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Growth and study of nonlinear optical P-dimethyl-aminobenzaldehyde crystal for photonic device application
摘要： Pera dimethyl-aminobenzaldehyde (p-DMAB) is a well known aromatic compound with nonlinear optical (NLO) properties in various application fields such as optoelectronics, photonics etc. The single crystal of p-DMAB is grown by slow evaporation technique (Constant Temperature Bath) at room temperature. These grown crystals are good in size with transparent appearance. The grown crystals are characterized using XRD, FTIR spectroscopy, Elemental analysis, UV-Spectroscopy, Second Harmonic Generation (SHG), Optical limiter behaviour, Photoluminescence (PL), Vickers hardness, Scanning Electron Microscopy (SEM). Single crystal XRD provides information about the crystal structure. The powder XRD shows that material is crystalline in nature. FTIR- Spectroscopy provides information about the relevant functional group present in the compound. CHN (Carbon-Hydrogen-Nitrogen) analysis shows appropriate composition of these elements within this material. UV-Vis study reveals that materials have wide window over the entire visible region. The observed order of refractive index points their use in anti-refracting coating devices. Good linear polarisability, susceptibility, optical conductivity data are also appropriate to decide their use in optical device fabrications. Wider optical band gap described dielectric behavior of material. Second harmonic generation test shows that material has 2.03 times greater efficiency than the reference material KDP. Moreover the emission of green light indicates that the material can be used to develop green-blue laser. Optical limiter behavior shows that material is suitable for fabrication of an optical limiter device. In PL study desecrate energy level indicates purity of grown crystals. The Vicker’s micro hardness study was also carried out on the sample. Vickers hardness test shows increment in hardness, yield strength and stiffness of material. SEM images show smooth morphology at different magnifications.
关键词： FTIR,Crystal growth,SEM,XRD,Vickers hardness,CTB method
更新于2025-09-23 15:22:29
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Driving force of crystallisation based on diffusion in the boundary and the integration layers
摘要： Crystal growth rates are notoriously difficult to predict and even experimental data are often inconsistent. By allowing for mass and energy diffusion through the molecular and thermal layers surrounding a growing crystal and for the heat effect of crystallization, a new model of crystal growth from solution is proposed and applied to crystallization of potassium chloride from aqueous solution. The driving force for crystal growth was calculated using the solubility at the interface temperature in contrast to the conventional one based on bulk temperature. A positive heat effect at the crystal interface as well as the resistances to the mass and energy transfer processes to and from the crystal surface can reduce the conventional driving force for crystal growth by more than 20%.
关键词： Crystal growth rate,Boundary layer,Driving force,Mathematical modelling,Integration (Desolvation) layer
更新于2025-09-23 15:22:29
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Numerical Analysis of Thermal Stress in Semi-Transparent Oxide Crystals Grown by Czochralski and EFG Methods
摘要： Crystal growth of oxides is generally difficult since large curvatures of the growth interface in these systems generate high thermal stress, dislocations and crystal cracking. Three-dimensional numerical modeling is applied to investigate thermal stress distribution in sapphire and langatate La3Ta0.5Ga5.5O14 (LGT) semi-transparent crystals grown by Czochralski (Cz) and Edge-defined Film-fed Growth (EFG) techniques. The analysis of thermal stress distribution in a sapphire ingot grown in a Czochralski furnace shows high von Mises stresses distributed almost symmetrically on large areas in the crystal. Thermal stress computations for piezoelectric langatate crystals grown in a Czochralski configuration show non-symmetrical von Mises distribution with higher stress on one side of the ingot. These numerical results are in agreement with experimental results showing non-symmetrical cracking at the outer surface of the crystal. 3D modeling of multi-die EFG growth of white sapphire ribbons shows that the von Mises stress is almost constant when the number of ribbons is increased from two to ten. Two models are applied to simulate the internal radiative heat transfer in the sapphire crystals: P1 approximation and the Rosseland radiation model. Numerical results show that applying Rosseland formula introduces significant errors in temperature field calculations especially in the case of the EFG configuration.
