Branching and twinning in α-cristobalite dendrites: an electron backscatter diffraction study

In this paper, the electron backscatter diffraction (EBSD) technique is used to determine the orientations of α-cristobalite dendrites. The two branches of the cross-shaped α-cristobalite dendrite extend along the crystallographic directions [100] and [010], but no branches develop along 〈001〉. A new kind of twinning relationship is found between two α-cristobalite dendrites. The twin axes are [110], [111] and [1], and the twin planes are (111) and (1). It is shown that crystallographic symmetry controls the dendrite morphology and dendrite aggregation.