Pressure action on binary alloys produces new
intermediate phases [1]. On pressure release, these
phases can transform to metastable states as crystalline
as well as amorphous. Alloy amorphization was observed
after pressure quenching in some alloy systems (Zn-Sb,
Cd-Sb, Al-Ge) [2].
Amorphous alloy Al30Ge70 was shown to crystallize
under pressure into simple hexagonal, sh, phase [3]. This
amorphous-to-crystal transformation is reversible and
has diffusionless character. Crystallization of amorphous
alloy into equilibrum phase mixture Al+Ge occurs under
heating (200 C, 17 hours) and this transformation is
characterized as diffusion kinetic process.
Semiconducting compounds CdSb ad ZnSb were shown
[4] to destruct under pressure forming high-pressure
phase of simple hexagonal structure (~60 at% Sb) and
separating out excess of Zn or Cd. On pressure release,
these alloys transformed into amorphous state.
Diffraction spectra of amorphous alloys have two
strong broaden peaks, similar to amorphous
semiconductors.
Amorphous states were observed in alloys about
electron concentration ~3.8 electron/atom. Applying
Nagel-Tauc criterion for amorphous state one can obtain
that the reciprocal vector for second peak is nearly 1/2
of Fermi sphere radius. These features provide the
consideration of amorphous alloys discussed as a kind of
"electronic" phases.
[1] E. G. Ponyatovskii and V. F. Degtyareva
High pressure research 1 (3), 163 (1989)
[2] V. F. Degtyareva, I. T. Belash, and E. G. Ponyatovskii,
Phys. Stat. Solidi (a) 124, 465 (1991)
[3] V. F. Degtyareva, F. Porsch, E. G. Ponyatovskii, and
W. B. Holzapfel, Phys. Rev. B 53 (13), 8337 (1996)
[4] V. F. Degtyareva, I. Bdikin, S. S. Khasanov,
Fiz.Tverd.Tela (St. Petersburg) 39 (9), 1509 (1997)
[Phys. Solid State 39 (9), 1341 (1997)]
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