•ZnFe2O4 nano-powder was prepared by co-precipitation assisted hydrothermal process.•Resistive switching memory device with Ag/CZFO/Au/Si structure was prepared.•Cu doping can obviously affect the bipolar resistive switching memory characteristics.•Cu ions assisted conductive filament is suggested to explain the change of memory behaviors.Resistive random access memory (RRAM) has been developing as a most promising non-volatile memory in the current memory technology. In this work, ZnFe2O4 (ZFO) nano powder were firstly prepared by co-precipitation assisted hydrothermal process. Further, the resistive switching memory devices with Ag/Cu doped ZnFe2O4 (CZFO)/Au/Si and Ag/ZFO/Au/Si structures grown on silicon (Si) substrate were prepared by radio frequency magnetron sputtering, and their memory behaviors were contrastively investigated. It is observed the Cu doping can obviously affect the bipolar resistive switching memory characteristics. Thus a model concerning the formation and rupture of Cu ions assisted conductive filament inside the CZFO layer is suggested to explain the change of memory behaviors. These works provide a foundation for exploring the memory application of multifunctional material and further regulate their nonvolatile memory behaviors.

•Pectin was firstly extracted from dried orange peel.•A memory device with Ag/Pectin/FTO structure was prepared.•The device exhibits superior resistive switching memory characteristics.•The conductive filament model is suggested to explain the memory behavior.In this work, pectin, a by-product has not been recycled sustainably, is introduced as an insulator to fabricate a novel organic resistive switching memory devices with Ag/Pectin/FTO structure for the first time. The device exhibits superior switching endurance accompanied by an OFF/ON resistance ratio (storage density window) of ∼450. This work reveals for the first time that pectin from fruit peel is a promising material for nonvolatile memory applications.Figure optionsDownload full-size imageDownload high-quality image (309 K)Download as PowerPoint slide

•Single phase CZTSe thin films have been deposited by RF sputtering of a single quaternary target, followed by a post-selenization.•Effect of deposition and selenization temperature on the properties of RF sputtered CZTSe layer were discussed.•CZTSe absorber layer with obvious photoconductivity response shows better junction property.Cu2ZnSnSe4 (CZTSe) thin films were deposited by RF sputtering method at different substrate temperatures, followed by an annealing step in SnSe2. It was found that the substrate temperature significantly affected phase structure and surface morphology of the precursor films. The annealed films show better crystallinity than the precursors. Single kesterite CZTSe phase was observed when the annealing temperature was below 505 °C. No photoconductive response was observed for precursor film, whereas the annealed films showed obvious photo-response under illumination. The film annealed at 480 °C shows the best photoconductivity, as a result of low carrier concentration (8.2 × 1014 cm−3) and high mobility (26.4 cm2·v−1·s−1). The Mo/CZTSe (annealed at 480 °C)/CdS/Au diode shows obvious rectification character. By using optimized CZTSe film, CZTSe solar cell was fabricated, and it showed power conversion efficiency of 0.34% with relatively high open circuit voltage of 350 mV. This work provides a way to modulate the structure and property of CZTSe film deposited by sputtering technique for fabricating solar cells.

•The MoSe2 nanosheets with nano-size were prepared by hydrothermal method.•The magnetism of MoSe2 nanosheets is strengthened by the decrease of temperature.•Temperature can regulate the memristor memory behavior of Ag/MoSe2/Ti device.•This work reveals the potential multifunctional applications of MoSe2 nanosheets.In this work, the MoSe2 nanosheets were firstly prepared by hydrothermal method. We found the magnetism of MoSe2 nanosheets obviously enhance with the decrease of temperature. Further, we fabricated a memristor using as-prepared MoSe2 nanosheets, and observed temperature can regulate the memristor memory behavior of the device. In a word, this work reveals the potential multifunctional applications of MoSe2 nanosheets with magnetism and memristive memory effects in future device technology.Download high-res image (102KB)Download full-size image

•The mechanism of MoS2 film based resistive switching device has been investigated.•The Ag/MoS2/Ti/Si device represents an outstanding memory behavior.•This work reveals that Ag filaments can be easily formed by redox process in MoS2 film.In this work, the resistive switching mechanism of metal/MoS2/Ti/Si devices with different metal acts top electrode materials have been investigated. The device represents an outstanding memory behavior with larger storage window when using Ag acts top electrode. This work reveals that Ag filaments can be easily formed by redox process in MoS2 film.Download high-res image (144KB)Download full-size image

•Biaxially textured YBa2Cu3O7-x + xYBiO3 composite films were firstly prepared.•The used method is fluorine-free polymer-assisted chemical solution deposition.•Influence of YBiO3-doping on the superconducting properties was investigated.Biaxially textured YBa2Cu3O7−x+xYBiO3 (x=0, 2.0, 5.0 and 10.0 wt%) composite films were firstly prepared on (00l) LaAlO3 substrate by self-developed non-fluorine polymer-assisted chemical solution deposition (PA-CSD). The growth orientation and the microstructure of YBa2Cu3O7−x+xYBiO3 films were characterized by X-ray diffraction (XRD) and environmental scanning electron microscope (SEM). Both the electrical transport and magnetization methods were used to measure the superconducting performance of the films. The surface density and smoothness of the doped YBa2Cu3O7−x films have been improved compared with that of the pure film. It is shown that YBiO3-doping lowers the superconductivity of YBa2Cu3O7−x films. The possible reasons are discussed in detail.

