PHASE-TRANSITION INDUCED BY BALL MILLING IN GERMANIUM

The paper reports on the crystal-to-amorphous phase transition induced by ball milling in a pure element: a germanium powder. Scanning electron micrographs show some spherical particles with smooth shapes. The container contamination, which was determined by chemical energy dispersive X-ray/scanning electron microscopy microanalyses, was found to be less than or equal to 0.5 at.% of iron (no significant chromium contamination could be detected). The analyses of the X-ray patterns reveal the coexistence of germanium microcrystallites and an amorphous phase. Some particles of about 100-200 nm in diameter exhibit a pure amorphous structure (bright field images and selected area diffraction patterns). The influence of the ball milling conditions on the dynamic end-product between the crystalline and the amorphous phases has been studied.