修车大队一品楼qm论坛51一品茶楼论坛,栖凤楼品茶全国楼凤app软件 ,栖凤阁全国论坛入口,广州百花丛bhc论坛杭州百花坊妃子阁

oe1(光电查) - 科学论文

过滤筛选

出版时间
  • 2018
研究主题
  • tumor imaging
  • conductivity
  • MRI
  • EPT
  • Electrical properties tomography
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Ghent University
1602 条数据
?? 中文（中国） ▾

  • Complex Optical and Thermal Studies on As-Synthesized Conducting Polythiophene

    摘要： A series of conducting polythiophene (PTh) samples have been synthesized using an in situ chemical oxidative polymerization technique in aqueous solution. The characterization of the as-synthesized optimized sample has been carried out by Fourier transform infrared spectroscopy, x-ray diffraction and thermogravimetric–differential thermal analysis techniques. Also, the complex optical parameters of all the as-synthesized polymeric samples have been investigated by using ultraviolet–visible spectroscopy. The as-synthesized polymeric samples exhibited absorption around 220–280 nm. The optical band gap was found to ranges from 5.06 eV to 5.24 eV. The maximum optical conductivity for the sample with a stoichiometric ratio of thiophene to FeCl3 of 70:30 wt.% was found to be 5.973 9 108 S cm?1 at 280 nm. The experimental results reveal that the thermal and optical performance of conducting PTh can be dramatically enhanced for the sample with a stoichiometric ratio of thiophene to FeCl3 of 70:30 wt.%. The improved complex optical properties of as-synthesized samples of conducting PTh validate their potential utilization in optoelectronic devices.

    关键词： thermal analysis,complex optical properties,Polythiophene

    更新于2025-11-19 16:56:35

  • Synthesis, Crystal Structure, and Photocatalytic Properties of a Zinc(II) Coordination Polymer Based on 3-Hydroxy-2-pyridinecarboxylic Acid

    摘要： The zinc(II) compound, [Zn3(HL)6]n (1) (H2L = 3-hydroxypyridine-2-carboxylic acid) was synthesized by a solvothermal reaction of Zn(NO3)2·6H2O and 3-hydroxypyridine-2-carboxylic acid as raw materials. The structure of complex 1 was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, as well as powder X-ray diffraction. X-ray structure analysis demonstrates that the complex crystallizes in the monoclinic system, space group P21/n. There are three zinc ions in the asymmetric unit, which are either five-coordinate or six-coordinate. The asymmetric units are further bridged by the carboxylate of the organic ligands, featuring a 2D framework. The solid state diffuse-reflectance UV/Vis spectra reveals that complex 1 has semiconducting nature with the energy bandgap (Eg) estimated to be 3.11 eV. The photocatalytic properties of complex 1 in degradation of organic dyes were further investigated. Results showed that the complex could degrade 54 % of the dye methylene blue solution within 120 min under UV irradiation light and reused for five times without the decline of the photocatalytic activity.

    关键词： Crystal structure,Photocatalytic properties,Zinc,3-Hydroxypyridine-2-carboxylic acid,Solvothermal reaction,Coordination polymer

    更新于2025-11-19 16:56:35

  • Improvement of Optical and Thermal Properties for Quantum Dots WLEDs by Controlling Layer Location

    摘要： The inorganic halide perovskite quantum dots (QDs) have been considered as a promising substitute for white light-emitting diodes (WLEDs). In this article, the green CsPbBr3 QDs and red K2SiF6:Mn4+ (KSF) phosphor were used to fabricate the conversion layers. Because the layers location is fundamental to the absorption priority of blue light, the location of KSF and QDs were controlled and the QDs-up type and QDs-down type WLEDs were made. The optical power, luminous efficiency, CCE and luminous intensity in the middle of QDs-up type are 13.83 mW, 13.54 lm/W, 11.94% and 2.65 cd, meaning 24.26%, 25.72%, 2.63% and 23.83% higher than those of QDs-down type, respectively. In addition, the QDs-up type has a lower correlated color temperature (CCT) shift of 734 K and a decreased highest temperature of 56.8℃ (51.5% and 14.9% lower). These key property differences indicate that the QDs-up type is more suitable for the application in display and backlight. In order to explore the reasons for these differences, the emission spectra, CCE, reflection rate, absorption rate and temperature curves of QDs or KSF films were also analyzed, which provided a better understanding of designing package structures.

