Abstract
The change in the electronic specific heat of dilute alloys, especially iron with a small addition of solute elements, was investigated experimentally in order to understand the electronic band structure of transition elements in relation to the origin of ferromagnetism. Since we have to measure a small change (order of one or two percent) in the electronic specific heat with a small addition of the solute element, a special calorimeter, which is used to measure simultaneously the specific heat of three samples, one pure metal and two alloys, has been developed for this purpose. Using this calorimetry, the change of γ can be measured with higher accuracy in one order of magnitude. The solute elements for iron-based alloys are: Ti, V, Cr, Mn, Co, Ni, Nb, Mo, W, Si and Al. Silver-based alloys with gold are also measured to check the accuracy of this calorimeter. The variation of γ for Ag(Au) alloys is less than experimental uncertainty, while the variation of the Debye temperature shows a linear decrease with gold concentration. For iron-based alloys, out of the eleven solutes, six decrease the γ values linearly with solute concentration, c. Their values of (1⁄γ)Δγ⁄Δc are: Fe(Ti), −1.0; Fe(V), −2.2; Fe(Cr), −2.0; Fe(Co), −0.6; Fe(Mo), −0.8; and Fe(W), −2.4. Four solutes increase the γ-values nonlinearly with respect to the solute concentration. The average values of (1⁄γ)Δγ⁄Δc near c=0 are: Fe(Al), +1.2; Fe(Si), +0.6; Fe(Mn), +2.0 and Fe(Ni), +2.6. These data are utilized to discuss the applicability of the rigid band model as well as to correlate the changes with those of magnetic properties.
