A1 Refereed original research article in a scientific journal
Low-temperature H-1 nuclear magnetic resonance study of crystal and electronic structures of the nearly stoichiometric yttrium dihydride
Authors: Zogal OJ, Vuorimaki AH, Ylinen EE
Publisher: TAYLOR & FRANCIS LTD
Publication year: 2000
Journal:: Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
Journal name in source: PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS AND MECHANICAL PROPERTIES
Journal acronym: PHILOS MAG A
Volume: 80
Issue: 11
First page : 2549
Last page: 2558
Number of pages: 10
ISSN: 0141-8610
DOI: https://doi.org/10.1080/01418610008216491
Abstract
Proton nuclear magnetic resonance absorption spectra and spin-lattice relaxation rates in yttrium dihydride have been measured in the temperature range from 4.2 to 310 K at 36.0 MHz. The second moment of the resonance line corresponds to the rigid-lattice regime for YH1.99 and its value agrees with the anticipated CaF2 type of structure. The main contribution to the spin-lattice relaxation rate R-1 arises from conduction electrons and is characterized by R-1e = 2.77 x 10(-3) s(-1) K-1 x T. Evidence of proton self-diffusion was seen in the linewidth and in R-1 for YH1.99+0.1 The onset temperature, about 250 K, of the self-diffusion, is close to the metal-semiconductor transition reported earlier for that hydride. Below that temperature the linewidth becomes temperature independent and the second moment of the line is explained in terms of different structure models. The fit to the temperature dependence of R-1 in the temperature range 70-310 K gives R-1e = 2.1 x 10(-3) s(-1) K-1 x T. The relaxation becomes almost temperature independent below 50 K. Various mechanisms for this behaviour are discussed. In addition, the R-1 data for the sample prepared with yttrium of 99.9% purity are presented. In contrast with the previous case, where pure yttrium from the Ames Laboratory was used, R-1 has a large contribution of spin diffusion to the paramagnetic Gd3+ ions.
Proton nuclear magnetic resonance absorption spectra and spin-lattice relaxation rates in yttrium dihydride have been measured in the temperature range from 4.2 to 310 K at 36.0 MHz. The second moment of the resonance line corresponds to the rigid-lattice regime for YH1.99 and its value agrees with the anticipated CaF2 type of structure. The main contribution to the spin-lattice relaxation rate R-1 arises from conduction electrons and is characterized by R-1e = 2.77 x 10(-3) s(-1) K-1 x T. Evidence of proton self-diffusion was seen in the linewidth and in R-1 for YH1.99+0.1 The onset temperature, about 250 K, of the self-diffusion, is close to the metal-semiconductor transition reported earlier for that hydride. Below that temperature the linewidth becomes temperature independent and the second moment of the line is explained in terms of different structure models. The fit to the temperature dependence of R-1 in the temperature range 70-310 K gives R-1e = 2.1 x 10(-3) s(-1) K-1 x T. The relaxation becomes almost temperature independent below 50 K. Various mechanisms for this behaviour are discussed. In addition, the R-1 data for the sample prepared with yttrium of 99.9% purity are presented. In contrast with the previous case, where pure yttrium from the Ames Laboratory was used, R-1 has a large contribution of spin diffusion to the paramagnetic Gd3+ ions.
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