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Growth of ZnSe nanowires on quartz substrates and their photomodulated transmittance spectra
摘要： ZnSe nanowires were grown on fused quartz substrates by a vapor transport method in which the ZnSe powder is heated at 1100?C in a tube of the furnace. The scanning electron microscopy images showed that the nanowires have the average diameter of ～110 nm. The X-ray di?raction measurement indicates that the ZnSe nanowires were a single phase of zinc-blende ZnSe. The photomodulated transmittance (PT) measurements were performed for the ZnSe nanowires at temperatures between 15 and 300 K. The measured PT spectra revealed distinct structures of E0 critical point at ～2.6?2.8 eV. This E0 critical point structure was successfully explained by adding an excitonic line shape to a one-electron line shape. The temperature dependence of E0 energy was analyzed using an analytical formula that takes into account the band-gap shrinkage e?ect by the electron-phonon interaction in semiconductors. The exciton binding energy of ZnSe nanowires was determined to be 20 meV.
关键词： Photomodulated transmittance,Crystal growth,ZnSe nanowires
更新于2025-09-10 09:29:36
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Synthesis, growth, optical, mechanical and dielectric studies on NLO active monometallic zinc iodate [Zn(IO3)2] crystal for frequency conversion
摘要： The monometallic single crystal of zinc iodate [Zn(IO3)2] was grown by slow cooling technique with the dimension up to 14 x 4 x 3 mm3 in the period of 35-45 days. Single crystal X-ray diffraction (XRD) analysis shows that the zinc iodate (ZI) crystal crystallizes in monoclinic crystal system with space group P21. The various functional groups of ZI were identified by FTIR analysis. The optical absorption of the grown crystal has been ascertained by UV-vis-NIR absorption studies. Second harmonic generation (SHG) efficiency of ZI is 2.75 times greater than that of KDP sample. The microhardness test of the grown crystal suggests that the crystal possesses relatively high mechanical strength. From the mechanical test certain mechanical parameters were determined. The dielectric behavior of the ZI crystal at different temperatures with varying frequencies shows the normal behavior activity of the grown crystal. The field dependent conductivity study was carried out.
关键词： Single crystal growth,Monometallic iodate,Dielectric studies,Microhardness,optical properties
更新于2025-09-10 09:29:36
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Synthesis, crystal growth, structural, spectral, thermal, optical characteristics and density functional theory calculations of a novel third-order nonlinear optical material: 4-acetylanilinium dihydrogen phosphate (4AADP) single crystals
摘要： Single crystals of 4-acetylanilinium dihydrogen phosphate (4AADP), a novel third-order nonlinear optical material has been synthesized and successfully grown by the slow evaporation solution growth technique using acetone as a solvent at room temperature. The single crystal X-ray diffraction analysis implies that 4AADP crystallized into a monoclinic crystal system with the centrosymmetric space group P21/c. The molecular structure of the grown 4AADP compound was evidently established by using 1H and 13C NMR spectral analysis. The vibrational behavior of the chemical bond and discrete functional groups of the grown crystal were identified using FT-IR and FT-Raman spectral analysis. UV-Visible-Near Infrared spectral analysis shows that the grown crystal was highly transparent in the entire visible range above 365 nm. The 4AADP compound was thermally stable up to 195 oC and it was ascertained by thermogravimetric and differential scanning calorimetric analysis. The photoactive behavior of the material was established from photoluminescence studies. The ionization energy (I) and electron affinity (A) were computed from the energy gap values of HOMO and LUMO orbitals respectively. The Molecular electrostatic potentials and Mulliken charges have also been calculated theoretically by applying DFT/B3LYP method. The nonlinear absorption coefficient (β), third order nonlinear refractive index (n2) and third-order nonlinear optical susceptibility (χ3) were calculated from Z-scan measurements, reveals that the grown crystal of 4AADP could serve as a promising source for nonlinear optical devices.
关键词： Crystal growth,Density functional theory,Z-scan,Thermal analysis,Spectral studies
更新于2025-09-10 09:29:36
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Ecofriendly Mg2Si-based photodiode for short-wavelength IR sensing
摘要： N-type Mg2Si single crystal ingot has been successfully grown by the Vertical Bridgman technique. The Hall Effect measurement at RT revealed a moderate Hall mobility (~ 446 cm2/Vs), electrical resistivity (~ 1.4 Ω. cm) and carrier density (~1016 cm?3) for the grown crystal. The J-V characteristics of the fabricated Au/n-Mg2Si Schottky junction and Au/Ag-doped-p-type-Mg2Si/n-type-Mg2Si/Ag pn-junction diode showed better diode behavior with higher rectifying ratio in comparison with the same reported junctions. Analysis of the experimental forward J-V characteristics of our fabricated diodes based on the thermionic emission (TE) model demonstrated that our Schottky and pn-junction Mg2Si diode exhibited much lower series resistance in comparison with the survey data, confirming that precise polishing of Mg2Si surfaces with an oil-based diamond greatly improved the contact with the evaporated metal, enabling lower interfacial resistance between the evaporated metal and Mg2Si wafer. In addition, the manufactured Mg2Si pn-junction photodiode showed a clear photoresponsivity in the wavelength range from 0.95 to 1.8 μm with a maximum zero-biased photoresponse of 14 mA/ W at 1.4 μm and a photon energy threshold of approximately 0.66 eV. These results indicate that our diode is promising to detect the SWIR light in the wavelength range from 0.95 to 1.8 μm.
