4-(3-Eth­oxy-4-hydroxy­styr­yl)-1-methyl­pyridinium tosyl­ate monohydrate

In the title compound, C16H18NO2 +·C7H7O3S−·H2O, the dihedral angle between the pyridyl and benzene rings of the pyridinium cation is 0.2 (1)°. The benzene ring of the tosyl­ate anion makes a dihedral angle of 4.8 (2)° with the best mean plane of the pyridinium cation. The pyridinium cation and the tosyl­ate anion are hydrogen bonded to the water mol­ecule, and the crystal packing is further stabilized by inter­molecular C—H⋯O and π–π inter­actions [centroid–centroid separations of 3.648 (3) and 3.594 (2) Å

Laser Cleaning of Grey Cast Iron Automotive Brake Disc: Rust Removal and Improvement in Surface Integrity

There is a great need for removal of rust and surface damage from corroded engineering parts. This enables the retention of strength and increased longevity of metals and alloys in general. The use of lasers for cleaning, polishing and ablation has proven to be effective and promising overtime. This research is focused on a parametric study of laser cleaning a corroded grey cast iron brake disc. A continuous wave CO2 laser having a wavelength of 10.6μm was used for the study. A systematic approach was employed for the experiments where one parameter was changed while other parameters remained constant. Additional effects of laser cleaning were predicted by a Gaussian process regression approach. The results revealed that the best parameters which cleanly removed the rust were 60W of laser power, 900mm/s traverse speed, and a spot size of 722μm. The enhancement of surface microhardness of laser cleaned specimen was 37% compared to the rusted specimen surfaces. The roughness of the laser cleaned surface was, 1.29μm while the rusted surface comprised of 55.45μm (Ra). Microstructural analysis showed a presence of randomly distributed graphite flakes surrounded by a pearlitic matrix containing ferrite and cementite after laser cleaning. This was similar to that of the un-rusted surface. The hardness, roughness and microstructural content were in close relation with the respective properties of the unrusted automotive brake disc. This showed that the mechanical and physical properties of the brake disc were not altered negatively during the laser cleaning process. Implementation of the laser-cleaning technique in automotive and manufacturing industries should be embraced as it provides a faster, safer and cheaper way of enhancing the surface integrity of components and also paves way for other surface enhancement methodologies to be applied such as blast cleaning or laser shock cleaning for inducing extra strength, by beneficial residual stresses

Growth and Dielectric Properties of 1,3-bis(4-methoxyphenyl)prop-2-en-1-one Organic Single Crystal

International audienceHigh-quality single crystal of 1,3-bis(4-methoxyphenyl)prop-2-en-1-one (BMP) has been grown by the vertical Bridgman technique. Calculated the grain size of BMP single crystal from powder XRD. 1 H NMR spectrum was recorded to confirm the presence of protons in the synthesized compound. The dielectric constant and dielectric loss of the grown crystal was studied as a function of frequency with different temperatures and the results are discussed. Introduction. In the past few years, optoelectronic materials have prompted researchers to grow large size of organic single crystals for advanced high technology devices. NLO has emerging as one of the most attractive field of research in view of vital applications such as high speed information processing, optical data storage, optical communications and frequency conversion [1, 2]. The high dipole moment generally leads to the molecules packing in centrosymmetric arrangements and SHG responses in these systems become zero. Therefore, one requires a highly hyperpolarizable molecule aligned in a head-to-tail fashion, connected through strong hydrogen bond interactions, crystallizing in noncentrosymmetric structures and produce high second harmonic generation efficiency. Chalcones are interesting organic NLO materials that show good crystallizability, high SHG conversion efficiency compared to urea [3, 4]. In recent years, researchers focused on the growth of high quality organic single crystals. The organic single crystals can be grown by different techniques. In certain organic materials, the solution growth techniques such as slow cooling and slow evaporation take more time to crystallize and difficult to grow large size crystals and sometimes the solvent inclusion can reduce the optical property of the crystal [5]. The melt growth technique is one of the techniques widely used to grow organic and inorganic single crystals. Bridgman technique is the simplest and best technique for the growth of large size good quality transparent crystals from melt in the stipulated period [6]. This paper, deals with the growth of 1,3-bis(4-methoxyphenyl)prop-2-en-1-one (BMP) by two zone vertical Bridgman technique and its rest of the characterizations 1 H NMR and Dielectric properties

Chemical Etching, AFM, Laser Damage Threshold, and Nonlinear Optical Studies of Potential Nonlinear Optical Crystal: Bis (L-Glutamine) Potassium Nitrate

A novel semiorganic nonlinear optical crystal bis (L-glutamine) potassium nitrate (BGPN) grown by slow evaporation technique at ambient temperature. The grown crystal surface has been analyzed by chemical etching and atomic force microscopy (AFM) studies. Amplitude parameters like area roughness, roughness average, valley height, valley depth, peak height, and peak valley height were measured successfully from AFM studies. Etching studies were carried out by various solvents like water, methanol and ethanol. The etching study indicates the occurrence of different types of etch pit patterns like striations and steplike pattern. The laser damage threshold energy has been measured by irradiating laser beam using a Q-switched Nd: YAG laser (1064 nm). Second harmonic generation (SHG) studies have been performed by famous Kurtz powder technique with reference to standard potassium dihydrogen phosphate single crystals (KDP). It is found from this technique that SHG efficiency of BGPN is in comparison to that of standard KDP crystals

Modeling and Simulation of Dual Gratings based Ultrathin Amorphous Silicon Solar Cells

