Hydrogen-isotope motion in scandium studied by ultrasonic measurements

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.893· OSTI ID:6490484

Leisure, R G ^[1]; Schwarz, R B; Migliori, A ^[2]; Torgeson, D R ^[3]; Svare, I ^[4]

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1. Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)
2. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
3. Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States)
4. Department of Physics, University of Trondheim, NTH, N-7034 Trondheim (Norway)

Resonant ultrasound spectroscopy has been used to investigate ultrasonic attenuation in single crystals of Sc, ScH[sub 0.25], and ScD[sub 0.18] over the temperature range of 10--300 K for frequencies near 1 MHz. Ultrasonic-attenuation peaks were observed in the samples containing H or D with the maximum attenuation occurring near 25 K for ScH[sub 0.25] and near 50 K for ScD[sub 0.18]. The general features of the data suggest that the motion reflected in the ultrasonic attenuation is closely related to the low-temperature motion seen in nulcear-magnetic-resonance spin-lattice-relaxation measurements. The ultrasonic results were fit with a two-level-system (TLS) model involving tunneling between highly asymmetric sites. The relaxation of the TLS was found to consist of two parts: a weakly temperature-dependent part, probably due to coupling to electrons; and a much more strongly temperature-dependent part, attributed to multiple-phonon processes. The strongly temperature-dependent part was almost two orders of magnitude faster in ScH[sub 0.25] than in ScD[sub 0.18], in accordance with the idea that tunneling is involved in the motion. Surprisingly, the weakly temperature-dependent part was found to be about the same for the two isotopes. The asymmetries primarily responsible for coupling the TLS to the ultrasound are attributed to interactions between hydrogen ions that lie on adjacent [ital c] axes. The results are consistent with an isotope-independent strength for the coupling of the TLS to the ultrasound.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6490484
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 48:2; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DEUTERIUM
DIFFUSION
HYDROGEN
SCANDIUM
ATOM TRANSPORT
ATTENUATION
FREQUENCY DEPENDENCE
ISOTOPE EFFECTS
MHZ RANGE 01-100
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TUNNEL EFFECT
ULTRASONIC WAVES
ELEMENTS
FREQUENCY RANGE
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
METALS
MHZ RANGE
NEUTRAL-PARTICLE TRANSPORT
NONMETALS
NUCLEI
ODD-ODD NUCLEI
RADIATION TRANSPORT
SOUND WAVES
STABLE ISOTOPES
TEMPERATURE RANGE
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation