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Structural characterization of bulk and nanoparticle lead halide perovskite thin films by (S)TEM techniques
摘要： Lead halide (APbX3) perovskites, in polycrystalline thin films but also perovskite nanoparticles (NPs) have demonstrated excellent performances to implement a new generation of photovoltaic and photonic devices. The structural characterization of APbX3 thin films using (scanning) transmission electron microscopy ((S)TEM) techniques can provide valuable information that can be used to understand and model their optoelectronic performance and device properties. However, since APbX3 perovskites are soft materials, their characterization using (S)TEM is challenging. Here, we study and compare the structural properties of two different metal halide APbX3 perovskite thin films: bulk CH3NH3PbI3 prepared by spin-coating of the precursors in solution and CsPbBr3 colloidal NPs synthetized and deposited by doctor blading. Both specimen preparation methods and working conditions for analysis by (S)TEM are properly optimized. We show that CH3NH3PbI3 thin films grown by a one-step method results in the formation of tetragonal perovskite thin films with good adherence to an underlying TiO2 layer, which is characterized by a photoluminescence (PL) emission band centered at 775 nm. The perovskite thin films based on CsPbBr3 colloidal NPs, which are used as the building blocks of the film, they are preserved by the deposition process, even if small gaps are observed between adjacent NPs. The crystal structure of CsPbBr3 NPs is cubic, which is beneficial for optical properties due to its optimal band gap. The absorption and PL spectra measured in both the thin film and the colloidal solution of CsPbBr3 NPs are very similar, indicating a good homogeneity of the thin films and the absence of aggregation of NPs. However, a particular care was required to avoid long electron irradiation times during our structural studies, even at a low voltage of 80 kV, as the material was observed to decompose through Pb segregation.
关键词： structural characterization,TEM,thin films,optoelectronics,STEM,nanoparticles,perovskite
更新于2025-09-23 15:23:52
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Structural characterization of Nd-Fe <sub/>3</sub> O <sub/>4</sub> nanoparticles prepared by hydrothermal synthesis method
摘要： Magnetic nanoparticles of Nd-Fe3O4 were prepared by hydrothermal synthesis method, using NdCl3·6H2O and FeCl3·6H2O as the starting materials in this paper. The structure and morphology of nanoparticles were investigated by XRD, FTIR, EDS and TEM. The results showed that, while the addition of Nd at 10% in mole ratio, resulted in the formation of Nd2O3 crystal peak in cubic Fe3O4 nanocrystallites by XRD. The absorption bands of Fe–O, –OH, –O–C–O– and –CH2– were accordant to the correspondent chemical groups by FTIR. The morphology of the prepared nanoparticles exhibited spherical structure and evenly distributed without agglomeration phenomenon by TEM. The elemental composition were mainly consistent with the precursor materials used in the experiment.
关键词： magnetic nanoparticles,hydrothermal synthesis,Nd-Fe3O4,Structural characterization
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Structural characterization and emission properties of phosphorus-doped NCD films
摘要： Phosphorus-doped NCD films were grown on n-type silicon substrate by plasma-enhanced CVD with H2, CH4, and PH3 gas mixture for cold cathode application. The structure properties were characterized by Raman spectroscopy with a green laser of 532 nm at room temperature, scanning electron microscope, transmission electron microscope, and electron energy-less spectroscopy. Grown films show a good conductivity and have a typical structure with a combination of sp3 diamond gains with size around 20-100 nm and sp2 grain boundaries. The electron emission properties were characterized as comparing with single crystal, NCD film, and tip-array NCD. The tip-array NCD shows good emission properties with lower threshold electric filed and higher saturation current.
关键词： Structural characterization,Nano crystal diamond (NCD),PECVD,electron emitter,Phosphorus doping
更新于2025-09-23 15:21:21
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[Springer Theses] Electrical Properties of Indium Arsenide Nanowires and Their Field-Effect Transistors || Fabrication, Characterization and Parameter?Extraction of InAs Nanowire-Based Device
摘要： Nanofabrication, low noise electrical measurement and various nanoscale characterization methods are frequently used in the study. This chapter will give as introduction on the growth method, fabrication techniques, characterization methods of materials and devices, measurement systems, and way to extract the electrical parameters of InAs nanowires FET devices.
