Single crystals are materials in which the atomic order extends uninterrupted over the entirety of the specimen

The vast majority of crystalline solids are polycrystalline

The vast majority of crystalline solids are single crystals

Single crystals are extremely rare and they only exist in nature

Grain boundaries are beneficial in single crystals

Polycrystalline materials are composed of many small crystals or grains having different crystallographic orientations

A grain boundary is the boundary region separating two grains, wherein there is some atomic mismatch