Ion beam amorphization of muscovite mica
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Ion beam amorphization of muscovite mica C. Templier, F. Desage, and J. C. Desoyer Laboratoire de M´etallurgie Physique, 40 Av. Recteur Pineau 86022 Poitiers, Cedex, France
G. Hishmeh Midwest Research Technologies Inc., 14540 Greenfield Avenue, Brookfield, Wisconsin 53005
L. Cartz College of Engineering, Marquette University, Milwaukee, Wisconsin 53233
S. E. Donnelly and V. Vishnyakov Joule Laboratory, Science Research Institute, University of Salford M5 4WT, United Kingdom
R. C. Birtcher Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (Received 13 November 1995; accepted 6 February 1996)
The microstructure of a muscovite mica exposed to a rare gas ion beam has been studied by transmission electron microscopy. The investigation of damage without implantation was carried out using argon and helium ions of sufficient energy to traverse the 100 –150 nm mica specimens. For 340 keV Ar11 irradiation, amorphization of mica occurred at a fluence as low as 3.5 3 1014 ions ? cm22 , which corresponds to 0.29 dpa. Muscovite can be amorphized using 80 keV helium ions, but this requires a much higher fluence and damage production of 4.6 3 1016 ions ? cm22 and 0.60 dpa, respectively. Since helium irradiation results principally in ionization energy loss, it indicates that amorphization of muscovite results mainly from nuclear interactions. Complete amorphization of muscovite mica is found to take place for all ions at approximately the same amount of nuclear energy transfer to energetic primary knock-on atoms, assuming a recoil energy greater than 500 eV. This suggests that amorphization occurs directly in dense displacement cascades. A significant amount of helium, 100 ppm, can be implanted into muscovite mica without destroying the crystal structure.
I. INTRODUCTION
Phlogopite micas exhibit anomalous high thermal expansions perpendicular to the basal plane varying from below 1% up to 300% at 600 ±C, depending on their excess, nonstructural water content.1 This thermal expansion arises from the liquid-vapor transition of water bubbles located between the relatively flexible silicate layers. The attempt to develop thermal sensors using this effect has provided the motivation for rare gas implantation in mica. A less pronounced but similar thermal dilatation in a muscovite mica implanted with helium ions was believed to result from the expansion of He bubbles located between the silicate layers.2,3 This explanation is not valid if the mica becomes amorphous during the helium implantation since amorphous mica is expected to lose the flexible silicate layers. Heavier rare gases such as xenon and krypton implanted into muscovite mica permitted the unambiguous identification of the rare gas atoms in bubbles since their solidification occurs at low temperatures.4 Rare gases implanted at room temperature into metals precipitate in the form of solid bubbles, a few J. Mater. Res., Vol. 11, No. 7, Jul 1996
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