Growth and characterization of dichloro tetrakis thiourea nickel single crystals

Thiourea has a large dipole moment and has an ability to form extensive network of hydrogen bonds. In the course of our studies on new semiorganic NLO materials, thiourea is selected to combine with nickel chloride. Single crystals of tetrakis thiourea nickel chloride are grown using silica gel. Green transparent crystals of NTC (nickel thiourea chloride) of dimension 8x4x3 mm³ are grown in a period of 45 days. Single crystal XRD shows that the crystal belongs to body centered tetragonal symmetry class I4. The UV‐Vis‐NIR spectrum establishes the transmission range to be 300 nm to 2500 nm, with a sharp absorption peak at the red end of the visible region, which is due to the colour of the crystal. Photoconductivity and dielectric studies are also carried out. The mechanical strength of the crystal is estimated by Vickers hardness test. The crystal starts decomposing after about 200°C. Thus, we confirm from our present investigation that NTC is a suitable candidate for NLO applications. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)