The non-additivity and curvature corrections in the variance method of X-ray line-broadening analysis

A previous paper by Edwards & Toman on the subject of the variance non-additivity and curvature corrections is revised and extended. The formula for the curvature correction is given in a form which facilitates evaluation for cases of crystallite size broadening by crystallites of known shape; the formula involves the shape parameter M which is evaluated for the shapes of a sphere, a rectangular parallelepiped, a tetrahedron and an octahedron.