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Flexible electronics are usually fabricated using stretchable or foldable materials, whereas these materials have no predominance in miniaturization of high-frequency flexible electronics because of low permittivity. In effort to scale down dimensions of electronic devices, the use of ferrite ceramic/polymer matrix may offer superiority over conventional dielectric ceramics. Polydimethylsiloxane (PDMS), which exhibits high transparency and stretchability, has emerged as functional or substrate material for high-performance devices, such as RF antenna. Here, to improve high-frequency magnetic-dielectric properties of PDMS matrix, a high-performance LiZnTiMn (LZTM) ferrite is synthesized and added in the PDMS matrix. We demonstrate, through magnetic, dielectric spectra and elasticity test, a flexible 3L/PDMS composites (f = 1.0 GHz, μr = 2.87, er = 6.51, tanδμ = 0.55, tanδe = 0.015) was prepared by using mechanical mixing method. Moreover, the elastic modulus and miniaturization factor (n) of the flexible composite are 16.78 MPa and 4.32@1.0 GHz, respectively. The present results provide a reference connecting flexible electronic and RF devices, and offer experience on how to enhance high-frequency performance of polymer-matrix based on ceramic material.

Several models involving spray atomization, wall impingement, evaporation and urea pyrolysis were built through a commercial code to study the influence of parameters of Urea Selective Catalytic Reduction (Urea –SCR) injection system on critical performances at low exhaust temperatures. The spray development, NH3 concentration distribution and wall film thickness have been studied. Results suggest that the wall impingement of the Urea Water Solution (UWS) is more at the temperature of 180°C than at 430°C. Lower temperatures tend to hinder evaporation and pyrolysis. NH3 concentration is uneven at low temperatures and the fuel film generated on the wall is also incomplete. Low temperatures could help injection system with a tilting nozzle raise its injection pressure and accelerate the evaporation and pyrolysis of the droplets. The distribution of spray impingement, however, is narrower and the fuel film thickness on the wall is increased. Smaller injection angle made it easier to expel gas stream and the droplets would then follow the direction of the gas stream. The droplets distribution is therefore more uniform and the spray wall-impingement reduced.

Broadband photodetection from visible to infrared spectrum region are of increasing importance in military and civilian applications. Recently, mercury telluride (HgTe) colloidal quantum dots(CQDs) have gradually become an attractive alternative for traditional narrow band gap semiconductors owing to their tunable spectral response. In this paper, HgTe QDs have been successfully synthesized. By simply spin-coating and ligand exchange treatment, the broadband photodetection based on HgTe CQDs up to near Infrared can be achieved.

The high-crystalline indium oxide (In2O3) nanowires were deposited by chemical vapor deposition (CVD) method on Si (111) substrates using C and In2O3 powders as the raw materials. The morphology, microstructures and the valences analysis of In2O3 nanowires were characterized by XRD, SEM, EDS, XPS and TEM techniques. The length and density of In2O3 nanowires can be effectively controlled by adjusting the experimental parameters. The optimal growth condition is obtained, namely the Au catalyst thickness of 12 nm, growth temperature of 1050 °C and Ar flow rate of 200 sccm. The cubic bixbyite structure as pure In2O3 (space group I a 3 ¯ ) as well as large amounts of oxygen vacancies can be observed in the deposited In2O3 nanowires. The photoluminescence (PL) spectrum shows an ultraviolet emission peak located at 390.6 nm and two luminescence peaks located at 423.6 nm and 436.5 nm, which can be attributed to the near-band-edge emission and the presence of oxygen vacancy defects in the In2O3 nanowires, respectively.

Weak absorption remains a vital factor that limits the application of two-dimensional (2D) materials due to the atomic thickness of those materials. In this work, a direct chemical vapor deposition (CVD) process was applied to achieve 2D MoS2 encapsulation onto the silicon nanopillar array substrate (NPAS). Single-layer 2D MoS2 monocrystal sheets were obtained, and the percentage of the encapsulated surface of NPAS was up to 80%. The reflection and transmittance of incident light of our 2D MoS2-encapsulated silicon substrate within visible to shortwave infrared were significantly reduced compared with the counterpart planar silicon substrate, leading to effective light trapping in NPAS. The proposed method provides a method of conformal deposition upon NPAS that combines the advantages of both 2D MoS2 and its substrate. Furthermore, the method is feasible and low-cost, providing a promising process for high-performance optoelectronic device development.

The effects of supercritical CO2 (scCO2) on polymer chains’ mobility and graphene nanoplatelets (GNPs) exfoliation and distribution in a microcellular foaming process are investigated by the molecular dynamics (MD) simulations and experiments. The results of MD simulations and visualization analysis confirm that the synergistic effect of scCO2 molecules and polystyrene (PS) chains is beneficial for them to penetrate into the interlayer of GNPs during the scCO2 treatment at high saturation pressure. The scanning electron microscope images show that some cells exist in the interlayer of GNPs in the foam fabricated in the highest saturation pressure and shortest depressurization time. With foaming in different depressurization time, the growing cells facilitate the movement of GNPs after their exfoliation, leading to alignment around the cells. As compared to large diameter GNPs, the GNPs with small diameter rearrange easily and distribute more homogeneously due to lower resistance of GNPs’ movement.

