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Studies on optical, electrical, mechanical and theoretical investigation of 4-nitro-benzoic acid (3-ethoxy-2-hydroxy-benzylidene)-hydrazide: A novel Schiff base organic NLO material
摘要： New organic non-centrosymmetric Schiff base material 4-Nitro-benzoic acid (3-ethoxy-2-hydroxy-benzylidene)-hydrazide was synthesized and grown as single crystal by slow evaporation solution growth technique. Single crystal X-ray diffraction reveals the noncentrosymmetric nature of the grown crystal with space group Pna21. The nonlinear efficiency of the grown material was studied by Kurtz-Perry powder technique and found to be 0.7 times that of KDP. The photoluminescence emission of the grown crystal shows emission at 360 nm. The mechanical stability of the crystal was examined by Vicker’s microhardness study and the yield strength of the material was calculated. Low dielectric constant at higher frequencies was observed from dielectric measurements. Reduction in charge carriers when the sample was illuminated by halogen lamp proves the negative photoconductivity of the sample. In addition, quantum chemical calculations were carried out using density functional theory for the NEH molecule optimized at B3LYP/6-31+G (d, p) basis set to calculate its frontier molecular orbital, Electrostatic potential and Mulliken charge analysis.
关键词： DFT,Dielectrics,Schiff base,non-centrosymmetric,Crystal growth
更新于2025-09-23 15:23:52
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Temperature dependence of luminescence properties in Li2WO4 single crystal grown by Bridgman method
摘要： Transparent Li2WO4 single crystal was grown by vertical Bridgman method. The phase identification, Fourier transform infrared spectra, thermal behavior, and optical transmission spectra of Li2WO4 crystal had been studied in detail. The luminescence properties as a function of temperature were investigated systematically. The transmissivity of as-polished crystal samples with the thickness of 2.0 mm, 4.0 mm, and 6.0 mm reached 85–89%, 81–85%, and 78–81% in 400–800 nm wavelength range, respectively. Li2WO4 crystal has wide luminescence peaks around 626 nm, 574 nm, and 543 nm at the ambient temperature of 30 K, 50 K, and 75 K, respectively. The luminescence peaks are ascribed to the intrinsic luminescence emission of tetrahedral [WO4]2-. The emission line width presents an obvious broadening with the increasing temperature. The maximal luminescence intensity increases with the ambient temperatures cooling down. The luminescence decay times monotonically decrease with the temperature increasing in temperature range of 30–75 K. The decay times at 30 K, 50 K, and 75 K correspond to 97.92 m s, 30.16 m s, and 1.97 m s, respectively, while maintain a constant around 1.80 m s in 75–300 K.
关键词： Bridgman method,Crystal growth,Li2WO4,Luminescence
更新于2025-09-23 15:23:52
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Investigations on the quantum chemical studies and physico-chemical properties of an opto-electronic material 1-Allyl-2-Aminopyridine-1-ium bromide
摘要： In the present work, the dual approach of quantum chemical studies and experimental characterizations of the title compound 1-Allyl-2-Aminopyridine-1-ium bromide (1A2APB) were carried out for the first time. The molecular geometry of 1A2APB was optimized by density functional theory (DFT) using B3LYP/6-311++G (d,p) basis set. The optimized geometric structural parameters were compared with the experimental findings and discussed. The dipole moment (μ) and first hyperpolarizability (β) were calculated to predict the NLO behavior. The frontier molecular orbital (FMO), molecular electrostatic potential (MESP), Mulliken atomic charge and thermodynamic properties were investigated to get a better insight of the molecular properties. Stability of the compound arising from hyper-conjugative interactions, intra-molecule re-hybridization and charge delocalization within the molecule were analyzed using NBO analysis. Further, 1A2APB was synthesized and good quality single crystals were grown by slow evaporation technique. Studies such as microanalysis and powder XRD were performed to ascertain material composition and phase respectively. The various characteristic functional groups were identified through FT-IR spectroscopic analyses. The NLO efficiency was measured to be about greater than 5 times that of standard KDP. Thermal behaviors were explored by the simultaneous TG/DTA-DSC thermograms. The UV–Vis–NIR spectral data and fluorescence spectrum were recorded to explore the optical transmission and emission properties respectively. The dielectric properties were evaluated as a function of frequency at various temperatures. The photoconducting nature was analyzed through photoconductivity measurement. The Vicker’s microhardness test was performed at room temperature from which the mechanical stability was analyzed through the classical Meyer’s relation.
