Large quantities of rhombohedra and elongated rhombohedra boron sub-oxide platelets with flat (001) surface were synthesized through conventional solid state reaction. Detailed structural investigations by selected area electron diffraction and high-resolution electron microscopy of these platelets were presented. Direct experimental observations were made of extensive lateral (001) microtwins in rhombohedra platelets, and these gave rise to the fractional diffraction spots. It was believed that the growth of these rhombohedra platelets was prompted by the twin-plane re-entrant edge mechanism. The transition from rhombohedra platelets to elongated rhombohedra platelets in morphology was probably the result of catalytic growth at the apices of the platelets. This proposed growth model could be representative of various platelets with low defects formation energy, especially in twinned crystals having a rhombohedra structure. Besides, the presence of extensive microtwins will yield interesting physical properties and probably resulted in the broadening of photoluminescence spectra from the rhombohedra and elongated rhombohedra platelets.

Twin-Plane Reentrant Edge Growth of Rhombohedra Boron Suboxide Platelets. Z.Yu, J.Jiang, J.Yuan, J.Zhu: Journal of Crystal Growth, 2010, 312[10], 1789-92