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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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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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Development of Process for Fast Plasma-Chemical Through Etching of Single-Crystal Quartz in SF6/O2 Gas Mixture
摘要： Process for deep plasma-chemical etching of single-crystal quartz plates in a SF6/O2 gas mixture was developed. The method of scienti? c experiment design based on the Taguchi matrix technique was used to rank basic technological parameters (bias voltage applied to the substrate holder, output power of the high-frequency generator, oxygen ? ow rate, and position of the substrate holder relative to the lower edge of the discharge chamber) as regards their in? uence on the etching rate. The ranking results were used to optimize the plasma-chemical etching process and perform a control experiment on through etching of windows with large linear dimensions (3 × 10 mm) in a single-crystal quartz plate (z-cut) with thickness of 369 μm.
关键词： single-crystal quartz,plasma-chemical etching,sulfur hexa? uoride,Taguchi method
更新于2025-09-10 09:29:36
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Organic single-crystal phototransistor with unique wavelength-detection characteristics; 具有独特波长检测特性的有机单晶光电晶体管;
摘要： Organic phototransistors based on high-quality 2,8-dichloro-5,11-dihexyl-indolo[3,2-b]carbazo (CHICZ) single show the highest photoresponsivity of 3×103 A W?1, photosensitivity of 2×104 and the detectivity can achieve 8.4×1014 Jones. We also discovered good linear dependence of log(photosensitivity) versus the wavelength when the devices were illuminated with a series of same-intensity but different-wavelength lights. The organic phototransistors based on CHICZ single crystal have potential applications in wavelength-detection.
关键词： photo-responsivity,photosensitivity,wavelength-detection,organic phototransistor,single crystal
更新于2025-09-10 09:29:36
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In situ Raman spectroscopic evidence for oxygen reduction reaction intermediates at platinum single-crystal surfaces
摘要： Developing an understanding of structure–activity relationships and reaction mechanisms of catalytic processes is critical to the successful design of highly efficient catalysts. As a fundamental reaction in fuel cells, elucidation of the oxygen reduction reaction (ORR) mechanism at Pt(hkl) surfaces has remained a significant challenge for researchers. Here, we employ in situ electrochemical surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) calculation techniques to examine the ORR process at Pt(hkl) surfaces. Direct spectroscopic evidence for ORR intermediates indicates that, under acidic conditions, the pathway of ORR at Pt(111) occurs through the formation of HO2*, whereas at Pt(110) and Pt(100) it occurs via the generation of OH*. However, we propose that the pathway of the ORR under alkaline conditions at Pt(hkl) surfaces mainly occurs through the formation of O2?. Notably, these results demonstrate that the SERS technique offers an effective and reliable way for real-time investigation of catalytic processes at atomically flat surfaces not normally amenable to study with Raman spectroscopy.
关键词： density functional theory,in situ Raman spectroscopy,electrochemical surface-enhanced Raman spectroscopy,oxygen reduction reaction,platinum single-crystal surfaces
更新于2025-09-10 09:29:36
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Effect of the Gamma-Ray Irradiation on the Electric and Optical Properties of SrTiO3 Single Crystals
摘要： We investigated the visible emission property of SrTiO3 (STO) single crystals irradiated with gammy-ray (γ-ray) at various total doses up to 900 kGy. The electric and optical absorption properties of the irradiated STO samples were hardly changed with the γ-ray irradiation, compared with those of un-irradiated STO. In contrast, the visible emission near 550 nm increased with the γ-ray dose increasing. While the development of the visible emission was indicative of the increase of oxygen vacancies inside STO by the γ-ray irradiation, the newly generated oxygen vacancies were not significantly harmful to the electric and optical properties of STO. We concluded that the STO single crystal should have a good tolerance against the damage by the γ-ray irradiation.
关键词： Gamma-ray irradiation,Photoluminescence,Oxygen vacancy,SrTiO3 single crystal
更新于2025-09-10 09:29:36
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Assessing UO2 sample quality with μ-Raman spectroscopy
摘要： m-Raman spectroscopy of UO2 has demonstrated its value as a tool in nuclear forensics and for analyzing nuclear fuels, but its ability to evaluate UO2 sample quality has been relatively unexplored. To investigate this potential, a three-pronged study that uses Raman spectroscopy to analyze 1) three distinct qualities of UO2 single crystals with two different excitation lasers, 2) a high quality single crystal UO2 sample that is progressively damaged with a laser, and 3) a single crystal of UO2 grown on top of a ThO2 substrate was undertaken. The results demonstrate that the peak height ratio between the second order longitudinal optical phonon signal near 1145 cm?1 and the T2g peak located near 450 cm?1 is directly correlated with crystal quality when a 532 nm excitation source is used. Furthermore, this observed pattern relies upon the two most intense peaks that are present in the Raman spectra, making it more robust to lower signal-to-noise ratios than similar trends present in the peak height ratio between the first order longitudinal optical phonon signal near 565 cm?1 and the T2g peak. Both peak height ratios are more sensitive indicators of the crystal quality than the width ratios of the same signals or the associated wavenumber shift in the T2g peak location. The correlation between the 2LO and T2g peak heights and the overall crystal quality offers the potential to directly assess and compare the quality of different samples of single crystal UO2.