关键词： Photoconductivity,Powder XRD analysis,DFT calculations,Organic materials,Non-linear optics,Crystal growth
更新于2025-09-23 15:23:52
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Utilizing an In Situ Reduction in the Synthesis of BaMoOF5
摘要： A new molybdenum containing oxyfluoride, BaMoOF5, space group Cmcm with lattice parameters of a = 7.1445(3), b = 6.7894(3), c = 10.1969(4), was synthesized via a mild hydrothermal crystal growth method. The synthesis resulted in high-quality single crystals of the title material, which were characterized by single-crystal X-ray diffraction. The structure is discussed in detail.
关键词： Crystal growth,In situ reduction,Mild hydrothermal
更新于2025-09-23 15:23:52
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Shining light on growth-dependent surface chemistry of organic crystals: a polarised Raman spectroscopic and computational study of aspirin
摘要： Understanding and controlling crystal surfaces is a critical problem in contemporary materials science. Organic crystal surfaces present the additional complexity of multiple terminations with different functional groups. These alternate terminations influence the surface chemistry and exert control on many material properties. While established tools for surface characterization exist, few provide the chemical information required to unambiguously identify functional groups. Polarized Raman spectroscopy is a versatile tool that can provide detailed chemical information on molecular materials, and, when used in a microscope configuration, can be used to map substrates on a micron scale. In this work, we demonstrate the use of polarized Raman to study the surface chemistry of aspirin. By analyzing crystals grown under a variety of conditions, we relate the growth solvent to the surface termination and reconcile the conflicting results in the literature on the nature of the <100> surface. Our results are supported by detailed first-principles modelling of the surfaces and their vibrational spectra. This study establishes the potential of polarized Raman microscopy as a tool for organic surface science that, when combined with predictive modelling, provides a powerful means to understand and ultimately control surface chemistry.
关键词： aspirin,first-principles modelling,crystal growth,polarized Raman spectroscopy,surface termination,lattice dynamics
更新于2025-09-23 15:23:52
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High infrared transmittance CdS single crystal grown by physical vapor transport
摘要： Φ55 × 15 mm2 CdS bulk single crystal with high infrared transmittance was grown by physical vapor transport. The single crystal has a consistent structure from top to bottom, which was confirmed by X-ray diffraction. The (002) full-width at half-maximum of the X-ray diffraction was measured to be 60.00 arcsec, indicating a good quality of the structure. Hall mobility, specific resistivity, and carrier concentration for the top and bottom of the crystal were observed as well. Transmittance for the CdS single crystal was measured to be higher than 70% from 2.5 to 4.5 μm, making the single crystal an important candidate for infrared window materials. Furthermore, the absorption mechanism of the CdS single crystal was analyzed.
关键词： physical vapor transport,X-ray diffraction,semiconducting materials,single crystal growth
更新于2025-09-23 15:23:52
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Growth, optical, mechanical and thermal behavior of unidirectionally grown L-Glutaminium p-Toluenesulfonate crystal
摘要： Organic crystal of L-Glutaminium p-Toluenesulfonate (LGPT) was grown unidirectional by Sankaranarayanan and Ramasamy (SR) method. The grown crystal belongs to monoclinic crystal system with noncentrosymmetric space group P21. High resolution XRD confirms crystalline perfection of the grown crystal. Optical transmission shows that unidirectional grown crystal has higher transmittance and the lower cut-off wavelength is 290 nm. The emission wavelength of grown crystal is 410 nm and emission region is confirmed by luminescence spectra. The laser damage threshold value of unidirectional crystal has increased by 0.3 GW/cm2. The grown LGPT crystals belong to hard material category and it confirms the normal indentation size effect. The grown LGPT crystal is thermally stable upto 165 oC and decomposition of the molecules were elucidated by using TGA and DSC. Powder second harmonic generation measurement confirms the efficiency of the grown LGPT crystal is 0.8 times that of KDP.
