NEW NONLINEAR OPTICAL MATERIALS - METAL OXIDES WITH NONBONDED ELECTRONS

Molecules or ions of the form BOx-n lack a center of symmetry whenever the B atom has a nonbonded pair of electrons. The problem of generating an acentric crystal can be approached by using these acentric oxygen polyhedrons as building blocks. A very high incidence of acentricity is found in compounds based on distorted BO3-n octahedra, such as XeO3, AIO3 (A=H, Li, Na, K, Rb, Cs, NH4, and Tl), and MTeO3 (M=Ca, Sr, Ba, Zn, Cd, Hg, Pb, Ni). Since these materials also have large indices of refraction, the concept of acentricity via nonbonded electrons provides a new and important guideline in the search for nonlinear optical materials. © 1969 The American Institute of Physics.