Impact of copper doping on thermal, optical and electrical properties of strontium L(+) tartrate pentahydrate crystals

Abstract

Single crystals of intrinsic strontium L(+) tartrate (IST) and Cu2+ doped strontium L(+) tartrate (CuDST) are synthesized using single test tube gel diffusion technique. At ambient temperature, specific gravities of 1.050 and 1.055 and gel pH of 4.0 and 4.2 (with 0.5 M inner and upper reactants) are found to ensure optimized growth and quality of IST and CuDST crystals, respectively. These crystals show maximum sizes of 4.2 × 1.7 × 1.3 mm3 (for IST) and 5.1 × 0.9 × 0.8 mm3 (CuDST). Doping is observed to change the morphology of IST crystal. The stoichiometric composition and cationic distribution of the grown crystals are determined using Energy Dispersive X-Ray Analysis (EDAX) technique. The functional groups present in the crystals are identified by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectral studies. Thermal studies confirm the presence of five water molecules in the IST and CuDST crystals.Optical studies reveal that the crystals are transparent to visible and near Infrared (IR) wavelengths. Doping is observed to cause an increase in the peak absorbance in Ultraviolet (UV) region. Both IST and CuDST crystals show low absorbance in the entire visible region, indicating their usefulness in Nonlinear Optical (NLO) applications. The optical transmittance of the IST crystal is seen to increase on doping. Both IST and CuDST crystals show bandgap energies suggestive of their insulating nature, indicating their usefulness in electronic applications. The Voltage-Current (V-I) characteristics of the crystals show that the electrical conductivity of CuDST crystals is larger than the conductivity of IST crystals.