- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Self-Assembly Behavior of an Oligothiophene-Based Conjugated Liquid Crystal and Its Implication for Ionic Conductivity Characteristics
摘要： In this work, a joint experimental and computational study on the synthesis, self-assembly, and ionic conduction characteristics of a new conjugated liquid crystal quaterthiophene/poly(ethylene oxide) (PEO4) consisting of terminal tetraethyleneglycol monomethyl ether groups on both ends of a quaterthiophene core is performed. In agreement with molecular dynamic simulations, temperature-dependent grazing-incidence wide angle X-ray scattering and X-ray diffraction indicate that the molecule spontaneously forms a smectic phase at ambient temperature as characterized both in bulk and thin film configurations. Significantly, this smectic phase is maintained upon blending with bis(trifluoro-methanesulfonyl)imide as ion source at a concentration ratio up to r = [Li+]/[EO] = 0.05. Nanosegregation between oligothiophene and PEO moieties and π–π stacking of thiophene rings lead to the formation of efficient 2D pathways for ion transport, resulting in thin-film in-plane ionic conductivity as high as 5.2 × 10?4 S cm?1 at 70 °C and r = 0.05 as measured by electrochemical impedance spectroscopy. Upon heating the samples above a transition temperature around 95 °C, an isotropic phase forms associated with a pronounced drop in ionic conductivity. Upon cooling, partial and local reordering of the conducting smectic domains leads to an ionic conductivity decrease compared to the as-cast state.
关键词： oligothiophene,self-assembly,liquid crystal,ionic conductivity,π–π interactions
更新于2025-09-10 09:29:36
-
Effect of stacking faults and surface roughness on the thermal conductivity of InAs nanowires
摘要： Low thermal conductivity and high power factor are desirable for thermoelectric materials. These properties can be achieved by patterning devices into nano-structures such as nanowires (NWs). The thermal conductivity can be further reduced by altering the NW geometry through the introduction of surface roughness (SR) or stacking faults (SFs). In this paper, relaxation times for scattering of phonons at SFs and SR are developed to accurately compute the impact of both effects on the thermal conductivity of InAs NWs with different diameters. It is found that similar reductions of the thermal conductivity can be obtained with SFs instead of SR. For the shortest possible distance between SFs along a NW, the room temperature thermal conductivity can be reduced to 25% compared to an ideal NW. For a NW with rough surface, a more than 80% decrease of the thermal conductivity is possible for specific roughness profiles. All available experimental data on the lattice thermal conductivity of InAs NWs confirm the theoretical models and simulation results.
关键词： surface roughness,thermal conductivity,phonon scattering,stacking faults,InAs nanowires
更新于2025-09-10 09:29:36
-
[IEEE 2018 EMF-Med 1st World Conference on Biomedical Applications of Electromagnetic Fields (EMF-Med) - Split, Croatia (2018.9.10-2018.9.13)] 2018 EMF-Med 1st World Conference on Biomedical Applications of Electromagnetic Fields (EMF-Med) - In Vivo Electrical Conductivity Imaging of Animal Tumor Model at 7T using Electrical Properties Tomography
摘要： Ex vivo studies have shown that various diseases alter the electrical properties of tissues compared to healthy nearby tissues. Therefore, electrical conductivity can be used as a diagnostic parameter for e.g. tumor diagnosis. For in vivo measurements, magnetic resonance electrical properties tomography (MREPT) was used and electrical conductivity was reconstructed from the B1+ phase. The technique was first evaluated using homogeneous and heterogeneous phantoms. Then a mouse with a tumor was scanned and the conductivity is reconstructed from the B1+ phase map. The reconstructed conductivity in the phantom experiments was in good agreement with the target conductivity map and the conductivity map of the animal revealed good agreement with the co-axial probe measurement. Our work confirms the possibility of accurate in vivo conductivity assessment in disease.
关键词： tumor imaging,conductivity,MRI,EPT,Electrical properties tomography
更新于2025-09-10 09:29:36
-
Effect of dielectric and conductive targets on plasma jet behaviour and thin film properties
摘要： A double layer DBD plasma jet driven by a pulsed generator is used for SiOx thin film deposition. The effects of dielectric and conductive targets on discharge behavior and film properties are analyzed. Different optical emission of the plasma jet at different positions are characterized. Film surface morphology, composition properties is studied. Results show that the relative optical emission intensities of Si, O, Ar and N2, as well as and thickness are measured for different targets. The excitation temperature (Texc), vibrational temperature (Tvib) fraction of N2 is added to the working gas (argon) to modulate film growth rate. The electrical property and Texc, Tvib and Trot are higher for the PMMA target between the high voltage electrode and the grounded electrode and rotational temperature (Trot) are calculated. The relationship between the discharge behavior and the film as optical transparency, sufficient insulation strength and scratch resistance1. The application of SiOx films is found in many fields, for example, microelectronics 2, biomedicine 3, food packaging 4 and high voltage insulation5. Plasma-enhanced chemical vapor deposition (PECVD) is one of the well-established methods for (referred to as the H-G region). However, Tvib and Trot appear to be higher on the surface of the copper (conductive) target. The morphology of SiOx film is different: nanoparticles are formed on the PMMA (dielectric) target while the synthesis of SiOx films. It typically involves a low pressure non-thermal plasma system. A low-pressure SiOx film is higher on the copper target. The presence of PMMA at the downstream of the plasma can be dense amorphous film is formed on the copper target. With the same depositing parameters, the thickness of the through the H-G region. Although the presence of a dielectric target enhances the discharge in the H-G region, considered as a small capacitor with a large resistance, which inhibits the current into the primary circuit passing the charge accumulation on the PMMA surface limits the film growth. These results may contribute to the development of next-generation plasma surface modification technologies for diverse applications in electronics, Siloxane (SiOx) films are of great interest because of their excellent physical and chemical properties such
关键词： Target conductivity,Plasma jet,Film deposition,TEOS dissociation,Discharge behavior
更新于2025-09-10 09:29:36
-
Ionic Conduction Response under Extending-Deformation of β-AgI Thin Films
摘要： Tensile stress was applied to β-AgI thin film prepared on a polyethylene terephthalate film, and the ion conduction response in the direction of the tensile extension was investigated. The ionic conductivity of the β-AgI thin film decreases and the activation energy for ionic conduction increases with increasing extension ratio. This behaviour is attributed to the modulation of the crystal framework by the extension of the AgI thin film.
