الفهرس 
The mossbauer effectOnly 14 pages are availabe for public view
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Abstract
Mijssbauer spectroscopy with the 14.4 keV resonance of 57Fe has been used to study the nickel-hydrogen system. The magnetic properties of Fe impurities were studied in a magnet cryostat, with the source and absorber immersed into the liquid helium. Measurements were made on two different samples. One was a 14 pm thick foil loaded under high hydrogen pressure to a hydrogen-to-metal ratio of x= 1.02, and consisting of the pure nonmagnetic P-Ni hydride phase. After the measurements in external magnetic fields up to 6 T the sample warmed again to room temperature for a few seconds and immediately again quenched into liquid nitrogen. After this treatment, another set of measurements in different external fields was performed. The second sample was a 9.5 pm thick foil that had been hydrogenated electrolytically. This sample still contained 15 % of the magnetic virtually hydrogen-free phase. Its overall hydrogen content was x= 0.87, the corresponding average hydrogen content of the hydride fraction thus was x=1.02. By fitting the zero-field spectra, we obtain the isomer shift parameters AS,= (0.03 f 0.01) mm/sec and AS= (0.09 f 0.01) mm/sec, where AS, is the shift of iron species without nearest hydrogen neighbours with respect to iron in hydrogen-free nickel, and AS the additional shift caused by each additional nearest hydrogen neighbour surrounding the iron. As well as the probabilities Pi with which Fe solutes with i (the nearest hydrogen neighbours) occur for each one of the studied samples. Both the atomic magnetic moment p(i) and the saturation hyperfine field Bsat(i) of Fe species with i nearest neighbours have been found to decrease with increasing isle saturation hyperfine fields are Bsat(0)= (24 f 1) T for both the samples loaded electrolytically and under high pressure, Bsat(4)= (20 f 1) T in the pressure loaded sample and Bsat(6)= (17 f 2) T in the electrolytically loaded sample. The magnetic moments decrease with i from p(O)= (4.7 f 0.5) p~ to p(6)= (2.2 f 1.0) p~. The hydrogen distribution near the Fe probes is characterized by a repulsive interaction between the iron impurities and the interstitials. Non-equilibrium distributions can be frozen in by rapid cooling. The relaxation of the hydrogen distribution near the iron probes has been studied at temperatures of 150, 145, 140, and 130 K. This relaxation results in changes of the line widths and of the centre shifts, the latter being between 0.222 and 0.153 mm/sec.