International audienceWe present the modeling and simulation of a 50 nm ultrathin amorphous silicon solar cell using RCWA method. Optimized solar cell design showed enhanced cell efficiency up to 16.02 and 15.2% for the TE and TM polarization cases. An enhancement in optical performance is found that is associated with efficient light trapping design. The proposed design is observed to be supported with photonic and plasmonic modes. We have also explored the field distribution within the solar device with Fabry-Perot (FP) resonance and surface plasmon polariton (SPP) modes. Introduction. Nowadays, there is a trend of making silicon solar cellsby employing thin absorption layer in order to reduce the fabrication cost. But this absorber layer is inefficient for the absorption of high wavelength light [1].According to the literature, the penetration depth of the photons in 180µm thick silicon solar cell was observed to be 3mm within the wavelength range 900-1100 nm. Therefore, the challenging issue is to design an efficient light trapping structure which can reuse the unabsorbed light coming after crossing the thin active region. Among various light trapping schemes, grating based design is found to be promising for the photons trapping. However, the metal and dielectric gratings at the bottom and top respectively are demanded for the better harvesting of light [2]. Ge et al. have proposed a solar cell design based on metallic gratingswithone-dimensional (1D) photonic crystaland observed an enhancement in the optical path length. They have obtained a wide range of optical absorption for both TE and TM polarization modes using rigorous coupled wave analysis (RCWA) method.The designed hybrid solar cell showed enhancement in photon absorption over the entire spectral region irrespective to the angle of incidence[3].Mutitu et al.havepresented a design and fabrication of hybrid dielectric-metallic back reflectors for amorphous silicon solar cells and reported the enhanced reflectance with the use of more distributed Bragg layer (DBR) pairs. This proposed idea of solar cell design has explored the experimental realization of thin filma-Si solar cells using hybrid dielectric-metallic back surface reflector[4].Abass et al. have numerically studied the complex dual-interface grating systems (plasmonic Ag grating at the bottom and dielectric ITO gratings at the top)to enhance light absorption in silicon thin film solar cells. The proposed grating could felicitate the effect of both plasmonic and photonic modes[5].Theuring et al.have presented the design and fabrication of plasmonic and photonic light trapping structure by using metallic (Ag) and non-metallic (SiO2) nanoparticle respectively. The solar cell integrated with SiO2 nanoparticles could give good result as comparison to the solar cell based on Ag nanoparticles [6]

Performance enhancement of thin film silicon solar cells based on distributed Bragg reflector & diffraction grating

The influence of various designing parameters were investigated and explored for high performance solar cells. Single layer grating based solar cell of 50 μm thickness gives maximum efficiency up to 24 % whereas same efficiency is achieved with the use of three bilayers grating based solar cell of 30 μm thickness. Remarkably, bilayer grating based solar cell design not only gives broadband absorption but also enhancement in efficiency with reduced cell thickness requirement. This absorption enhancement is attributed to the high reflection and diffraction from DBR and grating respectively. The obtained short-circuit current were 29.6, 32.9, 34.6 and 36.05 mA/cm2 of 5, 10, 20 and 30 μm cell thicknesses respectively. These presented designing efforts would be helpful to design and realize new generation of solar cells

Growth and Etching Studies of Cadmium Mercury Thiocyanate Single Crystals Grown by Gel Technique

International audienceSingle crystals of Cadmium mercury thiocyanate CdHg(SCN)4, a bimetallic thiocyanate complex material have been grown in silica gel using gel technique by the process of diffusion. Colourless transparent crystals of size 10mm x 3.1mm x 3.2mm have been obtained. The grown crystals were subjected to single crystal X-ray diffraction and high resolution X-ray diffraction studies. The crystal structure belongs to tetragonal system. Etching studies were made on the grown crystal to analyze the structural imperfection of the crystal. The Second harmonic generation efficiency of the grown crystal has been determined using Kurtz powder technique in comparison with Urea. Its efficiency is found to be 6.2 times greater than that of Urea

Bulk Crystal growth and Characterization of Organic Nonlinear Optical Crystal: 2-(2,4-dimethoxybenzylidene) malononitrile (DMM)

International audienceBulk organic nonlinear optical single crystal of 2-(2,4-dimethoxybenzylidene) malononitrile (DMM) with size up to 24×18×13 mm 2 was successfully grown by slow evaporation solution growth technique. The single crystal X-ray diffraction studies of the grown crystal exhibit that the crystal belongs to a monoclinic system with P21/n space group. The FT-IR spectrum confirms the various functional groups present in the grown crystal. The optical properties of the grown crystals were analyzed by UV–Vis-NIR spectral analysis. Third-order nonlinear optical behaviour of the title crystal was studied by Z-scan technique. All the finding results in the present work indicate that DMM has a potential application as a useful NLO candidate. Introduction. In recent years, organic non-linear optical (NLO) crystals have gained considerable attention due to their relatively high nonlinearity and fast response. Particularly, third order nonlinear optical (TONLO) organic materials have gained much consideration because of their promising applications in optical switching, optical data processing, optical limiting, signal processing and ultra-fast optical communications, etc [1,2]. The centrosymmetric organic crystals with good stability lead to third order susceptibility (χ (3)) and higher nonlinear absorption coefficient (β) and fast response time for nonlinear optical properties. However, only very few organic materials could so far be crystallized in reasonable crystal size and optical grade to realize various applications. For the first time, we present here investigations on the bulk growth of DMM organic crystals and its different characterizations