RARE-GAS BUBBLES IN MUSCOVITE MICA IMPLANTED WITH XENON AND KRYPTON

Xenon and krypton have been implanted into muscovite mica at room temp erature and at liquid nitrogen temperature. The behavior of the implan ted Xe and Kr was followed by low-temperature transmission electron mi croscopy and energy dispersive x-ray analysis. An electron diffraction pattern of diffuse bands is observed at room temperature due to the p resence of fluid rare gas and to noncrystalline mica. Visible cavities with diameters 10-300 nm formed in the Xe-implanted mica. Visible cav ities in room-temperature Kr-implanted mica ranged from 5-50 nm in dia meter. The gas pressures at room temperature in the cavities are estim ated, assuming all of the implanted gas precipitated in cavities to be approximately 10 MPa for Xe and approximately 20 MPa for Kr. These pr essures are considerably lower than found for rare gases implanted in metals and ceramics, but sufficient to liquefy the rare gases at room temperature. The Xe and Kr were observed by dark-field microscopy to f orm fcc crystalline solids within the cavities at temperatures below t heir triple points, with lattice parameters of a(Xe) = 0.630 +/- 0.001 5 nm and a(Kr) = 0.565 +/- 0.005 nm. The solid Xe within bubbles was u nstable under the electron beam of the transmission electron microscop e at temperatures above 80 K, while the solid Kr within bubbles was un stable at temperatures as low as 35 K. The crystalline mica matrix und ergoes a transformation from a crystalline structure to an amorphous s tructure as a result of implantation.