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Ultra-Rapid Crystallization of L-Alanine Using Monomode Microwaves, Indium Tin Oxide and Metal-Assisted and Microwave-Accelerated Evaporative Crystallization
摘要： The use of indium tin oxide (ITO) and focused monomode microwave heating for the ultra-rapid crystallization of L-alanine (a model amino acid) is reported. Commercially available ITO dots (< 5 mm) attached to blank poly(methyl)methacrylate (PMMA, 5 cm in diameter with 21-well silicon isolators: referred to as the iCrystal plates) were found to withstand prolonged microwave heating during crystallization experiments. Crystallization of L-alanine was performed at room temperature (a control experiment), with the use of two microwave sources: a 2.45 GHz conventional microwave (900 W, power level 1, a control experiment) and 8 GHz (20 W) solid state, monomode microwave source with an applicator tip that focuses the microwave field to a 5-mm cavity. Initial appearance of L-alanine crystals and on iCrystal plates with ITO dots took 47 ± 2.9 min, 12 ± 7.6 min and 1.5 ± 0.5 min at room temperature, using a conventional microwave and focused monomode microwave heating, respectively. Complete evaporation of the solvent using the focused microwaves was achieved in 3.2 ± 0.5 min, which is ~52-fold and ~172-fold faster than that observed at room temperature and using conventional microwave heating, respectively. The size and number of L-alanine crystals was dependent on the type of the 21-well iCrystal plates and the microwave heating method: 33 crystals of 585 ± 137 μm in size at room temperature > 37 crystals of 542 ± 100 μm in size with conventional microwave heating > 331 crystals of 311 ± 190 μm in size with focused monomode microwave. FTIR, optical microscopy and powder X-ray diffraction analysis showed that the chemical composition and crystallinity of the L-alanine crystals did not change when exposed to microwave heating and ITO surfaces. In addition, theoretical simulations for the binding of L-alanine molecules to ITO and other metals showed the predicted nature of hydrogen bonds formed between L-alanine and these surfaces.
关键词： ITO,Microwave heating,Silver island films,Evaporative crystallization
更新于2025-09-23 15:22:29
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The Effects of the Content of NiO on the Microstructure and Photocatalytic Activity of the NiO/TiO2 Composite Film
摘要： The NiO/TiO2 composite films with the NiO content of 3 %, 5 %, 10 %, 13 %, 15 % and 20 % were prepared by mechanical coating technology and subsequent oxidation process. The composition and microstructure of the films were analyzed by X-ray Diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS). The photocatalytic activity was evaluated and the effects of the content of NiO on microstructure and photocatalytic activity of the films were studied. The results show that NiO particles are dispersed in the Ti coatings, and the NiO concentration in the inner layer of the coatings is higher than in the outer layer. With the addition of NiO in the NiO/Ti coating, the ductility is deteriorated and the thickness is reduced of the NiO/Ti coatings. The films with NiO/TiO2/Ti composite microstructure are obtained by the oxidation of NiO/Ti coatings. Photocatalytic efficiency of the films is obviously enhanced with the help of the p-n junction heterostructure in the NiO/TiO2 films. The optimum content of NiO is about 13 %, and the degradation rate of methyl orange solution reaches the maximum value of 88.44 %.
关键词： mechanical coating technology,NiO content,photocatalytic activity,NiO/TiO2 composite films
更新于2025-09-23 15:22:29
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High dielectric and breakdown properties achieved in ternary BaTiO3/MXene/PVDF nanocomposites with low-concentration fillers from enhanced interface polarization
摘要： Although high permittivity is achieved in barium titanate (BT) filled polymer nanocomposites, severely reduced insulation and breakdown properties are frequently found due to overload and agglomeration of BT nanoparticles with ultrahigh specific area. To simultaneously realize high permittivity and breakdown strength, in this work, unfunctionalized 2D Ti3C2 MXene nanosheets with 2 wt % weight concentration were introduced to prepare ternary BT/MXene/polymer nanocomposites by solution cast process. Employing low-concentration conductive MXene instead of high-concentration ferroelectric BT could lead to significant improvement of permittivity of ternary composites, ascribed to remarkably increased interface types and enhanced interface polarization. In comparison to binary BT/polymer composites, ternary composites could have slightly improved dielectric loss and conductivity as well as gracefully reduced breakdown strength, attributed to finely retained high interface compatibility and filler dispersion. Ternary composite containing 8 wt % BT and 2 wt % MXene had a permittivity of 77, loss of 0.15 at 100 Hz and breakdown strength of 220 MV m-1. This work might open the door to large-scale fabrication of promising composites with high permittivity and breakdown strength under low filler loading (~ 10 wt %).
