NUCLEAR-MAGNETIC-RESONANCE LINE-SHAPE OF LA-139 IN NONSTOICHIOMETRIC LANTHANUM HYDRIDES AT LOW-TEMPERATURES



: ZOGAL OJ, JUSZCZAK C, VUORIMAKI AH, YLINEN EE, PUNKKINEN M, DRULIS H

Publisher: ELSEVIER SCIENCE SA LAUSANNE

: 1993

Journal of Alloys and Compounds

JOURNAL OF ALLOYS AND COMPOUNDS

: J ALLOY COMPD

: 191

: 2

: 207

: 212

: 6

: 0925-8388

DOI: https://doi.org/10.1016/0925-8388(93)90066-V


The La-139 nuclear magnetic resonance of lanthanum hydrides in LaH2+x (x = 0.32, 0.38, 0.40, 0.74) was measured over the temperature range 2.3 to 303 K. A single, temperature-dependent line width was found in LaH2.74 above 250 K, whereas a complex spectrum was observed at lower temperatures. The low temperature line shape can be described as the superposition of two resonances with the same intensity but different electric field gradients and Knight shift tensors. They were correlated with two lanthanum sites in the LaH2.75 superlattice proposed on the basis of neutron diffraction and specific heat measurements. For the LaH2.32-LaH2.40 samples, the spectrum can also be decomposed into two resonances. However, in this case, one line can be attributed to the LaH2.5 superlattice and the origin of the second line is briefly discussed.



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