ELASTIC AND ANELASTIC BEHAVIOR OF SEVERAL DELTA-STABILIZED PLUTONIUM ALLOYS AT LOW TEMPERATURES

The temperature dependence of the elastic moduli, adiabatic compressibilities, Debye temperatures and ultrasonic wave attenuations of several delta-stabilized plutonium alloys (with aluminum and cerium) has been investigated in the range 4·2-300°K. The behavior of the elasticity and anelasticity of these alloys, similar to alpha plutonium, was found to be inconsistent with the antiferromagnetic model. The observed anomalies in the longitudinal wave attenuation in these alloys, support the possible existence of a cooperative electron transition in the vicinity of 65°K. It is shown that the cooperative effect, as manifested by the anomalies in the longitudinal wave attenuation, is due to the plutonium itself. Alloying additions serve as diluents and weaken the interaction which leads to the cooperative phenomenon. The behavior of both longitudinal and transverse wave attenuations at temperatures above 130°K indicates the possibility of operation of a thermally-activated interband electron transfer. © 1969.