关键词： B. Composites,A. Films,C. Dielectric properties,D. Carbides
更新于2025-09-23 15:22:29
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Influence of annealing temperature on photoluminescence of CePO4 thin films on silicon substrates prepared by electron beam evaporation
摘要： Nanostructured CePO4 thin films were prepared on silicon substrates by electron beam evaporation technique. In this work, the effects of annealing temperature on photoluminescence (PL) of CePO4 thin films were investigated. CePO4 thin films were annealed at different temperatures between 700 and 1100 °C for 30 min in nitrogen. The annealed CePO4 films show a strong ultraviolet emission at room temperature. Besides, a violet/blue emission was observed when the annealing temperature reached 1000 °C. The X-ray diffraction results show the monoclinic structure of CePO4 thin films. The scanning electron microscopy images were taken to confirm different crystallinities. The concentration of different elements was determined by energy-dispersive X-ray spectroscopy. The excellent PL emission in the annealed films indicates that the CePO4 thin films could be useful for silicon-based light sources.
关键词： Annealing,CePO4,Thin films,Photoluminescence
更新于2025-09-23 15:22:29
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Effects of LNO buffer layers on electrical properties of BFO-PT thin films on stainless steel substrates
摘要： Ferroelectric 0.7BiFeO3-0.3PbTiO3 (BFO-PT) thin films were deposited on LaNiO3 (LNO) coated stainless steel (SS) substrates by the sol-gel method. XRD results indicate that both LNO and BFO-PT thin films have the perovskite structure and the film crystallinity is improved with increasing the LNO thickness. The dielectric loss of BFO-PT thin films is reduced significantly with addition of LNO buffer layers, achieving about 4 % at the frequency of 1 kHz, much lower than that of > 20 % for BFO-PT thin films directly deposited on SS substrates. BFO-PT thin films reveal the strong ferroelectricity with remnant polarization (Pr) of about 35 m C/cm2 for LNO of 390 nm. Moreover, addition of LNO buffer layers mitigates the polarization deterioration after the 1.33×108 switching cycles resulting in the improved anti-fatigue properties of BFO-PT thin films. Our results indicate that BFO-PT/LNO multilayer thin films on SS substrates maintain excellent dielectric and ferroelectric properties.
关键词： 0.7BiFeO3-0.3PbTiO3 thin films,Stainless steel substrates,LaNiO3
更新于2025-09-23 15:22:29
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Piezoelectric properties of a near strain-free lead zirconate titanate thin films deposited on a Si substrate
摘要： Chemical solution deposition (CSD)-derived near strain-free lead zirconate titanate (PZT) thin films on a Si substrate were prepared by designing a buffer layer structure. Strain-free PZT thin films with different compositions ranging from Zr/Ti = 50/50 to 58/42 were obtained to demonstrate lattice strain effects on piezoelectric properties. Results show that a near strain-free condition was attained with a SrRuO3 (SRO: 160 nm)/(La0.5,Sr0.5)CoO3 (LSCO: 90 nm)/LaNiO3 (LNO: 120 nm)/stacking structure, even on a Si substrate. The highest effective d33 value of the near strain-free PZT thin film was observed at 53/47 composition, which is the same as bulk materials, although the highest effective d33 value was obtained from 58/42 composition under the compressive lattice strain condition.
关键词： Chemical solution deposition,Piezoelectricity,Thin films,Multilayer structure,Lattice strain,Sol-gel preparation
更新于2025-09-23 15:22:29
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Enhanced electron field emission from nanocrystalline orthorhombic boron nitride films
摘要： Nanocrystalline orthorhombic boron nitride (oBN) thin films with an island-in-honeycomb morphology were prepared on graphite substrate by radio frequency (r.f.) magnetron sputtering. The Field emission (FE) measurement results indicated that the FE properties are significantly enhanced in oBN films compared to high quality cBN films, the turn-on electric field of oBN films is decreased from 17.0 V/μm to 6 V/μm, and the highest emission current density is increased from 2.8 × 10?? to 3 × 10?? A/cm2. The enhanced FE properties of the oBN films can be attributed to significant reduction in effective potential barrier caused by both protruded island-in-honeycomb morphology and honeycomb-like interconnected internal structure.
