Synthesis, conductivity behaviour and second-order nonlinear optics of partially substituted double KDP containing As5+ and Na+

Abstract 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 OH … 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.