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Luminescence properties in relation to controllable morphologies of Ba <sub/>3</sub> [Ge <sub/>2</sub> B <sub/>7</sub> O <sub/>16</sub> (OH) <sub/>2</sub> ](OH)(H <sub/>2</sub> O):Eu <sup>3+</sup> and its thermal conversion product Ba <sub/>3</sub> Ge <sub/>2</sub> B <sub/>6</sub> O <sub/>16</sub> :Eu <sup>3+</sup>
摘要： Luminescence properties in relation to controllable morphologies of Ba3[Ge2B7O16(OH)2](OH)(H2O):Eu3+ and its thermal conversion product Ba3Ge2B6O16:Eu3+ were investigated. Three types of morphologies of Eu3+-doped Ba3[Ge2B7O16(OH)2](OH)(H2O) phosphors were obtained via hydrothermal reactions by different kinds of raw materials. In addition, Ba3Ge2B6O16:Eu3+ phosphors were obtained by calcining the precursor Ba3[Ge2B7O16(OH)2](OH)(H2O):Eu3+. The structure and morphology of the obtained samples were characterized by XRD, EDS, FT-IR, TG-DTA, SEM and HRTEM. Herein, the effects of the synthesis parameters, including the reaction temperature, boron sources and the dosage, doping of rare earth on the photoluminescence (PL) properties of Ba3[Ge2B7O16(OH)2](OH)(H2O) were investigated in detail. The lifetime and absolute quantum yield (QY) of different morphologies of Ba3[Ge2B7O16(OH)2](OH)(H2O):Eu3+ were also measured. The PL properties of the Ba3Ge2B6O16:Eu3+ phosphor prepared by the precursor calcination method compared with those prepared by the high-temperature solid-state method are discussed.
关键词： Morphologies,Eu3+ doping,Hydrothermal,Borogermanates,Phosphors,Luminescence
更新于2025-11-14 17:04:02
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Synthesis, characterization, optical and electrochemical band gaps of green poly(azomethine-ester)s containing oxalyl and succinyl units
摘要： A new series of poly(azomethine-ester)s (PAZ-E)s with different (turning ortho, meta and para) positions were synthesized by condensation polymerization. The chemical structure of polymers was veri?ed by 1H-NMR, 13C-NMR, FTIR and UV–Vis measurements. Electrochemical characteristics of the corresponding polymers were obtained with cyclic voltammetric (CV) analysis. Thermal characteristics of the obtained polymers were analysed by TG-DTA, DMA and DSC measurements. The ?rst degradation temperature values of PAZ-E compounds were found between 198 and 250?C from TGA measurements. Photophysical characteristics of the obtained polymers were explained with photoluminescence (PL) spectroscopy. Molecular weight distributions of (PAZ-E)s were obtained by gel permeation chromatographic (GPC) analysis. Two- and three-dimensional (2D and 3D) properties and images of the synthesized (PAZ-E)s were analysed by SEM and AFM surface analysis techniques, respectively. Electrochemical band gap (E g) values of (PAZ-E)s P-9, P-10, P-11, P-12, P-13 and P-14 were calculated as 2.58, 2.14, 1.90, 2.06, 1.89 and 1.69 eV, respectively. The E g values of the (PAZ-E)s were found to be quite low.
关键词： surface morphologies,Poly(azomethine-ester),electrochemical properties,photophysical behaviour,schiff base,thermal degradation
更新于2025-11-14 15:26:12
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Growth of perovskite nanocrystals in poly-tetra fluoroethylene based microsystem: On-line and off-line measurements
摘要： Cesium lead halide perovskite nanocrystals are photoelectric nanomaterials that have potential applications in a variety of areas due to their excellent photoelectric and tunable photo luminescent properties. In this work, we investigate the synergetic effects of reaction temperature, reaction-capillary length and flow rate on the growth kinetics of perovskite nanocrystals in PTFE-based microsystem and the photoluminescence characteristics of the synthesized nanocrystals both online and offline. The on-line measurement finds that increasing the reaction temperature leads to the increase of the wavelength of the PL emission peak of the nanocrystals synthesized at different reaction temperatures decreases with the increase of the flow rate. The off-line measurement reveals that increasing the flow rate generally leads to the blueshift of the PL emission peaks and the decrease of the average size of the perovskite nanocrystals synthesized at the reaction temperature of 160 oC in the capillary length of 60 cm. Increasing temperature leads to the increase of the emission wavelength of the perovskite nanocrystals from 560 nm to 608 nm. The temperature dependence of the average size of the synthesized nanocrystals with the same synthesis conditions at different temperatures can be described by the Arrhenius relationship with an activation energy of 8.54 kJ/mol. Five different cross-sections of the synthesized perovskite nanocrystals are observed, including rhombus, hexagon, rectangle, square and quadrangle with three of them being observed for the first time.