    关键词： layer location,thermal properties,quantum dots WLEDs,optical properties

    更新于2025-11-19 16:46:39

  • Indoline and benzothiazole-based squaraine dye-sensitized solar cells containing bis-pendent sulfonate groups: Synthesis, characterization and solar cell performance

    摘要： Two new symmetric squaraine sensitizers (SQTHZ and SQIND) carrying benzothiazole and indoline moieties as strong electron donating groups to inject the electron into the TiO2 nanoparticles were tested as DSSC. The theoretical calculations and absorption results show that the electron density of LUMO of SQTHZ is delocalized in the whole chromophore, leading to strong electronic coupling between SQTHZ sensitizer and the conduction band of TiO2. Furthermore, the presence of long alkyl chain with pendent bis-SO3- groups would inhibit recombination and decrease the dye aggregation. Interestingly, SQTHZ displayed UV-Vis and NIR absorption at a longer wavelength compared to SQIND. This structure feature, as well as optical properties, would lead to improved efficiency of dye-sensitized solar cell with overall better photovoltaic performance (η of 3.31 %, Jsc of 7.65 mA/ cm2, Voc of 0.59, ff of 0.71 and IPCE of 47 % at 674 nm) compared to SQIND.

    关键词： Photoelectrochemical properties,DFT,Dye-sensitized solar cell,Symmetric squaraine dyes

    更新于2025-11-19 16:46:39

  • A Wide Temperature Insensitive Piezoceramics for High-Temperature Energy Harvesting

    摘要： One of the key challenges in the development of high-temperature energy harvesting (HTEH) technology is to clarify the relationship between temperature-dependent material parameters and device power generation capabilities. However, at present, the research on temperature stability of piezoceramics mainly relies on thermal annealing technology, which cannot follow the actual temperature dependence of the piezoelectricity, and it is even more difficult to predict the temperature stability of HTEH. To shed light on this field, here, (1-x)BiScO3-xPbTiO3 system was chosen for building HTEH material, and the temperature dependent electrical parameters, such as d33, εr, and g33, have been measured by multiple in-situ techniques. It was found that the synergistic effect of d33 and εr with temperature helps to obtain a stable g33 value in a wide temperature range. Moreover, in the mode of the cantilever-type energy harvester, a stable output voltage was obtained at x=0.64 harvester with less than 20% change over a broad temperature range of 100-250 oC, and it was verified that the temperature stability of g33 is crucial to the operation stability of HTEH devices.

    关键词： in-situ techniques,piezoelectric materials/properties,energy harvesting,thermal properties

    更新于2025-11-14 17:28:48

  • [Lecture Notes in Mechanical Engineering] Advances in Thin Films, Nanostructured Materials, and Coatings (Selected Papers from the 2018 International Conference on “Nanomaterials: Applications & Properties”) || Stain Effect on the Properties of Polar Dielectric Thin Films

    摘要： Low cost scalable processing and substrates are critical for optimized polar dielectric performance of functional oxide thin ?lms if they are to achieve commercialization. Here, we present a comprehensive investigation of the role low-cost MgO, Al2O3, SrTiO3 and Si substrates on the structural and electrical properties of sol-gel derived SrTiO3 (ST) and K0.5Na0.5NbO3 (KNN) thin ?lms. The substrate is found to have a strong effect on the stress/stain state and, consequently, on the dielectric and ferroelectric response of the ?lms. A tensile stress induced in-plane by the thermal expansion mismatch between the substrates and the ?lms observed for ST and KNN ?lms deposited on platinized Al2O3 and Si substrates, respectively, lowers the relative permittivity and remanent polarization values in the parallel plate capacitor geometry. In contrast, a compressive stress/strain observed for ST ?lms deposited on MgO/Pt and KNN ?lms on SrTiO3/Pt substrates result in superior polarization and dielectric permittivity, corresponding to enhanced out-of-plane displacement of Ti4+ ions in ST ?lms and Nb5+ ions in KNN ?lms. It is thus demonstrated that for polycrystalline polar dielectric thin ?lms the relative permittivity and polarization may be optimized through an induced compressive stress state.

    关键词： Dielectric properties,Sol-gel,Thin ?lms,Stress/strain,Thermal expansion,Ferroelectric hysteresis

    更新于2025-11-14 17:28:48

  • Controlling colloidal processing of (K,Na)NbO3-based materials in aqueous medium

    摘要： K0.5Na0.5NbO3-based materials are serious candidates to replace lead-based piezoceramics since they show excellent electrical and piezoelectric properties. The tape casting technique can be used to obtain highly textured KNN-based ceramics; however, despite industrial and environmental advantages of water-based processing, there are not reports about the control of colloidal processing conditions to obtain optimized K0.5Na0.5NbO3-based slurries in aqueous medium. This paper reports a procedure for controlling colloidal processing conditions to obtain optimized (K0.5Na0.5)0.97Li0.03Nb0.8Ta0.2O3 suspensions. Zeta potential and cationic solubility measurements as a function of pH showed that pH 8.5 is adequate for controlling colloidal stability and rheological behavior of aqueous suspensions, while flow curves analysis allowed optimizing processing parameters, such as, powder content, amount of deflocculant and binder, and sonication time. Optimized colloidal suspensions were prepared and used to obtain high quality tapes. Processed ceramics from these stacked tapes show equivalent properties to those processed directly from powders, which demonstrates the effectiveness of the colloidal route reported here.