Polyvinyl acetate (PVA) adhesive is one of the most common types of adhesives has been used in the wood industry for decades. However, many drawbacks are still associated with this adhesive includi...

Quickly switching among different states (levels) is crucial for reconfigurable metamaterials and devices. In this study, the dynamics of establishment and transformation of five amorphous or near-amorphous intermediate states with obvious optical contrasts on Ge2Sb2Te5 phase-change thin films driven by ultrashort laser pulses were investigated using real-time reflectivity measurements. The reversible coding-recoding among the five optical levels was realized by using single-shot picosecond laser pulses with designed fluences. The optical constants, crystalline states and surface morphologies before and after ultrafast multi-level coding were also compared and analyzed. These results may lay a foundation for the further design and application of dynamically reconfigurable optical/photonic devices.

Hierarchically porous SiO2/C hollow microspheres (HPSCHMs) were synthesized by a hydrothermal and NaOH-etching combined route. The adsorption performance of the prepared HPSCHMs was investigated to remove Congo Red (CR) in aqueous solution. The results show that the synthesized composite possesses a hollow microspherical structure with hierarchical pores and a diameter of about 100–200 nm, and its surface area is up to 1154 m2 g−1. This material exhibits a remarkable adsorption performance for CR in solution, and its maximum adsorption amount for CR can reach up to 2512 mg g−1. It shows faster adsorption and much higher adsorption capacity than the commercial AC and γ-Al2O3 samples under the same conditions. The studies of the kinetics and thermodynamics indicate that the adsorption of CR on the PHSCHM sample obeys the pseudo-second order model well and belongs to physisorption. The adsorption activation energy is about 7.72 kJ mol−1. In view of the hierarchically meso–macroporous structure, large surface area and pore volume, the HPSCHM material could be a promising adsorbent for removal of pollutants, and it could also be used as a catalyst support.

The carrier gas flow field plays a vital role in the chemical vapor deposition (CVD) process of two dimensional (2D) MoS2 crystal, which was studied by simulations and experiments. Different carrier gas flow fields were studied by utilizing three types of precursor carrier which affected the local gas flow field significantly. The experiment results showed that the appropriate precursor vapor concentration could be achieved by local carrier gas flow field conditioning, resulting in single 2D MoS2 crystals of a large size and a high coating rate of 2D MoS2 crystal on the target substrate surface. The carrier gas flow also contributed to the growth of the 2D MoS2 crystal when it flew towards the target surface. The size of deposited single 2D MoS2 crystal reached tens of micrometers and a few layers of 2D MoS2 crystal were characterized and confirmed.

In this study, doping of Sb 2 Te 3 with silicon carbide has been proposed to enhance the optical and electrical properties of Sb 2 Te 3 . The silicon carbide-doped Sb 2 Te 3 (Sb 2 Te 3 -SiC)-based phase change memory cell can be triggered by a 10 ns electric pulse, indicating its excellent electrical properties. Furthermore, femtosecond pulses are used to study the reversible phase transition processes. The large reflectivity ratio of Sb 2 Te 3 -SiC is beneficial for achieving distinguishable logical states in optical applications. X-ray diffraction and transmission electron microscopy results show the SiC doping plays an important role in refining the grain size of Sb 2 Te 3 , producing smaller grain.

The crystallization process of Cr-doped Sb2Te thin films induced by repeated femtosecond laser pulses was studied systematically. The threshold effects and corresponding mechanism were comprehensively analyzed by real-time reflectivity measurements, optical microscopic imaging, and Raman scattering spectra. It was found that by doping the appropriate content of Cr into Sb2Te thin films, improved optical-thermal properties could be obtained, even in ultrafast crystallization processes.

Sn 1-x Fe x O 2 (x = 0, 0.023, 0.042 and 0.075) films were prepared by radio frequency magnetron sputtering. X-ray diffraction shows that Fe doping does not alter the tetragonal rutile structure of SnO 2 . X-ray absorption fine structure (XAFS) characterization shows that no Fe metal clusters or secondary phases are formed and that Fe 2+ and Fe 3+ coexist and substitute the Sn sites with oxygen vacancies to compensate charge nonequilibrium in the Fe-doped SnO 2 films. Fe 2p and asymmetric O 1s XPS spectra further verify the existence of Fe 2+ /Fe 3+ , lattice oxygen (Sn O band) and anionic vacancies. The room temperature ferromagnetism of the films has a strong dependence on Fe-doping level. The saturation magnetization increases with increasing the Fe doping level, whereas the carrier concentration decrease. Which implies that the ferromagnetism is not mediated by carriers. The bound magnetic polarons resulted from the oxygen vacancies play a key role in the observed room temperature ferromagnetism.

