Recent Trends in Advanced Materials

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Authors: K. Russel Raj, P. Murugakoothan
Abstract: Abstract. An organic NLO material L-Valinium Picrate (LVP) doped with nickel sulphate (5 mol %) was synthesized and crystals were grown from aqueous solution using slow evaporation method. The solubility, metastable zone width and induction period were determined. The second harmonic generation (SHG) relative efficiency of the LVP (Ni2+) 5 mol% is found to be 260 times higher than that of a standard reference material potassium dihydrogen phosphate (KDP) and 43 times of that of urea.
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Authors: P. Vivek, P. Murugakoothan
Abstract: Single crystal of organic material Methyl N- phenylsuccinamate (MPS) has been grown by the slow evaporation technique using methanol as a solvent. The crystal belongs to orthorhombic system with non centrosymmetric space group Pna21. Optical transmittance and second harmonic generation efficiency of the grown crystals have been studied by UV-vis-NIR spectrum and Kurtz powder technique respectively. The transmittance of MPS crystal has been used to calculate the refractive index (n), the extinction coefficient (k) and reflectance (R). The laser induced surface damage threshold for the grown crystal has been measured using Nd:YAG laser. The mechanical behaviour of the MPS crystal has also been analyzed.
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Authors: S. Sudhahar, M. Krishna Kumar, R. Mohan Kumar
Abstract: Rare earth doped potassium hydrogen phthalate (KHP) single crystals have been grown by slow evaporation technique. Single and powder X-ray diffraction analysis confirms the structural and crystallinity of grown crystals. The functional groups of pure and doped KAP crystals have been identified by FTIR spectral studies. UV-Vis studies explore the optical transmittance of the grown crystals in the entire visible region. Nonlinear optical property of the pure and doped KHP crystals was confirmed by Kurtz-Perry powder test.
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Authors: S. Vetrivel, R. Rajasekaran
Abstract: Single Crystals of 20% of Zinc doped L- Proline Cadmium chloride [Zn(20M):LPCC] and 40% of Zinc doped L-Proline Cadmium chloride[Zn(40M):LPCC]were successfully grown from aqueous solution by slow evaporation method at room temperature. The grown crystals of [Zn(20M):LPCC] and [Zn(40M):LPCC] have dimensions 47x14x3.7 mm3 and 36x9.5x4.2 mm3 respectively. The single crystal XRD, powder XRD patterns were recorded and indexed for crystalline nature of grown materials. The presence of functional group has been confirmed by FTIR analysis. The optical transmission spectrum has been recorded in wavelength region 100nm to1000nm.The thermal properties were studied by TGA/DTA. The second harmonic generation (SHG) was carried out and it reveals the NLO property of the crystals. The electrical properties were studied by dielectric studies.
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Authors: P.S. Latha Mageshwari, R. Priya, S. Krishnan, V. Joseph, S. Jerome Das
Abstract: Excellent and optically transparent good quality single crystals of cadmium chloride doped with lithium sulphate monohydrate (LS) were grown in aqueous solution by slow evaporation technique at room temperature. Single crystal X-ray diffraction analysis confirmed the changes in the lattice parameters of the cadmium chloride lithium sulphate (CCLS). The functional groups present in the CCLS crystals were determined qualitatively by using Fourier transform infrared (FTIR) spectroscopy. Optical absorption studies revealed that doped crystals acquire very low absorption in the entire visible region. Dielectric measurements show that the dielectric constant and dielectric loss of doped crystals decreases with increase of frequency.
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Authors: P. Malliga, R. Umamaheshwari, A. Joseph Arul Pragasam
Abstract: A single crystal of L-alanine hydrogenchloride doped with thiourea has been synthesized and grown successfully by slow evaporation technique at room temperature. The cell parameters were determined by the X-ray diffraction analysis. The UV - visible spectral analysis has been recorded to study the optical transmittance in the range from 200nm to1200nm.The Fourier transform infrared analysis identified various functional groups present in the material.The dielectric measurement was made as function of frequency.HR-SEM studies confirms the inclusion of the dopant thiourea. The second harmonic generation efficiency has been determined by Kurtz powder test.
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Authors: S. Arulmozhi, J. Madhavan
Abstract: L- Histidinium Perchlorate, a semi organic nonlinear optical material was grown by solution growth method. The absorption studies show minimum absorption in the entire visible region. The optical band gap (Eg) value of the grown crystal is obtained from the tauc’s plot of (αhν)2 vs hν which was determined by extrapolating the linear region of the curve to the hν axis where (αhν)2=0. Furthermore linear optical parameters such as Extinction coefficient, Reflectance, Refractive index, Complex dielectric constant and Optical conductivity are calculated and its variation with incident photon energy is analyzed. Second Harmonic Generating (SHG) efficiency of the candidate material was determined by Nd:YAG Q-switched laser Kurtz powder techinqe and its 3.19 times greater than KDP.
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Authors: Rajendra Deshmukh, Manoj Malik, Sanmesh Parab
Abstract: The electro-optical characteristics of dye-doped polymer dispersed liquid crystals (PDLCs) have been investigated for display applications. The PDLC samples were obtained by polymerization induced phase separation of the nematic liquid crystal (LC)-dye-prepolymer mixtures under UV illumination with a constant intensity. The optimum conditions for the scattering characteristics of the dye-doped PDLC films as function of the dye concentration have been examined. It was seen that the phase separation and segregation of LC droplets is dependent on the amount of dye used. LC droplets in dye-doped PDLC films exhibit various configurations at lower and higher applied electric field when observed in situ under polarizing optical microscope. The effects of morphology on the electro-optical properties were examined. Experimental results indicate that the driving voltage and contrast ratio were affected considerably by the amount of dye. UV-VIS spectroscopy results showed that the molecular orientation of dye in LC droplets can be controlled to induce nonlinearity in these materials. The results showed that the dye concentration can be optimized to obtain promising electronic materials with minimum threshold and high contrast for display applications.
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Authors: Arumugam Manohar, Kuppukannu Ramalingam, Kottamalai Karpagavel, Gabriale Bocelli
Abstract: Bond valence sum (BVS) analysis is used by many researchers to determine the oxidation state of metal ions in solids based on crystallographically determined metal-ligand bond distances. In this paper, bond valence sums (BVS) have been calculated for a series of mixed ligand complexes involving Nickel(II)dithiocarbamates and phosphorous donor ligands. The BVS values are calculated first time for the complexes whose crystal structures have been reported from our laboratory and a few others reported from other laboratories. The calculated values show that the BVS values are higher than the expected formal oxidation state of +2. The higher values observed in the complexes support the fact that the Ni-S, Ni-P bonds are more covalent and the back bonding effects are very highly pronounced.
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Authors: N.K. Siji Narendran, K.R. Reshma, P. Sudheesh, K. Chandrasekharan
Abstract: We report the effect of electric field on third order nonlinear optical properties of Hydrazone (Hz) doped Polymethyl methacrylate (PMMA) films. The films were prepared by solution casting method. Poling of films was done by corona discharge. Single beam Z-scan technique with 7ns Nd: YAG laser pulses at 532nm were employed for the measurements. Third order susceptibility of films was measured with an emphasis on the applied electric field. We also demonstrated the second harmonic generation in the corona poled films.
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