B-O chemical bond length as a criterion for searching new acentric borate crystals

The relation “composition - structure - NLO property” is observed for a set of >200 acentric borate crystals. The distribution of the crystals over point groups is very inhomogeneous with domination of C 2v point group crystals. Acentric borates are distributed on the plane of the shortest chemical bond lengths metal-oxygen over an area, covered by a rosette of three partly crossing ellipses. The dependence of nonlinear optical susceptibility χ (2) on the shortest boron-oxygen bond length L(B-O) in borates has two maximums at L(B-O) = 136 and 148 pm.