Research Article
Belokoneva EL, Stefanovich SY,
Abstract
Silicates, phosphates, borates and complex compounds as borosilicates and borophosphates have been synthesized under hydrothermal conditions similar to common in nature, and structurally investigated in the past decade in search of optical nonlinear crystals. Representatives with voids or channels of effective cross sections up to 10 Å are selected and analyzed from the point of view crystal chemistry and possible applications. It is noticed that crystals with framework or layered structures equally accumulate in their voids large ions, or groups of ions, or water molecules from the water solution during the crystallization, and frequently exhibit zeolite properties. Frameworks built on the base of silicate, phosphate or boron tetrahedral demonstrate topological similarity. In a number of crystals the zeolite properties appear in combination with optical non-linearity that is being the bottom of their attraction for integral optics. In non-centro symmetric crystals origin of high optical non-linearity is connected with the highly polarizable electron density of heavy atoms in the voids and channels of the structures. Significant rules are withdrawn from the results of hydrothermal synthesis of crystalline micro porous materials.