1 xa0cm−1 at the melting point. The decrease in the conductivity on the NiTe side is about 140 and 230 Ω −1 xa0cm−1 with the addition of 1 mol% NiCl2 and NiI2, respectively. Liquid NiTe and molten NiI2 were found to be miscible in all proportions. Molten NiI2 has a conductivity of 35 Ω −1 xa0cm−1 at 950 °C. The electrical conductivity on the NiI2 side increases gradually with the addition of NiTe. The composition dependence of the thermoelectric power of molten NiTe–NiI2 mixtures increases gradually from −3 μV/K on the NiTe side to 37.5 μV/K on the NiI2 side. The composition dependence of the conductivity and thermoelectric power for molten NiTe–NiI2 mixtures was analyzed by electronic model of liquid semiconductors.

Electrical properties of liquid Ag-S and In-S alloys

Abstract Measurements of electrical conductivity ( σ ) and thermoelectric power ( S *) were made on liquid In 1− c S c with c xa0⩽xa00.6. The decrease in the composition dependence of σ on the M-rich (M=Ag, In) sides of liquid In–S and Ag–S is discussed in terms of the nearly free electron model. In the range of composition (60 at.% S) where the conductivity minimum frequently occurs, the composition dependence of σ for liquid In–S alloys has a maximum similar to that of the liquid Ag–S system. The S * for liquid In 2 S 3 is −192xa0±xa010 μV/K at the melting point. The σ and S * for liquid Ag–S and In–S alloys near the stoichiometry were analysed by using the equations derived from the Kubo–Greenwood formula.

Electronic properties of liquid Si−Se alloys

Copyright (c) 1996 Elsevier Science B.V. All rights reserved. The magnetic susceptibility of the liquid Si 1−c Se c system has been measured for c≥0.5. A broad minimum is observed at the composition c=2/3. The corresponding measurements of the electrical conductivity show a deep minimum at the composition c=0.6. Liquid Si 1−c Se c alloys with c≥0.5 have large positive values of thermo-electric power. The conductivity and thermopower near the stoichiometric composition SiSe 2 were analyzed by assuming an energy-dependent conductivity in the Kubo-Greenwood expressions. The value of conductivity gap was found to be 1.3 eV at 1373 K for liquid SiSe 2 .