Free Access
Microsc. Microanal. Microstruct.
Volume 7, Number 3, June 1996
Page(s) 153 - 160
Microsc. Microanal. Microstruct. 7, 153-160 (1996)
DOI: 10.1051/mmm:1996111

Cross-Sectional Observations of Polymorphic FeGe Interphases

Kazutomo Suenaga1, Alain Thorel1, Philippe Houdy2 et Christian Colliex3

1  Centre des Matériaux Pierre-Marie Fourt, École Nationale Supérieure des Mines de Paris, BP 87, 91003 Évry, France
2  Laboratoire Multicouches Nanométriques, Université d'Évry, Bd des Coquibus, 91025 Évry, France
3  Laboratoire de Physique des Solides, URA CNRS 002, Bâtiment 510, Université Paris-Sud, 91405 Orsay Cedex, France

Cross-sectional microscopy is performed on ${\rm Fe}_x{\rm
Ge}_{1-x}$ multilayers with steep concentration gradients. A profile in high angle annular dark field imaging mode demonstrates the presence of an intermetallic phase appearing brighter in Z-contrast, which is proved to be $\alpha\rm\mbox{-}FeGe$ alloy by means of associated quantitative contrast calculations. Fourier analysis of lattice fringes observed by transmission electron microscopy reveals the previously found non-magnetic interphase as $\rm\eta\mbox{-}Fe_6Ge_5$. These results are discussed here with reference to recent work using Mössbauer spectroscopy, kinetic ellipsometry, and Fe L-edge EELS analysis. An attempt is then made to correlate them with phase separation models involving nanometric inhomogeneities in FeGe alloys.

6155H - Crystal structure of specific alloys.
6855 - Thin film growth, structure, and epitaxy.

Key words
crystal structure -- germanium alloys -- iron alloys -- polymorphism -- transmission electron microscopy -- polymorphic FeGe interphases -- cross sectional microscopy -- steep concentration gradients -- high angle annular dark field imaging mode -- Fourier analysis -- lattice fringes -- transmission electron microscopy -- Mossbauer spectroscopy -- kinetic ellipsometry -- Fe L edge EELS analysis -- FeGe

© EDP Sciences 1996