Promoting grain growth and optimizing microstructure are valid strategies for enhancing gyromagnetic and microwave dielectric properties of low-temperature sintered ferrite materials. Here, a modified low-temperature sintering technique was attempted for the synthesis of LiZnTi ferrites that have compact microstructure and improved performances. Trace amounts of CuO-Bi2O3 mixtures (0.50 wt%) were adopted as sintering additives to promote grain growth and to reduce the sintering temperature. Meanwhile, Li0.42Zn0.27Ti0.11Fe2.2O4 nanoparticles (∼21.9 nm) were synthesized using a sol-gel auto-combustion method and were used to optimize the microstructure and to restrain abnormal grain growth. XRD Rietveld refinement and SEM images revealed that uniform and dense LiZnTi ferrites with single-phase spinel structure were obtained. Results demonstrated that co-doping of Li0.42Zn0.27Ti0.11Fe2.2O4 nanoparticles and CuO-Bi2O3 mixtures allows low-temperature sintering (900 °C) to be achieved and also promotes grain growth and densification. In particular, LiZnTi ferrites that were modified with 5.00 wt% Li0.42Zn0.27Ti0.11Fe2.2O4 nanoparticles and 0.50 wt% CuO-Bi2O3 sintering additives exhibited narrow ferromagnetic resonance linewidth (ΔH, ∼145 Oe) and low dielectric loss tangent (tanδe, ∼2.45 × 10−4) at ∼9.50 GHz, high saturation flux density (Bs, ∼364 mT), and high squareness ratio (Br/Bs, ∼0.89). Such a modified sintering technique at a low sintering temperature, as reported in this work, provides a reference for other advanced ferrites.

Two-dimensional material-based photodetectors (PDs) show great potential owing to unique optoelectronic characteristics and attract much attention in research. However, poor absorption of two-dimensional material remains a vital restriction. Responsivity improvement by applying Au nanoparticles (NPs) through surface plasmon (SP) is studied both in theory and simulation. The effect of size and NPs distribution density is analyzed concerning absorption promotion and fabrication feasibility. Both absorption spectrum and inner electric field are studied. A novel face-to-face PD is proposed that performs better in visible range. The results can be helpful in two-dimensional material PD design and fabrication where high responsivity is required.

With a bipolar pulse power, wear-resistant ceramic coatings with high micro-hardness were in-situ fabricated on 2A50 aluminum alloy using micro-arc oxidation method in silicate electrolyte. The effect of cathodic voltage on microstructure, phase structure, micro-hardness and wear properties was investigated by changing cathodic voltage from 0 to −200 V. The phase structure, microstructure, micro-hardness and wear resistance were determined by XRD, SEM, HVS-1000 Vicker's micro-hardness tester and tribology tester. The results show that the phase of the obtained coatings is mainly composed of γ-Al2O3. The coating consists of the inner dense layer and the outer loose layer. As the cathodic voltage increases, the quantity and size of the micro-pores in the coatings first decrease and then increase. Micro-arc oxidation can greatly strengthen 2A50 aluminum alloy, the micro-hardness increases from 75 HV0.5 to 1321 HV0.5 after a micro-arc oxidation under a cathodic voltage of −100 V. The friction coefficient of the ceramic coatings are in the range of 0.35–0.55, and the coating obtained under −100 V exhibits the best wear resistance. The wear mechanism is deduced to be the combination of abrasive and adhesive wear.

[EN] The early stage spray characteristics have a great impact on the secondary atomization progress, and thus affect the engine combustion and emission performances. The experimental investigation of the early stage spray behaviors with biodiesel and diesel was carried out by employing a laser-based Mie-scattering method. The results show that the spray tip penetration for biodiesel is higher than that for diesel at the early stage spray under the same injection pressure. Moreover, the early stage spray tip penetration can be longer under high injection pressures for two fuels. Besides, the early stage spray cone angle for biodiesel is narrower than that for diesel, and the spray cone angle is especially higher than biodiesel by 25.8% after start of injection time of 0.01ms. Furthermore, under the same injection condition, the difference of early stage spray area between diesel and biodiesel is not obvious, while the spray volume for biodiesel is larger than that for diesel, and also the spray volume can be enlarged by increasing injection pressure for both fuels., This work was supported by the contribution of China postdoctoral fund projects [grant number2013M530236]; The projects of ‘Six talent peak’ [grant number 2014-ZBZZ-014]; Research start-up found projects of Jiangsu university [grant number 13JDG104]; Natural Science Foundation of Jiangsu Province of China [grant number BK20150520]；The Priority Academic Program Development of Jiangsu Higher Education Institutions [PAPD]

Silicon carbide/copper (SiC/Cu) ultrathin multilayer films were deposited on Si substrates by alternating the use of radio-frequency and direct current magnetron sputtering. It was found that the SiC layers possess an amorphous structure and Cu is incorporated into the SiC layers. The films have a p-type semiconductor characteristic, room-temperature ferromagnetic behavior, and negative magnetoresistance. A carrier concentration of up to 2.12 × 1020 and a saturation magnetization of up to 12.14 emu/cm3 are obtained, and Mott variable range hopping mainly dominates the conduction mechanism of the films. The theoretical fitting for the experimental magnetoresistance curves and the theoretical calculation of the density of states of Cu-doped SiC indicate that the ferromagnetism of the films originates from a carrier-mediated p–d exchange interaction.