关键词： Semiconductors,Thin films,Electron field emission,Boron nitride,Physical vapour deposition
更新于2025-09-23 15:22:29
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Contact Angle Relaxation and Long-lasting Hydrophilicity of Sputtered Anatase TiO <sub/>2</sub> Thin Films by Novel Quantitative XPS Analysis
摘要： The contact angle relaxation of TiO2 surfaces is an important problem that must be understood, particularly for long-lasting hydrophilicity under dark conditions. The relaxation of sputtered anatase TiO2 thin films over a long time (~22 days) in an atmospheric environment was observed using quantitative XPS analysis. A new peak was identified as H2O within a donor-acceptor complex at ~2.57 eV above the lattice oxygen peak. This donor?acceptor complex turns out to be a key factor for long lasting hydrophilicity, and our model is presented. Adventitious carbon contamination was not the main cause of the contact angle relaxation. Instead, samples with lower amounts of donor?acceptor complexes (IDAC/Ibulk ≤ ~5%) underwent contact angle relaxation over time, and samples with a high density of donor?acceptor complexes (IDAC/Ibulk ≥ ~10%) showed good hydrophilicity (contact angle ≤ 20°) over 22 days. Larger amounts of basic Ti?OH relative to acidic OHbridge (ITi?OH/Ibridge ≥ 1) resulted in greater amounts of donor?acceptor complexes (IDAC/Ibulk ≥ ~10%). Thus, basic Ti?OH groups interact with H2O by forming a strong electrostatic donor?acceptor complex, leading to long-lasting hydrophilicity. Indeed, TiO2 was transformed to show long lasting hydrophilicity by high-density oxygen plasma treatment by forming sufficient Ti?OH groups and H2O molecules in the donor?acceptor complexes. Contact angle relaxation is closely related to the interactions between water molecules and the TiO2 surface in the dark. It is suggested that the relaxation depends on the number of electrostatic donor?acceptor complexes. This study provides new insight by linking theoretical studies with the experimental contact angle at the TiO2 surface in an ambient environment and is the first study that provides the presented relaxation mechanism.
关键词： Hydrophilicity,Sputtering,Plasma treatment,Contact angle relaxation,XPS analysis,Donor-acceptor complex,TiO2 thin films
更新于2025-09-23 15:22:29
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Impact of Alkyl Side Chain Length on Doping Kinetics, Thermopower and Charge Transport Properties in Highly Oriented F4TCNQ-Doped PBTTT films
摘要： Doping of polymer semiconductors such as PBTTT with acceptor molecules such as F4TCNQ is widely used to tune the charge transport and thermoelectric (TE) properties in thin films. However, the mechanism of dopant insertion in the polymer matrix, the insertion kinetics and the ultimate doping levels reached have been investigated only marginally. This contribution addresses the impact of alkyl side chain length on the doping mechanism of a series of PBTTTs with linear side chains ranging from n-octyl to n-octyldecyl. The study focuses on thin films oriented by high temperature rubbing and sequentially doped in F4TCNQ solution. Structure-property correlations are established as a function of side chain length by a combination of Transmission Electron Microscopy, polarized UV-Vis-NIR spectroscopy and charge transport / thermopower measurements. Intercalation of F4TCNQ into the layers of side chains results in the expansion of the lattice along the side chains and the contraction along the π-stacking direction for all polymers. The extent of lattice expansion decreases with increasing side chain length. UV-vis-NIR spectroscopy demonstrates integer charge transfer for all investigated PBTTTs. The doping kinetics and final doping level depend on both the side chain length and packing. Highly disordered n-octyl and crystalline n-octyldecyl side chain layers tend to hamper dopant diffusion in the side chain layers contrary to n-dodecyl side chains that can host the highest proportion of dopants. Consequently, the best TE properties are observed for C12-PBTTT films. Alignment of the polymers enhances significantly the TE performance by increasing the charge conductivity and the thermopower along the rubbing direction. Aligned films of C12-PBTTT show charge conductivities of 193 S/cm along the rubbing direction and power factors of approximately 100 μW.m-2.K-1 versus a few μW.m-2.K-1 for non-oriented films.
关键词： Thin films,Structure,Organic Thermoelectric,Conducting Polymers,Doping.
更新于2025-09-23 15:22:29
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Copper Nanowire Dispersion through an Electrostatic Dispersion Mechanism for High-Performance Flexible Transparent Conducting Films and Optoelectronic Devices
摘要： Highly dispersed copper nanowire (CuNW) is an essential prerequisite for its practical application in various electronic devices. At present, the dispersion of CuNW is almost realized through the steric hindrance effect of polymers. However, the high post-treatment temperature of polymers makes this dispersion mechanism impractical for many actual applications. Here, after investigating the relationships between the electrostatic dispersion force and influence factors, an electrostatic dispersion mechanism is refined by us. Under the guidance of this mechanism, high dispersion of CuNW and a record low post-treatment temperature (80 ℃ ) are realized simultaneously. The high dispersity endows CuNW with good stability (–45.66 mV) in water-based ink, high uniformity (65.7 ± 2.5 Ω sq-1) in the prepared transparent conducting film (TCF) (23 cm × 23 cm) and industrial film-preparation process which are the issues that hinder the widespread application of CuNW-based TCF at present. The low post-treatment temperature makes CuNW possible for applying on any substrate. In addition, the charge modifier, 2-mercaptoethanol, enables CuNW to resist oxidation well. Finally, flexible optoelectronic devices employing the CuNW film as the electrode are fabricated and show efficiencies comparable to those of optoelectronic devices on ITO/glass.
关键词： copper nanowires,flexible optoelectronic devices,electrostatic dispersion mechanism,transparent conducting films,post-treatment temperatures
更新于2025-09-23 15:22:29