关键词： microreaction system,morphologies,growth kinetics,reaction parameters,perovskite nanocrystal
更新于2025-09-23 15:23:52
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A sola??gel synthesis to prepare size and shape-controlled mesoporous nanostructures of binary (IIa??VI) metal oxides
摘要： A base-catalyzed sol–gel approach combined with a solvent-driven self-assembly process at low temperature is augmented to make manganese oxide (Mn3O4), copper oxide (CuO), and magnesium hydroxide (Mg(OH)2) nanostructures with size- and shape-controlled morphologies. Nanostructures of Mn3O4 with either hexagonal, irregular particle, or ribbon shape morphologies with an average diameter ranged from 100 to 200 nm have been prepared in four di?erent solvent types. In all morphologies of Mn3O4, the experimental XRD patterns have indexed the nanocrystal unit cell structure to triclinic. The hexagonal nanoparticles of Mn3O4 exhibit high mesoporocity with a BET surface area of 91.68 m2 g?1 and BJH desorption average pore diameter of ～28 nm. In the preparation of CuO nanostructures, highly nanoporous thin sheets have been produced in water and water/toluene solvent systems. The simulated XRD pattern matches the experimental XRD patterns of CuO nanostructures and indexes the nanocrystal unit cell structure to monoclinic. With the smallest desorption total pore volume of 0.09 cm3 g?1, CuO nanosheets have yielded the lowest BET surface area of 18.31 m2 g?1 and a BHJ desorption average pore diameter of ～16 nm. The sol of magnesium hydroxide nanocrystals produces highly nanoporous hexagonal nanoplates in water and water/toluene solvent systems. The wide angle powder XRD patterns show well-de?ned Bragg's peaks, indexing to a hexagonal unit cell structure. The hexagonal plates show a signi?cantly high BET surface area (72.31 m2 g?1), which is slightly lower than the surface area of Mn3O4 hexagonal nanoparticles. The non-template driven sol–gel synthesis process demonstrated herein provides a facile method to prepare highly mesoporous and nanoporous nanostructures of binary (II–VI) metal oxides and their hydroxide derivatives, enabling potential nanostructure platforms with high activities and selectivities for catalysis applications.
关键词： catalysis applications,size and shape-controlled morphologies,mesoporous nanostructures,binary (II–VI) metal oxides,sol–gel synthesis
更新于2025-09-23 15:19:57
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Study on the morphologies and electro-optical properties of cyano-phenyl-ester liquid crystals/polymer composite films prepared by a stepwise polymerisation
摘要： In this work, a series of liquid crystal molecules containing cyano-phenyl-ester was designed and synthesised. Subsequently, a novel cyano-phenyl-ester liquid crystals (CPE-LCs) with a wide temperature range from ?30°C to 96.4°C were developed by mixturing these liquid crystal compositions. Then as the host materials, the CPE-LCs were used for preparing polymer-dispersed and polymer-stabilised cholesteric liquid crystals (PD&SCLC) composite ?lms by a stepwise polymerisation. The morphologies and electro-optical properties of the as-made composite ?lms were systematically investigated through varying the acrylate liquid crystalline polymerisable monomers content, chiral doping R1011 content, applied electric ?eld intensity and polymerisation time. Indeed, the formation of homeotropically aligned anisotropic polymer networks (HAAPNs) enabled to reduce the driving voltage of PD&SCLC from 86.6 V to 22.2 V with a reasonable contrast ratio. This work provides a new method to optimise PD&SCLC composite ?lms in terms of the host liquid crystals.
关键词： electro-optical properties,polymer-dispersed and polymer-stabilised cholesteric liquid crystals,network morphologies,Cyano-phenyl-ester liquid crystals,stepwise polymerisation
更新于2025-09-23 15:19:57
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Understanding of Imine Substitution in Wide Bandgap Polymer Donor–Induced Efficiency Enhancement in All-Polymer Solar Cells
摘要： All-polymer solar cells (all-PSCs) are proven to possess outstanding thermal and mechanical stabilities. However, concurrently achieving appropriate phase-separated pattern, efficient charge transportation, and adequate charge transfer between donor and acceptor components is still a challenge, and thus, only a few polymer-polymer BHJ blends have yielded BHJ device PCEs >8%. Generally, polymer backbone substitutions may have a direct influence on the device performance. Thus, this report examines a set of wide bandgap polymer donor analogues composed of thienothiophene (TT) or thiazolothiazole (TTz) motif, and their all-PSC device performance with N2200. Results show that all-PSCs based on the imine-substituted derivative PBDT-TTz exhibit power conversion efficiencies (PCE) as high as 8.4%, which largely outperform the analogue PBDT-TT-based ones with PCEs of only 0.7%. This work reveals that the imine substitution in polymer backbones of PBDT-TTz not only increases the ionization potential (IP) and electron affinity (EA), narrows the optical gap (Eopt), but also has significantly impacts on the BHJ film morphologies. PBDT-TTz:N2200 BHJ blends present better miscibility, suppressed phase separation, much stronger crystallinity, and face-on ordering, which are contributed to efficient exciton dissociation, charge transportation, and therefore, high-efficiency in all-PSCs. This study demonstrates that the imine-substituted polymers composed of TTz motif, which can be easily synthesized through a facile two-step procedure, are a promising class of wide bandgap polymer donors for efficient all-PSCs.