关键词： Uranium dioxide,Sample quality,m-Raman spectroscopy,UO2,Single crystal
更新于2025-09-09 09:28:46
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New photochromic indoline spiropyrans containing cationic substituent in the 2H-chromene moiety
摘要： New indoline spiropyrans containing conjugated cationic fragments and bulky substituents in the 2H-chromene moiety were synthesized by a simple one-pot method. The structures of the obtained compounds were confirmed by 1H and 13C NMR (including 2D methods) and IR spectroscopy, as well as by element analysis and HRMS. Molecular structure of 1,3,3-trimethyl-60-formyl-80-benzyl-spiro[indoline-2,20-2H-chromene] was refined by single crystal X-ray. A comparative analysis of the spectral and photochromic properties of salt spiropyrans and similar structures without a cationic fragment was carried out. It was found that the introduction of the cationic substituent at the 60-position of the 2H-chromene moiety leads to a significant increase in the photoinduced isomer's lifetime.
关键词： Indolines,Molecular switches,2H-chromenes,Photochromism,Single crystal X-ray analysis,Spiropyrans
更新于2025-09-09 09:28:46
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Second and third order nonlinear optical studies of a novel thiophene substituted chalcone derivative
摘要： A noncentrosymmetric chalcone derivative (E)-1-(thiophen-2-yl)-3-(3, 4, 5-trimethoxyphenyl) prop-2-en-1-one (TTMP) was synthesized using Claisen Schmidt condensation approach and single crystals were grown using slow evaporation method. The grown TTMP crystals crystallises in orthorhombic structure with Pna21 space group. The intermolecular interactions of the TTMP crystals were envisioned by Hirshfeld surface analysis (HSA). Further, the structural conformations of the crystal were carried out by using 1H NMR, FTIR and FT-Raman spectral analysis. The UV-Vis-NIR spectrum of the sample clearly shows the prime transparency in the entire visible and near infrared region. Thermal studies (TG/DTA/DSC) of the TTMP sample shows excellent thermal stability and phase transition and also noticed that crystal was most stable up to 152.65 0C. The second harmonic generation efficiency was obtained for the crystals using Nd:YAG laser and is to be 1.93 times that of urea . The third order nonlinear absorption coefficient (β), nonlinear refractive index (n2), third-order nonlinear susceptibilities (χ (3)), second order hyper polarizability (γh) and optical limiting thresholds were determined by Z-scan technique using the Diode-Pumped Solid State (DPSS) Continuous Wave (CW) laser. The results suggest that the TTMP molecules are promising materials for optoelectronic device applications.
关键词： Hirshfeld surfaces,Optical limiting,SHG,Z-scan,Single crystal,Chalcones
更新于2025-09-09 09:28:46
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1D Piezoelectric BaTiO3 Polycrystal of Topochemical Mesocrystal Conversion from Layered H2Ti4O9?H2O Single Crystal
摘要： A 1D piezoelectric BaTiO3 (BT) polycrystal with a tetragonal system was controllably prepared using a one-step hydrothermal soft chemical process. A layered H2Ti4O9·H2O (HTO) single crystal was used as the precursor. Interestingly, the obtained polycrystalline BT constructed from oriented BT nanoparticles shows a set of single-crystalline diffraction points, implying that the BT polycrystal is a mesocrystal. The [010] and [001] directions of the obtained mesocrystalline BT correspond to the [001] and [010] directions of the original HTO crystal, respectively, and the [010] direction of the mesocrystalline BT corresponds to the direction along the length of a 1D rod matrix. An in situ topochemical mesocrystal conversion of mesocrystalline BT grown on the HTO substrate occurred not only on the substrate surface but also in the interlayers owing to the unique TiO6 octahedral layers of HTO. In addition, the piezoelectric response of 1D mesocrystal was captured for the first time. The piezoelectric property of BT mesocrystals hinges on its nanostructure. It is a challenge to develop a special process to prepare highly 1D anisotropic perovskite titanate polycrystals with high crystallinity and piezoelectric response. This novel strategy can be utilized to develop piezoelectric mesocrystalline materials.
关键词： layered H2Ti4O9·H2O single crystal,1D piezoelectric BaTiO3,piezoelectric response,hydrothermal soft chemical process,topochemical mesocrystal conversion
更新于2025-09-09 09:28:46