https://doi.org/10.1007/s100510050266
Lattice damage and Al-metal precipitation in 2.5 MeV-electron-irradiated AlH3
1
Institute of Low-Temperature and Structure Research, Polish Academy of
Sciences, 50-950 Wroclaw 2, Poland
2
Laboratoire des Solides Irradiés, CNRS-CEA, École
Polytechnique, 91128 Palaiseau, France
Corresponding authors: a zogal@int.pan.wroc.pl - b peter.vajda@polytechnique.fr
Received:
20
October
1997
Revised:
24
December
1997
Accepted:
30
January
1998
Published online: 15 April 1998
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 
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) 
. 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 
to 
, 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.
PACS: 61.72.Ji – Point defects (vacancies, interstitials, color centers, etc.) and defect clusters / 76.30.Mi – Color centers and other defects / 76.60.Cq – Chemical and Knight shifts
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998
