Crystal structure of aluminum melted in high vacuum

To make a highly perfect aluminum crystal, high purity aluminum was melted in high vacuum of 2 x 10(-7) Pa for 2 h using a cold-crucible induction fur nace. The surface of as-melted ingot had a metallic luster and heavy oxidiz ation was not observed on the surface. In the ingot, a large cylindrical-si ngle crystal with a diameter of 60 mm and a length of 40 mm grew and disloc ation density in the crystal was about 10(7) m(-2). Purity of the melted al uminum was estimated to be near 99.9999% from the residual resistivity rati o. A large amount of highly perfect aluminum crystal with ultra-high purity was produced by only melting of melting once, under an ultra-high vacuum.