Abstract:
AlH3 powder was bombarded with energetic electrons at 20 K and at room temperature and investigated by EPR, NMR, X-ray diffractometry, and microwave dielectric-constant measurements. The EPR spectra of the irradiated powder and of a selected single crystal cuboid of \( \sim {10^{ - 1}}\) mm edge show a complex asymmetric line centered at g = 2.009, with a Curie-like temperature dependence, attributed to radiation-induced color centers and/or their agglomerates. At the same time, the grains, which have become shiny black after irradiation, exhibit an increase of both the real and the imaginary part of ε. 27Al-NMR spectra of the irradiated powder present a Knight-shifted line at 1600(50) ppm, close to the position of bulk metallic Al, and corresponding to a concentration of c(Al) \( \sim {10^{ - 1}}\). In addition, the main hydride line differs from that before irradiation, demonstrating an alteration of environmental symmetry. The irradiation induces also a change in shape and width of the 1H-NMR line, another indication of symmetry change in the lattice. Finally, a refined X-ray single-crystal structure analysis of the irradiated cuboid indicates a change of structure from trigonal R -3 c to R -3, with a loss of mirror symmetry for the two Al sites caused by the introduction of Al-defects in the vicinity of one of them.
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Received: 20 October 1997 / Revised: 24 December 1997 / Accepted: 30 January 1998
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Zogal, O., Vajda, P., Beuneu, F. et al. Lattice damage and Al-metal precipitation in 2.5 MeV-electron-irradiated AlH3 . Eur. Phys. J. B 2, 451–456 (1998). https://doi.org/10.1007/s100510050266
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DOI: https://doi.org/10.1007/s100510050266