Isochronal annealing studies in Pu and Pu alloys using magnetic susceptibility

• Published in: Journal of alloys and compounds 2007-10, Vol.444, p.168-173
• Main Authors: McCall, S.K., Fluss, M.J., Chung, B.W., McElfresh, M.W., Chapline, G.F., Jackson, D.D., Haire, R.G.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic measurements; Magnetic properties and materials; Metals and alloys; Physics; Studies of specific magnetic materials; Vacancy information
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2006.12.090

The isochronal annealing of the low temperature accumulated damage from the radioactive decay of plutonium in α-Pu, δ-Pu 1− x Ga x ( x = 0.043) and δ-Pu 1− x Am x ( x = 0.224) was characterized using magnetic susceptibility. In each specimen, thermal annealing, as tracked by magnetic susceptibility, only commenced when T > 33 K and the magnetic susceptibility changes due to defects were fully annealed at T ∼ 300 K. The α-Pu magnetic susceptibility isochronal annealing data is similar to earlier measurements of resistivity characterized isochronal annealing. However, the δ-Pu 1− x Ga x ( x = 0.043) magnetic susceptibility isochronal annealing data, when compared with similar resistivity data, indicates that for this alloy magnetic susceptibility studies are more sensitive to vacancies than to the interstitials accumulated at low temperatures. The Pu 1− x Am x ( x = 0.224) alloy shows a remarkable change in properties, over a limited temperature range beginning where interstitial defects are first mobile, and characterized by an induced effective moment of order 1.1 μ B/Pu. This transient behavior may be evidence for a disorder driven low temperature phase transition, perhaps indicative of a compositional and structural proximity to a state possessing significant magnetic moments.