关键词： Parameter extraction,Fabrication of nanowire devices,Electrical measurement,Structural characterization
更新于2025-09-23 15:21:21
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Polymeric iodobismuthates {[Bi <sub/>3</sub> I <sub/>10</sub> ]} and {[BiI <sub/>4</sub> ]} with N-heterocyclic cations: promising perovskite-like photoactive materials for electronic devices
摘要： A screening of the reactions between BiI3 and iodide salts of different N-alkylated heterocycles (pyridine, quinoline, isoquinoline) resulted in the preparation and structural characterization of six novel iodobismuthate complexes, including two compounds exhibiting an unprecedented {[Bi3I10]} polymeric moiety. It has been shown that the chemical composition and structure of the iodobismuthates significantly affect their optical and electronic properties. The narrowest band gaps (Eg) were revealed by {[Bi3I10]} iodobismuthates, while the compounds incorporating {[BiI4]} polymeric frameworks showed 0.2–0.3 eV wider Eg. GIXRD analysis evidenced that all three iodobismuthates investigated in thin films show mainly the horizontal (parallel to the substrate) orientation of the 1D polymeric Bi–I frameworks. Such arrangement blocks the charge transport in vertical direction (orthogonal to the substrate) since the conductive Bi–I chains are separated with insulating bulky organic cations. As a consequence, standard planar junction solar cells based on new iodobismuthates revealed low power conversion efficiencies approaching 0.12% only. However, strong in-plane photoconductivity observed for iodobismuthates enabled the fabrication of efficient planar photodetectors, which paves a way to the practical use of this exotic family of materials. Most importantly, the presented systematic study revealed the most general guidelines for future rational design of perovskite-like materials for emerging generation of environment-friendly perovskite photovoltaics emphasizing the importance of the isotropic charge transport in the films of 3D materials and achieving proper orientation of 1D and 2D frameworks with respect to the charge collecting electrodes in anisotropic low dimensional systems.
关键词： photodetectors,perovskite-like materials,iodobismuthates,structural characterization,charge transport,photovoltaics
更新于2025-09-19 17:15:36
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Structural characterization of Argania spinosa Moroccan wooden artifacts during natural degradation progress using infrared spectroscopy (ATR-FTIR) and X-Ray diffraction (XRD)
摘要： The present work is focused on spectroscopic study of four samples of Argan wooden artifact pertaining to the 17th, 18th, 20th and 21st centuries. The objective is to characterize their unknown structures by the study of their non degraded parts and to investigate changes occurred in their degraded parts due to the natural degradation process. Attenuated total re?ectance Fourier transform infrared spectroscopy gauges the presence of many functional groups related to cellulose I and/or II (OH, C–O–C and –CH2), hemicelluloses (particularly C?O (cid:2)1), and lignin (OH phenolic, Car-O and C?Car) and provides qualitative information on the state of wood alteration by informing on the evolution of new former C?O bands. The degree of conversion to carbonyl group, especially quinone or p-quinone at 1650 cm (cid:2)1, is correlated to lignin degradation, while the absence of the C?O acetoxy absorption is ascribable to occurred deterioration in hemicelluloses, and (cid:2)1. X-ray diffraction determines the presence of two forms of cellulose; amorphous cellulose at 18.5(cid:3) 2θ and predominant crystalline cellulose Iβ at 2θ ? 22.6(cid:3) which characterized by an intense peak. The decrease of crystallinity index values con?rms the deterioration level and obvious changes in crystallinity level. However, the microcrystalline structure appears unaltered because no signi?cant changes were observed for calculated cristallite seize. The obtained results depend on the prolonged time of ageing, natural deterioration phenomena, and wood part (internal or external) that is exposed to degradation. The combination of these two methods is useful for an accurate estimation of the degradation level of argan wood.
关键词： Chemistry,Argan wood artifact,XRD,Analytical chemistry,Natural product chemistry,Materials Chemistry,Natural degradation,Archaeology,ATR-FTIR spectroscopy,Crystallinity,Lignocelluloses,Structural characterization,Materials Science,Organic chemistry
更新于2025-09-12 10:27:22
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Young’s double-slit interference enabled by surface plasmon polaritons: a review
摘要： Red yeast rice has been utilized for colouring food, brewing wine and preserving meat, which is also used as a folk medicine for centuries. In this study, a water-soluble non-starch polysaccharide from red yeast rice (RYRP) was extracted by using ultrasonic-assisted extraction method. By using Box–Behnken design (BBD) to optimize the parameters for extracting the RYRP, the maximum extraction yield (3.37%±0.78%) was obtained under the optimal extraction conditions as follows: ratio of water to raw material (40 mL/g), extraction temperature (62 °C), extraction time (75 min) and ultrasonic power (200 W). Moreover, monosaccharide composition analysis showed that RYRP was consisted of mannose, glucosamine, glucose and galactose with a molar ratio of 0.152:0.015:1:0.149. The molecular weight distribution analysis showed that the average molecular weight of the RYRP fraction was about 3.49 × 103 Da. Furthermore, RYRP exhibited significant antioxidant activities in vitro and the gastrointestinal-protective effect in vivo using gastrointestinal disorders (GD) model mice. RYRP could be explored as a potential source in the pharmaceutical and functional food industries.
