Hirokatsu Aoki

Development of an electrostatic levitator for neutron diffraction structure analysis

An electrostatic levitation (ESL) furnace was designed for the neutron diffraction study of condensed matter. This apparatus is composed of an electrostatic levitator, a neutron inlet path with Cd slit, a 160 degree window for the scattered neutrons, a CO2 laser for sample heating, and an optical pyrometer for temperature measurements. A preliminary neutron diffraction experiment with this ESL was performed for polycrystalline alumina. The sample position could be controlled with an accuracy of ±0.1 mm. The observed Bragg peaks were in complete agreement with those derived from the lattice data of alumina obtained from the literature value. This indicates that this facility is attractive for the structural study of condensed matter without containers.

Structure of Liquid Ge at High Temperatures

Neutron diffraction measurements have been performed for liquid germanium over a wide temperature range from 1000°C to 1550°C. The structure factor of liquid germanium just above the melting point has a pronounced shoulder in the high momentum transfer region of the first peak, as also by our data confirmed. With increasing temperature, the position of the first peak moves slightly to a high value of Q and the shoulder becomes inconspicuous.

Self-diffusion under microgravity and structure of group IVB liquids

Abstract The self-diffusion coefficient, DS in liquid Sn was measured by a long capillary method in the microgravity environment of the space shuttle, and the validity of a microgravity effect was confirmed for the measurements of diffusion in melts with high melting temperatures. The data of this DS under microgravity were well reproduced by calculations, particularly in the case closely related to liquid structures. A systematic microgravity experiment is required to obtain further insight and to develop a model for diffusion in group IVB liquids.