Preparation and structural properties of nonlinear optical borates K[sub]2(1-x)Rb[sub]2xAl[sub]2B[sub]2O[sub]7, 0 < x < 0.75

The structures of K[sub]2(1-x)Rb[sub]2xAl[sub]2B[sub]2O[sub]7, x = 0.25, 0.5, 0.75, have been determined in space group P321 through Rietveld analysis of X-ray powder diffraction data. The solubility limit in K[sub]2(1-x)Rb[sub]2xAl[sub]2B[sub]2O[sub]7 crystals has been estimated as x similar to 0.83-0.9. Nonlinear optical properties of KRbAl[sub]2B[sub]2O[sub]7 have been verified by powder Kurtz-Perry method. Mechanisms of structural parameter variation in K[sub]2Al[sub]2B[sub]2O[sub]7 crystal family have been discussed.