Electrical Resistivity of Nickel, Cobalt and Their Alloys

Abstract

The electrical resistivity of nickel, cobalt and their alloys has been measured in the temperature range from 4.2 to 1600K. By using the s-d exchange-interaction constant and the numbers of conduction electrons and hole-carriers estimated in this study, the correlation between the magnetic resistivity and the ferromagnetism is discussed from the viewpoint of the scattering process due to the spin disorder containing not only the intraband s-s transition but also the interband s-d transition. It is pointed out that the hole-carrier, which is observed in the ordinary Hall effect or the resistivity due to the phonon scattering, plays a role of the probability of interband s-d transitions in the magnetic resistivity. In metals and alloys, the electrical resistivity sensitively reflects the magnetic property and the electronic structure. The first theoretical discussion on the electrical resistivity of ferromagnetic metals has been given by Mott(1). According to him, the resistivity of a ferromagnetic metal such as nickel is caused by transitions in which the electrons jump from the s-to the d-band mainly by phonon scattering, so at low temperatures only half the electrons can make such transitions, namely those with spin antiparallel to the spontaneous magnetization, because all levels in the d-band with spin parallel to the spontaneous magnetization are occupied. At high temperatures above the Curie temperature (T>Tc), the electrons with either spin direction can make transitions of this type.Kasuya (2) and de Gennes and Friedel(3) have calculated the electrical resistivity due to the sd exchange interaction in ferromagnetic metals and have given an alternative explanation for the magnetic resistivity apart from that given by Mott(1) on the basis of the band picture. The exchange interaction between the spin of the conduction electron and the spin (S) of unfilled inner shell electrons depends on the relative direction of both spins. They have found that the magnetic resistivity is zero at 0K, increases with increasing temperatures, in terms of the van Vleck model, where ci is the concentration of the constituent i-element, Pij and Sij are the fraction and the spin quantum number of the j-configuration of electron in the i-atom, respectively.The magnetic resistivity of some ferromagnetic and antiferromagnetic metals and alloys was explained(4) by this equation of the local-

High-temperature Resistant Interconnections Formed by Ni Nanoparticles/Al Micro-particles Composite Paste for SiC Power Device Application

“…In recent years, the low-temperature sintering bonding of Ag [13][14][15] and Cu [16,17] nanoparticles has been investigated and developed. However, some factors have limited the further application of Ag and Cu nanoparticles sintering, such as the low ion migration resistance of Ag [18,19] Previous studies have demonstrated that Ni nanoparticles smaller than 100 nm can function as a bonding material that can be sintered below 400°C and can exhibit higher long-term resistance to temperatures higher than 250°C. [20][21][22] A previous study reported that Ni nanoparticles can directly bond with Al in the atmosphere, even though Al does bond easily in soldering without flux processing.…”