The OCN− vibrational spectrum and the phase transitions in KCNxKCl1−x single crystals

Abstract

AbstractThe OCN− bending mode and Fermi resonances are studied in pure KCN and in mixed KCNxKCl1−x crystals. The two phase transitions in these salts are followed as a function of the Cl− concentration. By the application of uniaxial stress in the mixed crystals almost single domain regions are formed that allow to verify that the CN− and OCN− alignment in the orthorhombic phase is along the (110) direction. These single domain regions keep their alignment without applied stress by temperatures below the cubic orthorhombic phase transition. No change in dichroism is found in cooling the crystal to very low temperatures.