Structural variations accompanied by thermal expansion of diaspore

Abstract

Single crystal X-ray diffraction experiments for diaspore have been worked in the temperature range from 22 to 425 ºC, in order to understand detailed mechanism of thermal expansion. Temperature variations of the cell parameters indicate that thermal expansion of the a-axis is higher than that of the b-axis or the c-axis. The results of the structure refinement suggest such anisotropic behavioris due to thermal expansion of the empty cavities in the structure of diaspore.