关键词： computer simulation,Czochralski,sapphire,single crystal growth,stresses
更新于2025-09-23 15:22:29
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Rational Design via Synergistic Combination Leads to an Outstanding Deep-Ultraviolet Birefringent Li2Na2B2O5 Material with Unvalued B2O5 Functional Gene
摘要： Birefringent materials, the key component to modulate the polarization of light, are of great importance in optical communication and the laser industry. Limited by their transparency range, few birefringent materials can be practically used in the deep ultraviolet (DUV, λ < 200 nm) region. Different from the traditional BO3- or B3O6-based DUV birefringent crystals, we propose a new functional gene, the B2O5 unit, for designing birefringent materials. Excitingly, the synergistic combination of Li4B2O5 and Na4B2O5 generates a new compound, Li2Na2B2O5, with enhanced optical properties. The Li2Na2B2O5 crystal with size up to 35 × 15 × 5 mm3 was grown by top seeded solution growth (TSSG) method, and its physicochemical properties were systematically characterized. Li2Na2B2O5 features large birefringence (0.095@532 nm), short DUV cut off edge (181 nm) with high laser-induced damage threshold (LDT, 7.5 GW/cm2 @1064 nm, 10 ns), favorable anisotropic thermal expansion (αa/αb = 5.6) and lowest crystal growth temperature (< 609 oC) among the commercial birefringent crystals. Moreover, the influences of the B2O5 structural configurations on the optical anisotropy were explored. The fascinating experimental results will provide a prominent DUV birefringent crystal and an effective synthesis strategy, which can facilitate the design of DUV birefringent materials.
关键词： B2O5 unit,birefringent materials,crystal growth,deep ultraviolet,optical properties,synergistic combination,Li2Na2B2O5
更新于2025-09-23 15:22:29
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Optical, electrical, structural and magnetic properties of BiSe thin films produced by CBD on different substrates for optoelectronics applications
摘要： BiSe thin films have been grown on substrates as PMMA, ITO, glass and Si wafer by using chemical bath deposition (CBD) method. Deposition temperature and time and pH are kept to be constant during the production of the thin films. The thickness of BiSe thin films, which are produced on ITO, glass, PMMA and Si wafer substrate are 513, 468, 1039 and 260 nm, respectively. According to GAXRD results, the films, which are grown on glass and PMMA substrate, have amorphous structure, but, the films, which are grown on ITO and Si wafer substrate, have peaks of Bi2Se3 crystal. Grain sizes, crystallization number per unit area and dislocation density for ITO and Si wafer substrate are calculated as 112.40 nm and 43.04 nm; 2.25×10?5 and 7.91×10?5 (1/nm2), respectively. The contact angles and critical surface tension of distilled water, ethylene glycol, formamide and diiodamethane liquids for thin films grown on glass, ITO, PMMA and Si wafers were obtained by the Zisman method. The % transmittance and % reflectance values of thin films grown on glass, ITO, PMMA are calculated as % T: 79.90, 92.76 and 67.37; % R: 6.18, 2.07 and 10.59, respectively. Eg values of thin films grown on glass, ITO, PMMA are calculated as Eg=1.92; 2.18; 1.60 eV. The extinction coefficients, refractive indexes and relative dielectric constants of thin films grown on glass, ITO, PMMA are calculated as k=0.007; 0.002 and 0.012; n=1.65; 1.34 and 1.96; ε1=0.271; 0.083 and 0.528 respectively. Sheet resistance, hall mobility, sheet carrier densities, bulk carrier densities and conductivity types for glass, ITO, PMMA and Si are 6.52×107, 6.65×101, 1.09×108 and 6.45×102 (Ω/cm2); 2.38, 1.21×10?1, 5.34 and 1.52 (cm2/V.s); 4.01×1010, 7.71×1017, 1.06×1010 and 6.34×1015 (cm?2); 4.58×1014, 1.50×1022, 1.02×1014 and 2.89×1020 (cm?3); p, n, p and p, respectively. In addition, I–V characteristics and changes of magnetoresistance values versus magnetic field of the thin films are obtained by Van der Pauw method and HEMS.
关键词： magnetoresistance,thin film deposition,optical band gap,carrier density,surface properties,crystal growth
更新于2025-09-23 15:21:21
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Growth of high purity zone-refined Boron Carbide single crystals by Laser Diode Floating Zone method
摘要： We report the growth of 4 mm diameter x 50 mm long Boron Carbide (B4C) with large single crystal regions using a Laser Diode Floating Zone (LDFZ) method at varying growth rates of 5-20 mm/hr. These materials were grown using polycrystalline B4C as a seed. Microstructural characterization shows the presence of a significant number of twinning-boundaries along the growth direction ([001]h) oriented in the (1210)h plane. At faster growth rates >10 mm/hr, the crystal orientation was reproducible, suggesting a twin-plane mediated growth mechanism. On the contrary, at slower growth rates <10 mm/hr the crystal orientation was not reproducible, suggesting a critical rate for twin-plane mediated growth to dominate. Zone refinement of these crystals led to a significant reduction of trace impurities to better than 99.999 wt % purity, at the expense of increased twinning. Powder x-ray diffraction confirms that the bulk is rhombohedral B4C, consistent with the microstructural analysis. The X-ray reciprocal space maps reveal the growth direction to be close to the [001]h direction, and the corresponding ω-rocking curve width is ~530arcsec. The rocking curve consisted of 3 distinct peaks, indicating in-plane mosaicism, consistent with the twinning observed. Berkovich nano-indentation of the key (001)h plane showed 41 ± 1 GPa hardness, with a Young’s modulus of 520 ± 14 GPa, comparable to literature reports.
