microstrain

Noun

 * 1)  A strain expressed in terms of parts per million
 * 2)  The root mean square of the variations in the lattice parameters across the individual crystallites, usually across microscopic distances, <ϵ2>1/2. By definition, it cannot be negative. In contrast, macrostrain refers to the overall change in the lattice parameters caused by a composition change or temperature change or pressure change.