Ga-69 nuclear magnetic resonance spectra, line shifts (K-69) and nuclear spin-lattice relaxation rate T-69(1)-1 have been measured in the 20 years aged Pu0.95Ga0.05 and in fresh prepared Pu0.92Ga0.08 alloys. stabilized delta-phase, at magnetic field of 9.4 T in the temperature range (10-500) K. The line shift and T-69(1)-1 are determined correspondingly by the static and fluctuating-in-time parts of the local magnetic field that originates in transferred hyperfine coupling the Ga nuclear spin with the nearest f-electron environment of more magnetic Pu.Temperature behavior of the resonance properties is found the same in fresh Pu0.92Ga0.08 and aged Pu0.95Ga0.05 alloy. The NMR results are in favor that delta-phase of Pu1-xGax alloys represents at T > 200 K the Kondo lattice, in which the localized electronic spins fluctuate independently from each other without any macroscopic coherence. The coherent state like in heavy-fermion liquids emerges in Pu0.95Ga0.05 below T-center dot = 200 K. A little bit higher estimate of crossover temperature T-center dot = 250 K was founded for Pu0.92Ga0.08. (C) 2008 Elsevier B.V. All rights reserved.

69Ga nuclear magnetic resonance (NMR) experiments have been carried out on the Pu0.995Ga0.005 alloy at temperatures between 20 and 420K at magnetic field of 9.4T to study the local charge symmetry and magnetic behavior of the Pu atoms surrounding solute Ga. In accordance with optical metallography and X-ray diffraction studies the investigated plates of alloy (20mm×3mm×0.2mm) represent at room temperature the single α-phase material without any detectable macroscopic segregation of other phases (the corresponding volume fraction <0.03). It was revealed that the magnetic shift of the 69Ga NMR central line and the electric quadrupole broadening of the Ga NMR spectrum trace temperature dependence of the NMR parameters is observed for the δ-phase plutonium alloy Pu0.95Ga0.05. On the basis of 69Ga NMR and X-ray data obtained, it is suggested that specific microscopic areas with a size less than 100nm exist in the α-phase plutonium alloys Pu0.995Ga0.005. The local charge and magnetic environment of the solute Ga in these microscopic areas are similar to the observed in the stabilized δ-Pu alloy.

69Ga nuclear magnetic resonance (NMR) line shift (69K) and nuclear spin–lattice relaxation rate (69T1−1) are measured for Pu0.95Ga0.05 alloy, stabilized in δ-phase, in the temperature range 10 and 650K at magnetic field of 9.4T. The shift and 69T1−1 are determined correspondingly by the static and fluctuating-in-time parts of the local magnetic fields arisen at Ga due to transferred hyperfine coupling with the nearest f electron environment of more magnetic Pu. At T>200K, the temperature dependent part of the shift 69K(T) scales macroscopic magnetic susceptibility χ(T), following the Curie–Weiss law, and the product (69T1T) increases with temperature proportionally (T+255)1.5(1). Both of the NMR observations are typical of the incoherent spin fluctuation regime of f electrons in nonmagnetic 3D Kondo lattice. An estimate of the effective magnetic moment μeff,5f(ge=2)=0.15(5)μB per Pu atom points out a strong suppression of the spin magnetism in the alloy.