Synthesis, conductivity behaviour and second-order nonlinear optics of partially substituted double KDP containing As~(5+) and Na~+

摘要

A new solid solution K_(0.95)Na_(0.05)H_2(PO _4)_(0.5)(AsO_4)_(0.5) abbreviated (KNDAP) has been prepared by slow evaporation of an aqueous solution at room temperature. Its crystal structure which was solved by the direct method from single crystal X-ray diffraction data can give birth to two kinds of disorder. The first one is statistical or dynamical in the shortest OH~?O hydrogen bond that can facilitate the migration of proton. As for the second kind, it is related to the effect of the substitution of Na~+ and As~(5+) in the same site occupancy as that of the K~+ and P~(5+), respectively. This disorder could promote hard defects in the structure, which can enhance the physical properties, especially, the conductivity.