关键词： Electrical properties,IR sensors,Semiconducting silicides,Single crystal growth
更新于2025-09-10 09:29:36
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Luminescence and scintillation properties of rare-earth-doped LaAlO3 single crystals
摘要： LaAlO3 perovskite single crystals doped with Ce, Eu or Tb have been grown by micro-pulling-down method. X-ray diffraction analysis confirmed low-temperature rhombohedric phase. Energy-dispersive Laue mapping revealed sub-grains in the grown crystals. For the Ce-doped crystals, very low radioluminescence efficiency was found and the observed emission was ascribed to defects. Photoluminescence spectra were significantly different from the radioluminescence ones. They were significantly quenched at room temperature and the related luminescence showed also unusually high Stokes shift. High radioluminescence efficiency was found for the Tb-doped samples and especially for the Eu-doped ones, which would point to the fact that in LaAlO3 the scintillation process is more favorable for the luminescence ions which tend to capture an electron first.
关键词： LaAlO3,crystal growth,scintillator,perovskite,luminescence
更新于2025-09-10 09:29:36
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The Crystallization Mechanism of the Octahedron-Like Ce <sub/>1-x</sub> Yb <sub/>x</sub> O <sub/>2-x/2</sub> and Ce <sub/>1-x</sub> Lu <sub/>x</sub> O <sub/>2-x/2</sub> Ceria-Based Mixed Oxide.
摘要： The crystal growth process of the octahedron-like Ce0.95(Yb or Lu)0.05O1.975 was studied by the various techniques. It has been found that the oriented attachment mechanism plays the main role during the crystal growth process. The detailed examination of the crystallite growth process was possible thanks to phosphates-addition as a thin film on the oxide surface. The octahedron-like, iso-oriented crystals are built of the small octahedral mixed oxides crystals via the oriented attachment process. The mechanism of the crystal growth of the pure ceria is probably the same but the there is no thin film of the cerium phosphate on the ceria crystals surface.
关键词： nanocrystalline materials,crystal growth,mixed oxides,Ceria
更新于2025-09-10 09:29:36
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Enhanced thermoelectric properties of InSb: Studies on In/Ga doped GaSb/InSb crystals
摘要： In/Ga elements were doped in GaSb/InSb crystals respectively, and their thermoelectric performances were studied. The crystals had cubic zinc blende structure with change in lattice parameters. The charge transfer occurred between all the three (In, Ga and Sb) elements when In was doped with GaSb. Whereas in Ga doped InSb crystals, the charge transfer occurred only among Ga and Sb elements. In/Ga doped GaSb/InSb crystals exhibited degenerate and non-degenerate electrical properties, respectively. Optical modes of phonon vibrations were present, and their transverse mode was dominant over longitudinal mode in all the samples. The thermoelectric ?gure of merit (ZT) of In doped GaSb crystals were low because of their low power factor and high thermal conductivity. The highest power factor (59.5 μW/cmK2) and ZT (0.56) at 573 K were achieved by Ga doped (1 × 1021/cm3) InSb crystal. The ZT 0.56 at 573 K is thus far the highest among other reported values of InSb crystals.
关键词： D. Point defect,B. Thermoelectric properties,A. Intermetallics,C. Crystal growth,G. Thermoelectric power generation
更新于2025-09-10 09:29:36
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Facile Synthesis and Characterization of Crystalline Iron Phthalocyanine
摘要： Iron phthalocyanine (FePc) has been successfully synthesized by a solvothermal method using 1, 8-Diazabicyclo [5.4.0] undec-7-ene as the catalyst. The crystal structure and the morphology of FePc powder were systematically characterized by X-ray diffraction, Fourier transform infrared spectrometer, ultraviolet-visible absorption spectra and field emission scanning electron microscopy with energy-dispersive spectrometer, respectively. The FePc with a pure β phase is observed with a large yield up to 80%. It shows a rod-like shape in the microstructure. The length is in the range of 200–600 μm and the width is of 5-20 μm. The present FePc could have potential applications for micro-electronic devices.
关键词： Semiconductors,Crystal growth,Electronic materials
更新于2025-09-09 09:28:46
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Infrared Investigations of the Neutral-Ionic Phase Transition in TTF-CA and Its Dynamics
摘要： The neutral-ionic phase transition in TTF-CA was investigated by steady-state and time-resolved infrared spectroscopy. We describe the growth of high-quality single crystals and their characterization. Extended theoretical calculations were performed in order to obtain the band structure, the molecular vibrational modes and the optical spectra along all crystallographic axes. The theoretical results are compared to polarization-dependent infrared reflection experiments. The temperature-dependent optical conductivity is discussed in detail. We study the photo-induced phase transition in the vicinity of thermally-induced neutral-ionic transition. The observed temporal dynamics of the photo-induced states is attributed to the random-walk of neutral-ionic domain walls. We simulate the random-walk annihilation process of domain walls on a one-dimensional chain.
关键词： domain-wall motion,neutral-ionic phase transition,steady-state and transient infrared spectroscopy,TTF-CA,charge-transfer salts,characterization,random-walk simulations,light-induced phase transition,vibrational spectroscopy,crystal growth
更新于2025-09-09 09:28:46
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Linear and Third Order Non-Linear Optical Properties of Urea Salicylic Acid Crystal
摘要： An organic non-linear optical crystal urea salicylic acid was grown by slow evaporation method using the mixed solvent of ethanol and water in equal ratio. The lattice parameters of urea salicylic acid crystal were obtained by single X-ray diffraction study. The optical transmittance study revealed the good transmission window of the urea-salicylic acid and its suitability for optical applications. The non-linear refractive index, n2, absorption coefficient, β and third order susceptibility, χ(3) have been measured through the Z-scan technique with He-Ne laser at 632.8 nm. The grown urea salicylic acid crystal exhibits two photon absorption and self-defocussing performance.
关键词： Crystal growth,X-ray diffraction,Optical properties
更新于2025-09-09 09:28:46