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- 2019
- low-temperature electronics
- junction field-effect transistors
- differential operational amplifier
- LTspice environment
- differential stage
- common-mode rejection ratio
- class AB operation
- optimization of analog electronic circuit
- operational amplifier
- LTspice environment
- Electronic Science and Technology
- Don State Technical University
- Southern Federal University
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Telescoping synthesis and goldilocks of CZTS nanocrystals
摘要： Facile, low-temperature synthesis of kesterite CZTS nanocrystals (NCs) using single solvent by heating up approach is presented for the first time. Temperature and time dependence on the structural, morphological and compositional properties are investigated in detail. The size of the NCs was found to increase from 15 to 45 nm with increases in the reaction temperature. From the structural analysis, secondary and ternary phases were detected at less reaction time, and pure phase of CZTS was obtained at 3 h. On the basis of the detailed time-dependent phase evolution, a plausible formation mechanism of CZTS NCs was proposed. The sequence of CZTS phase evolved from Cu2S phase to Cu2SnS3 intermediate compound and finally to pure kesterite CZTS. The optimal composition of Cu/(Zn+Sn) and Zn/Sn ratio was obtained at 3 h. The calculated band gap was found to be 1.5 eV which is an optimum value for solar cell applications. Thus, the results revealed that the reaction temperature and time played a determining role to obtain pure phase CZTS with controlled composition and optimum bandgap.
关键词： Low-temperature,Heating up approach,Nanocrystals,CZTS
更新于2025-09-10 09:29:36
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Low-Temperature Effect on the Electronic Structure and Spectral-Fluorescent Properties of Highly Dipolar Merocyanines
摘要： Absorption and fluorescence spectra of a vinylogous series of reversely solvatochromic merocyanines based on benzimidazole and malononitrile have been studied in frozen ethanol solutions at 77 K. It is found that they possess negative thermochromism – in contrast to both positively solvatochromic merocyanines and negatively solvatochromic symmetrical ionic polymethines – and even stronger negative thermofluorochromism. It has been deduced from the spectral data, that at low temperature their electronic structure becomes more dipolar, deviating substantially from the virtual ideal polymethine in both the ground and excited states. At that, owing probably to high polarity and ordering of frozen ethanol, the dipolarity of the studied merocyanines increases with the polymethine chain lengthening – the tendency not observed for them in common solvents. The conclusions, based on the spectra data analysis, have been verified by the (TD)DFT–PCM simulations of the dyes within the four-level scheme of electronic transitions.
关键词： Low-Temperature Effect,Spectral-Fluorescent Properties,Merocyanines,Quantum Chemistry,Electronic Structure,Molecular Structure,Spectroscopy
更新于2025-09-10 09:29:36
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Low-Temperature CVD Graphene Nanostructures on Cu and Their Corrosion Properties
摘要： Chemical vapor deposition (CVD) graphene is reported to effectively prevent the penetration of outer factors and insulate the underneath metals, hence achieving an anticorrosion purpose. However, there is little knowledge about their characteristics and corresponding corrosion properties, especially for those prepared under different parameters at low temperatures. Using electron cyclotron resonance chemical vapor deposition (ECR-CVD), we can successfully prepare graphene nanostructures on copper (Cu) at temperatures lower than 600 ?C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and potentiodynamic polarization measurements were used to characterize these samples. In simulated seawater, i.e., 3.5 wt.% sodium chloride (NaCl) solution, the corrosion current density of one graphene-coated Cu fabricated at 400 ?C can be 1.16 × 10?5 A/cm2, which is one order of magnitude lower than that of pure Cu. Moreover, the existence of tall graphene nanowalls was found not to be beneficial to the protection as a consequence of their layered orientation. These correlations among the morphology, structure, and corrosion properties of graphene nanostructures were investigated in this study. Therefore, the enhanced corrosion resistance in selected cases suggests that the low-temperature CVD graphene under appropriate conditions would be able to protect metal substrates against corrosion.
