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NUCLEAR-MAGNETIC-RESONANCE LINE-SHAPE OF LA-139 IN NONSTOICHIOMETRIC LANTHANUM HYDRIDES AT LOW-TEMPERATURES
Tekijät: ZOGAL OJ, JUSZCZAK C, VUORIMAKI AH, YLINEN EE, PUNKKINEN M, DRULIS H
Kustantaja: ELSEVIER SCIENCE SA LAUSANNE
Julkaisuvuosi: 1993
Lehti:: Journal of Alloys and Compounds
Tietokannassa oleva lehden nimi: JOURNAL OF ALLOYS AND COMPOUNDS
Lehden akronyymi: J ALLOY COMPD
Vuosikerta: 191
Numero: 2
Aloitussivu: 207
Lopetussivu: 212
Sivujen määrä: 6
ISSN: 0925-8388
DOI: https://doi.org/10.1016/0925-8388(93)90066-V
Tiivistelmä
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.
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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