Magnetic properties and crystal structure of β-Ta

Polycrystalline samples of β-Ta with Frank-Kasper σ-phase structure prepared by electrolysis are studied. The atomic parameters are determined by the Rietveld method. The magnetic susceptibility is measured in the temperature range 4.2 < T < 273 K and the dependence of the magnetization on the magnetic field strength is measured at 4.2 and 77 K. The analysis of interatomic distances and the results of magnetic measurements indicate that clusters with a localized excess charge exist in β-Ta. The data obtained in this study suggest structural changes in β-Ta at T < 77 K.