Elastic properties of Pd-hydrogen, Pd-deuterium, and Pd-tritium single crystals

Journal Article · Tue Feb 01 04:00:00 EST 2005 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2004.10.009· OSTI ID:20637134

Schwarz, R B ^[1]; Bach, H T ^[1]; Harms, U ^[1]; Tuggle, D ^[1]

---

1. Los Alamos National Laboratory, MSTs, Division and ESA Mail Stop G755, Los Alamos, NM 87545 (United States)

We used a resonant-ultrasound-spectroscopy technique to measure the three independent elastic constants of PdH{sub x}, PdD{sub x}, and PdT{sub x} single crystals at 300 K. For 0.1x0.62 our PdH{sub x} crystals are two-phase mixtures of coherent {alpha} and {beta} hydride phases. For increasing x in this range, C{sub 44} decreases monotonically whereas C'=12(C11-C12) has a concave parabolic dependence. This difference is because C' is softened by an anelastic relaxation resulting from acoustic-stress-induced changes in the shape of the coherent lenticular-shape precipitates ({beta}-hydride precipitates in {alpha}-hydride matrix and {alpha}-hydride precipitates in {beta}-hydride matrix). In the {beta}-phase C' and C{sub 44} decrease with increasing hydrogen (or deuterium or tritium) content. Furthermore, C' exhibits a strong isotope effect whereas C{sub 44} does not. This effect is attributed to differences in the excitation of optical phonons in Pd-H, Pd-D and Pd-T.

• OSTI ID: 20637134
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 3 Vol. 53; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DEUTERIDES
ELASTICITY
ISOTOPE EFFECTS
MONOCRYSTALS
PALLADIUM COMPOUNDS
PALLADIUM HYDRIDES
PHONONS
SPECTROSCOPY
STRESSES
TRITIDES
ULTRASONIC WAVES