关键词： Nonlinear optical materials,Crystal growth,Recrystallization,Optical properties
更新于2025-09-23 15:23:52
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Tuning optical properties of cadmium thiourea acetate nonlinear optical crystal exploiting organic ligand of L-proline
摘要： Modifying optical properties of crystal is very fundamental need for designing various photonic devices, hence in the current investigation, the L-proline (LP) has been firstly doped in cadmium thiourea acetate (CTA) crystal with the aim to optimize the UV–Visible, second harmonic generation (SHG) efficiency, luminescence and third-order nonlinear optical (TONLO) properties of CTA crystal. The pure and doped CTA crystals have been grown by slow solvent evaporation technique at 35°C. The structural parameters of grown crystals have been determined using the single crystal X-ray diffraction technique. The incorporation of LP in CTA crystal matrix has been confirmed by Fourier transforms infrared analysis. The UV–Visible studies have been employed within the wavelength range of 200–900 nm to explore the enhancing impact of LP on CTA crystal. The LP doped CTA crystals were subjected to Kurtz–Perry test and Z-scan analysis to identify the nonlinear nature of studied crystals. The SHG efficiency of LP-CTA crystal shows significant increase owing to enhanced charge transfer over the organic ligand of LP. The laser-induced TONLO properties of LP-doped CTA crystal have been determined at 632.8 nm. The nature of nonlinear refraction and absorption has been explored by close and open aperture Z-scan configuration. The magnitude of nonlinear refraction (n2), absorption coefficient (β), cubic susceptibility (χ3) and figure of merit has been determined using the transmittance data. The color-centered luminescence studies have been carried out which established the prominent redshift in peak maxima of emission wavelength of CTA crystal due to doping of LP. Comparative analysis of pure and doped crystal confirmed the dominance of LP doping.
关键词： optical studies,TONLO parameters,Crystal growth,Z-scan analysis
更新于2025-09-23 15:22:29
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Fabrication and Optical Properties of 2at.%Yb:LuYAG Mixed Crystal through Nanocrystalline Powders
摘要： Ytterbium doped Lu1.5Y1.5Al5O12 (LuYAG) nanocrystalline powders were synthesized by a wet chemical mixed precipitant co-precipitation (MPP) method, and then the mixed crystal of Yb:LuYAG was grown in an optical floating zone (OFZ) furnace at the speed of 6–10 mm/h, using a [111] oriented YAG seed crystal. The transmittance of the polished LuYAG crystal is close to the ideal value of LuAG or YAG. The X-ray rocking curve shows complete symmetry and the full width at half maximum (FWHM) is 10 arc-second, indicating the good quality of as grown Yb:LuYAG multicomponent garnet crystal. The thermal luminescent spectrum at room temperature shows four deep energy traps at around 1–1.3 eV. X-ray excited luminesce (XEL) spectra is measured to characterize the existence of LuAl or YAl shadow defects in the bulk single crystal. The emission peak at around 320 nm indicates that the LuYAG crystal prepared by OFZ have lower concentrations of antisite defects (AD) with respect to its Czochralski counterpart.
关键词： crystal growth,optical floating zone,LuYAG,optical properties
更新于2025-09-23 15:22:29
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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Compact Solid State Neutron-Gamma Detectors for Backpack or Handheld Instruments
摘要： In this paper, we report on the characterization of detectors constructed at RMD using 1-inch, 1.5-inch, and 2-inch diameter right cylinders of CLYC and CLLBC crystals coupled to arrays of silicon photomultipliers (SiPM). Detectors constructed with small volume CLLBC crystals coupled to a 12 mm × 12mm total area SiPM array show an excellent energy resolution of ~3% at 662 keV and a large volume CLYC crystal when coupled to a 24 mm × 24 mm area array shows an energy resolution of ~6.6% at 662 keV. Both detectors show pulse shape discrimination capabilities.
关键词： Gamma-ray detection,crystal growth,elpasolites,energy resolution,neutron detection,scintillation detector,CLLBC,CLYC,thermal neutrons
更新于2025-09-23 15:22:29