Growth and properties of UV nonlinear optical crystal ZnCd(SCN)4

A second-order nonlinear optical coordination crystal, zinc cadmium thiocyanate, ZnCd(SCN)4 (ZCTC) was grown as a frequency doubler, emitting UV light. A large typical single crystal with dimensions up to 15 × 7 × 7 mm3 has been obtained by slow solvent-evaporation method for the first time. The infrared (IR) spectroscopy and X-ray powder diffraction (XRPD) of single crystals were performed at room temperature. The specific heat of the crystal has been measured to be 367.9 J/mol.K at 300 K. The thermal expansion coefficients, c- and a-oriented, have been measured to be −1.69 × 10−5 and 1.95 × 10−4 K−1, respectively. The second harmonic generation (SHG) efficiency of ZCTC crystal is 51.6 times as high as that of urea reference, and the measured transmittance spectra from 190 to 3200 nm showed that the UV transparency cutoff occurs at 290 nm and the transmission is 73.22% at 380 nm. UV laser light of wavelength 380 nm has been achieved by the frequency doubling of a 760 nm laser diode at room temperature.