Growth actuated bending and twisting of single crystals

Crystals of a variety of substances including elements, minerals, simple salts, organic molecular crystals, and high polymers forgo long-range translational order by twisting and bending as they grow. These deviations have been observed in crystals ranging in size from nanometers to centimeters. How and why so many materials choose dramatic non-crystallographic distortions is analyzed, with an emphasis on crystal chemistries that give rise to stresses operating either on surfaces of crystallites or within the bulk. Twisted crystals: Crystals of many substances, including hippuric acid (see picture), will bend or twist as they grow under some conditions. These deviations are often activated by particular additives. How and why so many materials choose dramatic non-crystallographic distortions is analyzed for molecular crystals, high polymers, minerals, elements, and salts.