关键词： conductivity,thin film,extending-deformation,beta-AgI
更新于2025-09-10 09:29:36
-
Growth of Si-doped AlN on sapphire (0001) via pulsed sputtering
摘要： The Si-doped AlN films were grown on sapphire (0001) by pulsed sputtering deposition (PSD), and their structural and electrical properties were investigated. A combination of PSD and high-temperature annealing process enabled the growth of high-quality AlN (0001) epitaxial films on sapphire (0001) substrates with atomically flat stepped and terraced surfaces. The transmission electron microscopy observations revealed that the majority of the threading dislocations in AlN belonged to the mixed- or edge-type, with densities of 2.8 × 108 and 4.4 × 109 cm?2, respectively. The Si-doping of AlN by PSD yielded a clear n-type conductivity with a maximum electron mobility of 44 cm2 V?1 s?1, which was the highest value reported for AlN that was grown on sapphire. These results clearly demonstrated the strong potential of the PSD technique for growing high-quality conductive n-type AlN on sapphire.
关键词： n-type conductivity,Si-doped AlN,pulsed sputtering deposition,electron mobility,sapphire
更新于2025-09-10 09:29:36
-
Study of complex impedance spectroscopic properties of La <sub/> 0.7? <i>x</i> </sub> Dy <i> <sub/>x</sub></i> Sr <sub/>0.3</sub> MnO <sub/>3</sub> perovskite oxides
摘要： The dysprosium perovskite La0.72xDyxSr0.3MnO3 [LSMO] and 0.03 [LDSMO]) compounds were prepared by the sol–gel reaction and characterized by the X-ray diffraction technique. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 311–356 K and 209–5 (cid:2) 107 Hz, respectively, by means of impedance spectroscopy. The ac and dc conductivities were studied to explore the mechanisms of conduction of LSMO and LDSMO. The insertion of a small amount of Dy3t in the La-site of LSMO perovskite oxide increases the value of the activation energy from 0.2106 to 0.5357 eV and enhances electrical resistivity values for almost two orders of magnitude.
关键词： the non-overlapping small polaron tunneling,impedance spectroscopy,correlated barrier hopping,modulus,ac conductivity
更新于2025-09-10 09:29:36
-
[IEEE 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Evaluation of the Thermal Properties for the Design of the Semiconductor Device
摘要： The more semiconductor devices progress, the more importance of caring about heat dissipation from heat generation increase. This is called “Thermal design”. Thermophysical property values like thermal conductivity and thermal expansion coefficient are used as information for thermal design. The specified values in a brochure or literature data of similar materials are usually used as the thermophysical property values for the thermal design. However, when those values are used for simulation, the results may be wrong because an actual measured value such as rate of conduction of heat of an ingredient is different from literature data or the nominal value in many cases. It is thought that there are a lot of cases without considering directionality of an ingredient (anisotropy) and influence of joint interface. We propose that we should measure these values with considering anisotropy, size effect and the bonding state and utilize them for thermal design of electronic materials used in a semiconductor device.
关键词： Thermal diffusivity,Thermal conductivity,Thin film,Thermal resistance,Bonding layer,Anisotropy,Thermal design,Transient thermal measurement
更新于2025-09-10 09:29:36
-
The Influence of the V2O5 · GeO2 Glass Phase on the Properties of AgI Nanolayers
摘要： Using X-ray phase analysis and impedance monitoring, it was shown that for a nanolayered structure, softened glass (V2O5 ? GeO2) can take an imprint from AgI lattice and retain it while being cooled to temperatures below Tg.
关键词： nanolayers,solid electrolytes,phase transitions,interfacial interactions,ionic conductivity
更新于2025-09-10 09:29:36
-
Functional properties of LaxCe1?xO2?δ nanocrystals and their bulk ceramics
摘要： Structure–property correlations were investigated for LaxCe1?xO2?δ (x = 0.05, 0.15) system (for both nanoparticles and ceramic). The nanoparticles were synthesized by the co-precipitation route and characterized for their structural, catalytic and visible light driven photocatalytic properties. Synthesised LaxCe1?xO2?δ nanopowders depicted phase purity with excellent compositional control as confirmed by various structural characterisation tools. The 15% La3+-doped ceria nanoparticles portrayed superior photocatalytic properties; complete degradation (99%) of the methylene blue dye was observed within 60 min of visible light irradiation under an alkaline medium. High density (> 96%) of the ceramics (sintered at 1580 °C for 2 h) confirmed promising sinterability of the synthesised powders. The ionic conductivities of the LaxCe1?xO2?δ ceramics increased with temperature and frequency owing to enhanced oxygen vacancies in the ceria matrix as a result of doping (of La3+-ions); a maximum conductivity of ~ 8.4 × 10?2 S cm?1 was obtained at 900 °C for the 15% La3+-doped ceria ceramics at 1 MHz frequency.
关键词： LaxCe1?xO2?δ,nanocrystals,photocatalytic properties,co-precipitation,ionic conductivity,bulk ceramics
更新于2025-09-10 09:29:36