Isotope Fluctuation in Indium-Lead Alloy Induced by Solid Centrifugation

The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 0.81 x 10(6)G for 100 hours at 150 degrees C (solid state) in our previous study. The isotope fluctuation on this sample was measured using secondary ion mass spectrometer (SIMS). The In-115/In-113 isotope ratio changed with positive gradient in the direction of centrifugal force approximately 1.2%. The isotope ratio fluctuation of centrifuged sample was 4 times larger than that of starting sample (<0.3%). This showed that the isotope fractionation effect was induced by solid centrifugation in this alloy, although achieved concentration gradients were small.