Synthesis, Growth and Characterization of Nonlinear Optical Single Crystal of Serine Succinate

Nonlinear optical single crystal of Serine Succinate (SSA) was grown from a mixed solvent of water, ethanol and methanol. Since amino acid exhibits nonlinear optical property, it is of interest to dope them in serine. The overwhelming success of molecular engineering in controlling nonlinear optical properties in last decade has prompted better initiative in crystal engineering. In the present study single crystals of serine doped with succinic acid in different ratios have been grown by slow evaporation solution growth method. Grown serine succinate crystals were subjected to various characterization techniques. The cell parameters of the grown crystals were characterized by X-ray diffraction analysis. FT-Raman spectral studies were carried out on the SAA grown material to confirm the synthesized compound and the functional groups of serine succinate single crystal were identified from FTIR analysis. The optical transparency and upper cut off value of UV transmission spectrum of SSA crystal were recorded. Fluorescence study was also carried out for the grown materials. The mechanical hardness was estimated by Vickers’s micro hardness tester. The second harmonic generation (SHG) of the grown crystal was confirmed by Kurtz powder technique. Thermal properties of serine succinate crystal were evaluated with thermogravimetric, differential thermal and differential scanning calorimetric analyses. The SEM studies were also reported.

CONTROLLING THE SURFACE COMPOSITION OF PCBM IN P3HT/PCBM BLEND FILMS BY USING MIXED SOLVENTS WITH DIFFERENT EVAPORATION RATES

The surface composition of poly（3-hexylthiophene-2,5-diyl） and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester （P3HT/PCBM） blend films could be changed by controlling the film formation process via using mixed solvents with different evaporation rates. The second solvent, with a higher boiling point than that of the first solvent and much better solubility for PCBM than P3HT, is chosen to mix with the first solvent with a lower boiling point and good solubility for both PCBM and P3HT. The slow evaporation rate of the second solvent provides enough time for PCBM to diffuse upwards during the solvent evaporation. Thus, the weight ratio of PCBM and P3HT （mpcBM/mp3HT） at surface of the blend films was varied from ca. 0.1 to ca. 0.72, i.e., it increases about seven times by changing from single solvent to mixed solvents. Meanwhile, the mixed solvents were in favor to form P3HT naonofiber network and enhance phase separation of P3HT/PCBM blend films. As a result, the power conversion efficiency of the device from mixed solvents with slow evaporation process was about 1.5 times of the one from single solvents.

Electrical and mechanical studies on ferroelectric lithium rubidium sulphate crystals

Slow evaporation method was used to grow single crystals of lithium rubidium sulphate with high transparency.Single crystal X-ray diffraction analysis shows that at room temperature,the crystal belongs to a monoclinic system with the space group P21/n.Some physical parameters like plasma energy,Penn gap,Fermi energy and electronic polarizability have been evaluated for the grown crystal.The relation between electronic polarizability and diamagnetic susceptibility for the crystal has been established on the basis of Kirkwood’s semiempirical equation.The ac conductivity and dielectric behavior of the grown crystal were systemically investigated as a function of frequency and temperature.The title compound obeys Jonscher’s power law relations:
ð(ω)=σo+Aω^(s),with exponent s<1.From the conduction study,it is observed that both small and large polarons take part in conduction process,and at low temperature,both the band and hopping mechanisms are responsible for conduction.From impedance and modulus studies,it is observed that only one conduction relaxation is observed in the crystal at low frequency.The activation energy of the dielectric relaxation(0.41 eV)and that of the conduction(Econd¼0:43 eV)are in agreement,as a result,there is no difference among the conduction and relaxation species at high temperature.Differential scanning calorimetric analysis of the crystal shows three endothermic peaks at 166℃,185℃,and 202℃,from which various thermodynamic parameters such asΔH,ΔS andΔC_(p) have been calculated.From Vickers hardness test,we have determined the mechanical strength,and other parameters which include fracture toughness,brittleness index,yield strength,and stiffness constant for the crystal.