关键词： Polysaccharide,Ultrasonic-assisted extraction,Red yeast rice,Antioxidant activities,Structural characterization,Gastrointestinal-protective effect
更新于2025-09-11 14:15:04
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crystals
摘要： Transition-metal dichalcogenides open novel opportunities for the exploration of exciting new physics and devices. As a representative system, 2H -MoS2 has been extensively investigated owing to its unique band structure with a large band gap, degenerate valleys, and nonzero Berry curvature. However, experimental studies of metastable 1T polytypes have been a challenge for a long time, and electronic properties are obscure due to the inaccessibility of single phase without the coexistence of 1T (cid:2), 1T (cid:2)(cid:2), and 1T (cid:2)(cid:2)(cid:2) lattice structures, which hinder the broad applications of MoS2 in future nanodevices and optoelectronic devices. Using Kx (H2O)yMoS2 as the precursor, we have successfully obtained high-quality layered crystals of the metastable 1T (cid:2)(cid:2)(cid:2)-MoS2 with √3a superstructure and metastable 1T (cid:2)-MoS2 with a × 2a superstructure, as evidenced by structural characterizations through scanning tunneling microscopy, Raman spectroscopy, and x-ray diffraction. It is found that the metastable 1T (cid:2)-MoS2 is a superconductor with onset transition temperature (Tc) of 4.2 K, while the metastable 1T (cid:2)(cid:2)(cid:2)-MoS2 shows either superconductivity with Tc of 5.3 K or insulating behavior, which strongly depends on the synthesis procedure. Both of the metastable polytypes of MoS2 crystals can be transformed to the stable 2H phase with mild annealing at about 70 °C in He atmosphere. These ?ndings provide pivotal information on the atomic con?gurations and physical properties of 1T polytypes of MoS2.
关键词： Transition-metal dichalcogenides,MoS2,metastable phases,superconductivity,structural characterization
更新于2025-09-10 09:29:36
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Synthesis and Structural Characterizations of meso-Tetraphenyl Porphyrin
摘要： In this paper, tetraphenyl porphyrin (H2TPP) was synthesized by using pyrrole and benzaldehyde as raw materials under the catalysis of p-nitrobenzoic acid. The prepared tetraphenyl porphyrin was re-crystallized in a mixed system of methanol and methylene chloride (CH2Cl2) and the yield of tetraphenyl porphyrin is 34.2 %. Tetraphenyl porphyrin was characterized by using FTIR, UV-visible, 1H NMR and fluorescence spectrophotometer. The effects on the yield of tetraphenyl porphyrin at different volumes of dimethylbenzene as solvent were explored.
关键词： Recrystallization,Tetraphenylporphyrin,Structural characterization
更新于2025-09-10 09:29:36
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Structural, optical and magnetic properties of nanophase NiWO4 for potential applications
摘要： Nanocrystalline NiWO4 powder samples were synthesized by direct-chemical precipitation method. Thermal stability of the sample was studied by thermo gravimetric and differential thermal analysis. Structural characterization of NiWO4 nanoparticles was done with X-ray diffraction and field emission scanning electron microscopy. Elemental analysis of the samples were done with energy dispersive X-ray spectroscopy. Vibration modes of as prepared samples were analysed using Fourier transform infrared spectroscopy and Raman spectroscopy. Optical properties of the samples were explored using UV-vis spectroscopy and photoluminescence (PL) spectroscopy. Magnetic properties of NiWO4 nanoparticles were analysed using vibrating sample magnetometer (VSM). Effect of calcination temperature on structural, vibrational, optical and magnetic properties of the NiWO4 samples were also investigated. The results obtained from various characterization techniques found that NiWO4 nanoparticle have the potential use in light emitting diodes (LEDs), biomedical and sensing applications.
关键词： NiWO4,thermal stability,optical properties,nanoparticles,magnetic properties,direct-chemical precipitation,structural characterization
更新于2025-09-09 09:28:46