关键词： Imine substitution,All-polymer solar cells,Thiazolothiazole,Wide bandgap polymer donors,BHJ film morphologies
更新于2025-09-12 10:27:22
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The preparation and photocatalytic performance research of CdSe and wool ball-like GO/CdSe microspheres
摘要： Different morphologies of CdSe and GO (graphene oxide)/CdSe microspheres like wool ball and walnut shape have been made through hydrothermal method using CTAB as surfactant. X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), X-ray energy dispersive spectrometer (EDS), scanning electron microscope (SEM), Raman spectra, and UVevis absorption spectrum, were used to intensively investigate the structures, morphologies, chemical compositions and optical properties of CdSe and GO/CdSe microspheres. The results of XRD revealed that GO/CdSe microspheres have lead-zinc mineral structure. The results of XRD, EDS, XPS and Raman spectra showed that GO/CdSe microspheres were grown on GO sheets. Also UVevis absorption spectrum indicated that GO/CdSe microspheres enhanced absorbance in UV light region and visible light region. Through comparative experiments, the results showed that pH ? 4 is the optimal pH value for degrading Rhodamine B (RhB) solution. To study the photocatalytic performance of GO/CdSe microspheres, we catalyzed the degradation of RhB aqueous solution irradiated by visible light. The photocatalytic results showed that the wool ball-like GO/CdSe microspheres exhibited better photocatalytic activity than rough CdSe.
关键词： GO/CdSe microspheres,Hydrothermal method,Morphologies,GO,Photocatalytic activity
更新于2025-09-10 09:29:36
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Facile synthesis of Cu2O particles with different morphologies
摘要： Cu2O particles with cubic, octahedral, truncated octahedral and cubic truncated morphologies were synthesized using a simple chemical reduction method at room temperature. The nanocrystals were synthesized directly in aqueous solution by varying the molar concentration of CuCl2 precursor salt added to the sodium borohydride NaBH4 as a reducing agent. The solids obtained were characterized by ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). UV-vis absorption spectra exhibit peaks with characteristic wavelengths of Cu2O. SEM and TEM reveal particles with a cubic morphology at 15 mM CuCl2, with an average particle size of 100 nm. Cu2O particles are also grown in an octahedral shape at 16 mM of CuCl2, having an average particle size of 150 nm. Finally, truncated octahedral and truncated cubic forms were produced for concentrations in the range of 17 to 20 mM with 100 nm of average size.
关键词： Electron microscopy,Chemical-reduction synthesis,Sodium borohydride,Different-shape morphologies,Cooper oxide
更新于2025-09-09 09:28:46
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Pattern recognition of messily grown nanowire morphologies applying multi-layer connected self-organized feature maps
摘要： Multi-layer connected self-organizing feature maps (SOFMs) and the associated learning procedure were proposed to achieve efficient recognition and clustering of messily grown nanowire morphologies. The network is made up by several paratactic 2-D SOFMs with inter-layer connections. By means of Monte Carlo simulations, virtual morphologies were generated to be the training samples. With the unsupervised inner-layer and inter-layer learning, the neural network can cluster different morphologies of messily grown nanowires and build connections between the morphological microstructure and geometrical features of nanowires within. Then, the as-proposed networks were applied on recognitions and quantitative estimations of the experimental morphologies. Results show that the as-trained SOFMs are able to cluster the morphologies and recognize the average length and quantity of the messily grown nanowires within. The inter-layer connections between winning neurons on each competitive layer have significant influence on the relations between the microstructure of the morphology and physical parameters of the nanowires within.
关键词： Messily grown nanowire morphologies,Artificial neural networks,Monte Carlo simulation,Pattern recognition,Self-organizing feature maps
更新于2025-09-09 09:28:46
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Synthesis and characterization of morphology-controllable BiFeO3 particles with efficient photocatalytic activity
摘要： The single phase BiFeO3 (BFO) particles were synthetised by a facile hydrothermal method under the special sodium hydroxide (NaOH) concentration. The particles have been systematically characterized by X-ray diffraction technique, ?eld emission scanning electron microscopy, energy dispersive spectrometer, fourier transform infrared spectroscopy and UV–vis spectra. It is found that a wide range of NaOH concentration of 1–3 M could induce a high crystalline quality of BFO. Interestingly, it is noted that di?erent NaOH concentrations have a signi?cant e?ect on the morphology of BFO particles. With the increase of NaOH concentration, the morphology changes from alveolate BFO to cubic BFO particles. Moreover, the light absorption characteristics and the band gap of BFO particles are strongly dependent on their morphology. This result in the di?erence of photocatalytic degradation ability of alveolate BFO particles compared to that of cubic BFO particles.
关键词： Photocatalytic activity,Hydrothermal,Morphologies,BiFeO3
更新于2025-09-04 15:30:14