关键词： graphene films,corrosion,copper,low temperature,chemical vapor deposition
更新于2025-09-10 09:29:36
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Low-temperature preparation of a N-TiO2/macroporous resin photocatalyst to degrade organic pollutants
摘要： Highly active TiO2 photocatalysts prepared at a low temperature are promising reagents to degrade organic pollutants. Moreover, the addition of macroporous resins should overcome the poor adsorption properties of TiO2. Here we prepared N-doped TiO2/macroporous resin composites at low temperatures using a hydrothermal-assisted sol–gel method. The results show that the composites have a spherical appearance, which is controlled by the macroporous resin. The composites exhibit high specific surface areas, and the microstructure can be tuned by the temperature. N can be doped into the TiO2 crystal by substitution of oxygen at a lower temperature. N-doped TiO2 particles are distributed on the surface with a dominant crystal form of anatase. The composite prepared at 200 °C gave the best performance for the photocatalytic degradation of rhodamine B, with removal efficiency of 74.8% following 240-min irradiation.
关键词： Low temperature,Macroporous resin,Rhodamine B,TiO2,Photocatalysis
更新于2025-09-09 09:28:46
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[IEEE 2018 13th International Congress Molded Interconnect Devices (MID) - Würzburg, Germany (2018.9.25-2018.9.26)] 2018 13th International Congress Molded Interconnect Devices (MID) - Low-Temperature Sintering of Nanometal Inks on Polymer Substrates
摘要： Digital non-contact-printing technologies such as inkjet or Aerosol Jet are becoming more and more interesting for the manufacturing of electronic components due to their benefits such as easy variation of printing layouts, short process chains without masks, large variety of usable substrates and inks - frequently based on nano metals - and a certain 3D capability. In this contribution options are discussed to sinter nano metal inks such as Ag, Au, and CuNi inks at low temperature, thus enabling the use of temperature sensitive polymer substrates like PC, PS, or PMMA. This includes the addition of chemical agents as well as light-based sintering methods such as photonic curing or laser sintering. Finally some application examples are presented.
关键词： Digital printing,laser sintering,photonic curing,low-temperature sintering,nano metal inks
更新于2025-09-09 09:28:46
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Solution-processed inorganic p-channel transistors: Recent advances and perspectives
摘要： For decades, inorganic n-type metal-oxide semiconductors have attracted great interest across a wide range of applications due to their excellent electrical property, low cost, high optical transparency, and good ambient stability. The next attention has focused on the development of high-performance p-type semiconductors with comparable opto/electric properties to n-type counterparts. This paper provides a comprehensive overview of recent progress in solution-processed inorganic p-type semiconductors that can be applied as channel layers in thin-?lm transistors and complementary metal-oxide semiconductor-based integrated circuits. We ?rst introduce conventional p-type oxide semiconductors and review their achievements on related devices. Then, we pay a speci?c focus on emerging (pseudo)halide materials for realization of transparent, low-temperature and high-performance printable electronics and circuits.
关键词： Inorganic p-type semiconductor,Low-temperature process,Solution process,Field-e?ect transistor,Printable electronics
更新于2025-09-09 09:28:46
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Er-doped antimonite Sb2O3?PbO?ZnO/ZnS glasses studied by low-temperature photoluminescence spectroscopy
摘要： Antimonite glasses Sb2O3?PbO?ZnO/ZnS doped with ErCl3 within the range of 0.25-1.0% were prepared and investigated by means of transmission, photoluminescence excitation and photoluminescence (PL) spectroscopy. In the studied glasses, the wavelength of 522 nm was found to be the most suitable for PL excitation of Er3+ ions doped in both the NIR and VIS spectral ranges. The PL spectra excited by wavelengths at 522 and/or 514.5 nm were measured at room and low temperatures (4 K) in the wavelength range of 400–1700 nm. Low-temperature PL spectroscopy allowed us to observe both the broad luminescence of the host glass centered at around 1050 nm and the narrow emissions caused by Er3+ ions. Special attention was given to the wavelengths where the broad-band luminescence of the host overlaps with 4f–4f transitions within Er3+ ions. A broad PL band of the host glass was observed together with a superimposed narrow emission band at 985 nm (4I11/2? 4I15/2) and a narrow absorption dip at about 970 nm (4I15/2? 4I11/2). This absorption dip is a direct experimental evidence of energy transfer from the electronic structure of the host glass to 4f states of doped-in Er3+ ions. The strongest PL band at 1530 nm, representing transition from the lowest excited manifold 4I13/2 to the ground state manifold 4I15/2 was measured at 300 K and 4 K. The broadening at elevated temperature occurs primarily in the high energy part of the spectrum due to thermal excitation of electrons within the 4I13/2 manifold.
