Synthesis, growth, thermal, mechanical and optical studies of piperazinium based cupric sulfate (PCS) single crystals: A third order nonlinear optical material

Abstract

A third order nonlinear optical (NLO) good quality Piperazinium based cupric sulfate (PCS) single crystals has been grown successfully from homogeneous solution by slow evaporation technique using double distilled water at room temperature. The average dimensions of the as grown crystals are up to 36×30×15mm3 within a period of 35 days. The grown single crystals were subjected to powder X-ray diffraction (XRD) to confirm the crystalline quality. Single crystals X-ray diffraction represents, the PCS crystal belongs to the monoclinic system (P), with unit cell parameters a=6.87Å, b=10.20 Å, c=11.92Å and V=834A°3. Existence of major functional groups in PCS single crystal has been identified by FTIR analysis. The thermal properties of PCS single crystals were analyzed from TG−DTA curves and the compound is thermally stable up to 134°C. The UV–vis absorption studies indicate the PCS single crystals are optically transparent up to 60.88% at 496nm with the cut-off wavelength 258nm. From the Tauc's plot optical band gap is estimated to be (Eg)5.30eV.The extinction coefficient (k) vs. wavelength relation for PCS single crystals have minimum absorption of light around 493nm. The refractive index (n0) of PCS single crystals has least value for blue and green light; it is gradually increased till red light. It is supported by reflectance vs. wavelength calculation with high reflectance at same wavelength range. The photoluminescence (PL) emission spectra for as grown crystals represent prominent emission around 440−470nm depicting blue emission with 244nm excitation wavelength. The electric field response of PCS single crystals has been studies in terms of dielectric constant and dielectric loss as a function of frequency and temperature, the results were discussed. The mechanical stability of the grown crystals at room temperature has investigated with Vicker's micro hardness test and evaluated various mechanical parameters such as Hv,Kc,σv andC11.Hardness number increased with load.PCS single crystals exhibits RISE behavior and belong to soft category. The third order nonlinear optical nature of PCS single crystals was studied using Z−scan technique. The negative nonlinear refractive index (n2) of the crystals indicates self-defocusing effect. The nonlinear absorption coefficient (β) and third order nonlinear optical susceptibility (χ(3)) were also calculated and discussed from the above technique.