Raman scattering investigation of the zinc cadmium tetrathiocyanate single crystals

The crystal growth, space group and Raman spectra of the zinc cadmium tetrathiocyanate (ZCTC) single crystal are introduced. The experiments show that the characteristic lattice vibrational modes of ZCTC crystal arises mainly from the internal vibrations of the SCN, ZnN4, and CdS4 groups. These modes are assigned as v1 (160 cm−1, a doubly degenerate CdS4 bending vibration), v2 (230 cm−1, a doubly degenerate ZnN4 bending vibration), v3 (449 cm−1, an NCS symmetrical bending vibration), v4 (474 cm−1, an NCS asymmetrical bending vibration), v5 (794 cm−1, a CS stretching vibration), and v6 (2179 cm−1, a CN stretching vibration), respectively. The three-dimensional network structure of ZCTC crystal is identified, and the high nonlinearity of the crystal is mainly attributed to the conjugated charge-transfer bridges(CdSCNZn) that connect all the distorted tetrahedron ZnN4 and CdS4 together.