关键词： A2. Single crystal growth,A1. Defects,A1. X-ray diffraction,A1. Characterization,A2. Growth from melt
更新于2025-09-23 15:21:01
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Designing Large Area Single Crystal Perovskite Solar Cells
摘要： Organic-inorganic halide single-crystal perovskite solar cells (PSCs) are promising for higher efficiency and better stability, while their development lags far behind polycrystalline counterpart. In particular, low efficiency (<5%) of large-area devices makes it challenging to be an alternative perovskite photovoltaic technology. In this perspective, we highlight the optimization of crystal growth and reduction of crystal thickness are keys to improve performance of the large-area single-crystal PSCs. After analyzing the characteristics of perovskite crystal growth methods and efficiency evolution of single-crystal PSCs, we conclude the low efficiency of large-area devices is due to conflict between low crystal quality and large crystal thickness. Then, we propose methods to grow high-quality perovskite single crystals and possible strategy to reduce the crystal thickness. Finally, investigation of key factors and exploration of large-area application are suggested to be conducted in parallel for future development of single-crystal PSCs.
关键词： large area,perovskite solar cells,single crystal,thickness reduction,crystal growth
更新于2025-09-23 15:21:01
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Phase formation and crystal growth of Ca <sub/>3</sub> TaAl <sub/>3</sub> Si <sub/>2</sub> O <sub/>14</sub> piezoelectric single crystal
摘要： Ca3TaAl3Si2O14 (CTAS) piezoelectric powders were sintered at various temperatures to investigate phase formation. The CTAS powder sintered at 1350 °C was composed of a main phase with a langasite-type structure in addition to two secondary phases, whereas the main phases of the CTAS powders sintered at 1200 and 1300 °C were the secondary phases in X-ray di?raction patterns. CTAS single crystals with a diameter of 1 in. were grown by a Czochralski method using the sintered powders, and CTAS single crystals without impurity phases could be grown using the powder sintered at 1350 °C. A higher sintering temperature of starting materials contributes to the creation of CTAS single crystals without impurity phases.
关键词： Ca3TaAl3Si2O14,piezoelectric,crystal growth,phase formation,single crystal
更新于2025-09-23 15:21:01
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Growth and investigation on novel single crystal of ?2-cyclodextrin 2, 4-dinitrophenylhydrazine for optical sensors applications
摘要： Nonlinear optical (NLO) 2, 4-Dinitrophenylhydrazine (DNPH) single crystal was grown by slow evaporation solution growth method at ambient temperature. The characterization of Powder X – Ray diffraction peaks was con?rmed the new crystalline system. Fourier transform infrared spectroscopic analysis (FTIR) was used to the identi?cation of various functional groups present in the grown crystal. The range of optical transmittance exhibited by the grown bCD-DNPH crystal was investigated by UV Visible – NIR spectral analysis. The lower cut off wavelength of the grown crystal is observed at 270 nm. The SEM ?gures are recorded in different magni?cation. It is clear that the surface of the grown crystal appears very smooth although it has pots and microcrystal on the surface. The grain boundaries are clearly seen which shows the perfect growth of the crystal. The weight percentage (wt %) of C, N and O as obtained from EDAX analysis is in concurrent with the theoretical values. The SHG ef?ciency of the grown crystal was determined.
关键词： Optical properties,X-ray diffraction,Crystal growth
更新于2025-09-23 15:21:01
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A Review: Crystal Growth for High-Performance All-inorganic Perovskite Solar Cells
摘要： Recently, halide perovskites have become one of the most promising materials for solar cells owing to their outstanding photoelectric performance. Among them, metal halide all-inorganic perovskites (CsPbX3; where X denotes a halogen) show superior thermal and light stability. In particular, the power conversion efficiency (PCE) of perovskite solar cells (pero-SCs) based on a CsPbX3 active layer has shown a steady increase from 2.7% to 19.03% with the improvement of the CsPbX3 crystal quality. In this review, we summarize methodologies that have been employed for controlling the growth of all-inorganic perovskite films so far, including precursor solution deposition, substrate modification, composition doping, and surface engineering. Furthermore, we discuss the effect of perovskite crystal characteristics on defects and perovskite film morphology, both of which are closely related to device performance. Finally, conclusions and perspectives are presented along with useful guidelines for developing all-inorganic pero-SCs with high PCE and robust stability.
关键词： light stability,halide perovskites,precursor solution deposition,all-inorganic perovskites,surface engineering,substrate modification,thermal stability,power conversion efficiency,CsPbX3,composition doping,solar cells,crystal growth
更新于2025-09-23 15:21:01