关键词： photoluminescence excitation spectroscopy,broad-band luminescence,low-temperature photoluminescence spectroscopy,erbium,antimonite glasses
更新于2025-09-09 09:28:46
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Temperature Dependence of the Luminescence Spectra of a 5CB Liquid Crystal and its Phase Transitions
摘要： The spectroluminescence properties of 4cyano4'pentylbiphenyl CH3(CH2)4(C6H4)2CN (5CB) were studied in the temperature range 4.2–297 K. A red shift of the fluorescence spectrum was noted with increasing temperature. The long-wavelength shifts in these spectra were also analyzed. Comparison of the temperature dependence curves for the emission at the band maxima λmax and their halfwidths Δλ/2 in the fluorescence spectra and the results of a differential scanning calorimetry (DSC) study showed that phase transitions occur in the 5CB liquid crystals at ~230 and ~260 K.
关键词： liquid crystal,phase transition,differential scanning calorimetry,luminescence,low temperature,conformation change
更新于2025-09-09 09:28:46
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Influence of Bi Substitution on the Microstructure and Dielectric Properties of Gd3Fe5O12 Ceramics
摘要： The exponential growth in microwave communications in recent years demands innovations and high yield microwave materials. Rare earth iron garnets are well known for their remarkable performance in microwave devices owing to their superior features. In this work we investigate the microstructure and dielectric properties of Bismuth substituted Gd3Fe5O12 ceramics prepared by the conventional solid state reaction route. The variation of lattice parameter, microstructure, permittivity, quality factor and temperature coef?cient of resonant frequency (sf) of Gadolinium Iron Garnet (GIG) with several concentrations of bismuth was investigated. The Bi3+ ion is effectively incorporated into Gadolinium Iron Garnet, due to which the sintering temperature is considerably reduced, and the densi?cation is improved signi?cantly. Moreover, with increase in Bi concentration, the dielectric constant of GIG also increases, while the quality factor is slightly reduced, which is correlated with the higher ionic polarizability of bismuth. At an appreciably low sintering temperature of 1050(cid:2)C, Gd2BiFe5O12 possess a porosity corrected relative permittivity value of 27.3 ± 0.2, unloaded quality factor (Qu 9 f) of 2990 ± 60 GHz (f = 7.3 GHz) and temperature coef?cient of resonant frequency + 60 ± 1 ppm/(cid:2)C.
关键词： microstructure,Low-temperature sintering,microwave dielectric properties,garnet structure
更新于2025-09-09 09:28:46
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Enhancement of the absorption bands in the infrared spectra of low-temperature uracil films by interference
摘要： An experimental method that enables significant enhancement of the bands in the IR absorption spectra of low-temperature films, using standard equipment for matrix isolation, was proposed. The effect is achieved due to the interference amplification of an electromagnetic wave using a sublayer of Ar film. IR Fourier spectra of low-temperature films of uracil (Ur) molecules were obtained in the range of 2000–500 cm–1, with a resolution of 3 cm–1. Thin Ur films with thickness of approximately 0.3 μm were grown at low temperatures on the surface of argon films of thickness of 2.3 and 1.1 μm. An enhancement in the spectral range of 1250–500 cm–1 was recorded for the first bilayer structure, and in the range of 2000–500 cm–1 for the second one. As a result of amplification in the spectrum of the low-temperature uracil film, absorption bands in the range of out-of-plane deformation vibrations of 1000–500 cm–1 were recorded for the first time. It was found that the out-of-plane fundamental NH modes of Ur groups are most sensitive to changes in the crystal structure of the film. It was shown that the absorption spectrum of the Ur film heated to room temperature differs from the spectrum of the Ur crystal obtained from the solution, which indicates a difference in their structures.
关键词： uracil,interference amplification,low-temperature films,absorption bands,infrared spectra
更新于2025-09-09 09:28:46