    关键词： Aqueous tape casting,KNN,Lead-free,Rheological properties,Colloidal suspensions

    更新于2025-11-14 17:28:48

  • Reorientational dynamics of organic cations in perovskite-like coordination polymers

    摘要： Here we report the dynamics of organic cations as guest molecules in a perovskite host-framework. The molecular motion of CH3NH3+ (MAFe), (CH3)2NH2+ (DMAFe) and (CH3)3NH+ (TrMAFe) in the cage formed by KFe(CN)63? units was studied using a combination of experimental methods: (i) thermal analysis, (ii) dielectric and electric studies, (iii) optical observations, (iv) EPR and 1H NMR spectroscopy and (v) quasielastic neutron scattering (QENS). In the case of MAFe and TrMAFe, the thermal analysis reveals one solid-to-solid phase transition (PT) and two PTs for the DMAFe crystal. A markedly temperature-dependent dielectric constant indicates the tunable and switchable properties of the complexes. Also, their semiconducting properties are confirmed by a dc conductivity measurement. The broadband dielectric relaxation is analyzed for the TrMAFe sample in the frequency range of 100 Hz–1 GHz. QENS shows that we deal rather with the localized motion of the cation than a diffusive one. Three models, which concern the simultaneous rotation of the CH3 and/or NH3 group, π-flips and free rotations of the organic cation, are used to fit the elastic incoherent structure factor. The 1H NMR spin–lattice relaxation time for all compounds under study, as well as the second moments, has been measured in a wide temperature range. In all studied samples, the temperature dependence of the second moment of the proton NMR line indicated the gradual evolution of the molecular movements from the rigid state up to a highly disordered one.

    关键词： quasielastic neutron scattering,phase transitions,perovskite,coordination polymers,dielectric properties,NMR spectroscopy,dynamics,organic cations

    更新于2025-11-14 17:28:48

  • Luminescence and electrical properties of Eu-modified Bi <sub/>0.5</sub> Na <sub/>0.5</sub> TiO <sub/>3</sub> multifunctional Ceramics

    摘要： The Eu3+ modified Bi0.5Na0.5TiO3 (BNT) ceramics have been fabricated by the solid-state reaction method. The impact of Eu3+ doping on the structure, photoluminescence and electrical properties has been studied by XRD, SEM, PL spectra and LCR meter. X-ray diffraction analysis reveals that the crystal structure of the samples is well matched with the trigonal perovskite, and the optimal temperature of pre-sintering is 880°C. The Eu3+ doped BNT ceramics show excellent red fluorescence at 614nm corresponding to the 5D0→7F2 transition of Eu3+ under 466nm excitation and relatively long fluorescence lifetime. The BNT-0.02Eu ceramic density is up to 5.68g/cm3 and the relative density is up to 94.6% with sintering temperature 1075°C. The piezoelectric constant (d33) of samples has been significantly improved up to 110pC/N by Eu3+ doping. The BNT-0.03Eu ceramic pre-sintered at 880°C and sintered at 1050°C has good dielectric properties and excellent luminescence properties. Eu3+ doped BNT ceramics make it potential applications for novel integrated optical-electro and multifunctional devices.

    关键词： luminescence,electrical properties,Bismuth sodium titanate (Bi0.5Na0.5TiO3),lead-free ceramics

    更新于2025-11-14 17:28:48

  • Improved densification behavior and energy harvesting properties of low-temperature sintered (Ba, Ca)(Zr, Ti)O3 piezoceramics with a CuO additive

    摘要： Piezoelectric energy harvesting has recently attracted substantial interest because of its ability to provide sustainable power for devices that consume very small amounts of energy. In this work, we propose a CuO-doping strategy to develop environmentally friendly (Ba, Ca)(Zr, Ti)O3 (BCZT) piezoelectric energy harvesters with both low sintering temperatures and excellent power generation performance. The CuO dopant greatly promoted the densification behavior of BCZT ceramics, yielding a densified and fine-grained microstructure at a sintering temperature reduced by 125°C compared to that of undoped BCZT. Moreover, CuO addition substantially reduced the domain size compared to that of the undoped BCZT and thus facilitated domain switching in the ceramics. While maintaining the Curie temperature (Tc) at ~120oC, 0.50 mol% CuO-doped ceramics exhibited significantly enhanced electromechanical properties with a figure of merit d33×g33 of 6661×10-15 m2/N, high-field piezoelectric constant d33* of 873 pm/V, electromechanical coupling factor kp of 0.53 and energy conversion efficiency η of 97%. A high power density of 1.8 μW/mm3, which corresponds to a ~360% improvement relative to that of the undoped BCZT, was achieved from 0.50 mol% CuO-doped BCZT energy harvesters at 10 m/s2 acceleration. These findings suggest the tremendous potential of CuO-doped (Ba, Ca)(Zr, Ti)O3 piezoceramics in high-power-density energy harvesting applications.

    关键词： A. Sintering,C. Electrical properties,D. BaTiO3,B. Microstructure

    更新于2025-11-14 17:28:48