Determination of vibrational properties of Pu and Ga in a Pu-3.6at.%Ga alloy using neutron resonance Doppler spectroscopy
Abstract
We have determined some of the phonon spectral parameters for Pu and Ga in the "stabilized" δ-phase (fcc) of the Pu-3.6at.%Ga alloy by measuring the Doppler broadening of neutron resonances as a function of temperature. We find the mean phonon energy (first moment of the phonon spectrum) of Pu to be <hν> =3D 8.23=B10.12 meV and the second moment to = be <(h ν)^2> =3D 7.3=B10.4 x 10-5 eV^2. These moments and the value of the (-1)^st moment determined from Debye-Waller factors from neutron powder diffraction are consistent with a Debye model with a Debye temperature of ≈127 K. For Ga in the Pu-Ga alloy, <h ν> =3D 16.4=B11.0 meV, which lies roughly halfway between its value in pure α-Ga, <hν> =3D 17.4=B10.4 meV, and the m^1/2 weighted value expected on the basis of the value for Pu (15.3 meV); however, the measured value for the alloy cannot be distinguished from either of the latter values within the experimental error. These results show that Pu-3.6At.%Ga behaves very much like a Debye solid at ambient pressures and low temperature, and that the Ga impurity experiences pretty much the same force field that the Pu it replaces experiences.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 1998
- Bibcode:
- 1998APS..MAR.G1503L