By using in situ transmission electron microscopy, it was found that there existed a universal symmetry property among point defects. This was that the symmetry of short-range order in point defects mirrored the crystal symmetry when in equilibrium. It was further shown that this symmetry-conforming property could lead to various interesting effects. These included a so-called aging-induced microstructure memory and an associated time-dependent 2-way shape memory.

Universal Symmetry Property of Point Defects in Crystals. X.Ren, K.Otsuka: Physical Review Letters, 2000, 85[5], 1016-9