•Gd2Zr2O7 buffer layer with a thickness of about 300 nm for coated conductor were prepared.•The used method is a newly developed polymer-assisted chemical solution deposition.•YBCO has been deposited on Gd2Zr2O7/Y2O3/NiW exhibited a Jc (77 K, 0 T)=1.5 MA/cm2.Gd2Zr2O7 (GZO) buffer layers with a thickness of about 300 nm have been directly deposited on bi-axially textured Ni-5at%W (NiW) alloy substrate and the Y2O3 buffered NiW substrate by a newly developed polymer-assisted chemical solution deposition (PA-CSD) method. The solution prepared from metal nitrate precursor has been achieved by a simple, low cost, and effective method. The Y2O3 thin film was deposited as the seed layer by dc reactive sputtering technique. The films have been studied with X-ray diffraction (XRD) and AFM analyses. It is found that only GZO buffer layer on Y2O3/NiW can be grown with highly c-axis oriented. Highly epitaxial 500-nm-thick YBa2Cu3O7−x (YBCO) thin film, deposited on GZO/Y2O3/NiW, reaches a maximum self-field critical current density (Jc) of 1.5 MA/cm2 at 77 K the possible reasons are discussed in detail.

•SmBa2Cu3O7−z films have been prepared by self-developed polymer-assisted chemical solution deposition method.•The chemical solution deposition method is fluorine-free.•Four different metal cation concentrations (MCCs) were applied in the synthesis of coating solutions.•Film quality can be significantly improved by adjusting the MCCs.•The film with MCC of 1.0 mol/L has Tc of 91.2 K and Jc (0T, 77 K) above 1 MA/cm2.SmBa2Cu3O7−z (SmBCO) films with different metal cation concentrations (MCCs) were prepared on (00l) LaAlO3 substrate by self-developed non-fluorine chemical solution deposition (CSD) method. The influence of MCC on structure and performance of SmBCO films was investigated. The film with MCC of 1.0 mol/L shows better c-axis texture and smoother as well as denser surface microstructure than other films. With increasing the MCC, the superconducting transition temperature (Tc) of the films has a peak value of 91.2 K at MCC of 1.0 mol/L. And the films with MCC of 0.8 mol/L and 1.0 mol/L show higher current carrying capabilities in the magnetic fields according to the Jc−H behaviors.

The structure and magnetic phase diagram of the newly discovered Ir-doped SmOFeAs superconductor have been investigated by using a spin generalized gradient approximation SGGA + U method. It was found that iridium doping strengthened interlayer coupling between the [FeAs] and [SmO] layers as well as the delocalized electronic distribution of Fe orbitals. The parent compound SmOFeAs showed a metal–insulator transition with a Mott gap of 1.13 eV when considering an on-site energy of 4.0 eV on Fe 3dd shells. By introducing electrons from iridium, the SmOFe1−xIrxAs system was led to a change from the antiferromagnetic state of Fe-spins with stripe-type into a nonmagnetic state with its superconductivity coexisting with the SDW state.Highlights► Iiridium doping strengthens interlayer coupling between the FeAs and SmO layers. ► Iiridium doping delocalizes electron of Fe orbital in SmOFeAs. ► SmOFe1−xIrxAs shows a metal–insulator transition with a Mott gap of 1.13 eV. ► SDW state may coexists with superconductivity in SmOFe1−xIrxAs system.

The effects of mercury doping on the superconductivity, crystal structure, and electronic structure have been investigated in Hg-doped BaPb0.75Bi0.25O3 (BaPb0.75−xHgxBi0.25O3, BPHBO) by magnetic measurement, powder X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS). At lower doping levels, the system is metallic and superconducting. However, the superconductivity is fully suppressed by Hg doping at x>0.25 and recovered with further increase in Hg content at x>0.3, showing a superconductivity reentrant phenomenon. XPS analysis reveals that BPHBO experiences dual metal–insulator transitions (MITs) at these two superconductivity points, which are accompanied by lattice distortions, suggesting that they may be driven by Peierls transitions. The first MIT may be a Mott-transition, while the second may be due to competition between the band filling effect and modification of the charge-disproportionate state.

A series of SmCoAsO1−xFx (with x=0, 0.05, 0.1, and 0.2) samples have been prepared by solid state reactions. X-ray powder diffraction proved that all samples can be indexed as a tetragonal ZrCuSiAs-type structure. A clear shrinkage of the lattice constants a and c with increasing F content indicated that F has been doped into the lattice. The magnetic and transport properties of the samples have been investigated. Parent SmCoAsO compound exhibited complicated magnetism including antiferromagnetism, ferromagnetism, and ferrimagnetism. For the fluorine doped samples, the antiferromagnetic Néel temperatures were almost independent of the F content and metamagnetic transitions were observed below antiferromagnetic Néel temperatures. With increasing F content, high temperature (below 142 K) ferrimagnetic state gradually changed to ferromagnetic state. In the resistivity result, metallic conduction in the region of 2–300 K and Fermi liquid behavior at low temperatures were shown in all samples. Transport properties at applied magnetic fields showed anomalies at low temperatures.

A series of the SmFeAsO1−xFx and GdFeAsO1−xFx (x=0.05, 0.1, 0.15, 0.2, 0.25) samples have been prepared using nano-scaled ReF3 as the fluorine resource at a relatively low temperature. The samples have been sintered at 1100 and 1120 °C for SmFeAsO1−xFx and GdFeAsO1−xFx, respectively. These temperatures are at least 50–60° lower than other previous reports. All of the so-prepared samples possess a tetragonal ZrCuSiAs-type structure. Dramatically supression of the lattice parameters and increase in Tc proved that this low temperature process was more effective to introduce fluorine into REFeAsO. Superconducting transition appeared at 39.5 K for SmFeAsO1−xFx with x=0.05 and at 22 K for GdFeAsO1−xFx with x=0.1. The highest Tc was detected to be 54 K in SmFeAsO0.8F0.2 and 40.2 K in GdFeAsO0.75F0.25. The use of the nano-scaled ReF3 compounds has improved the efficiency of the present low temperature method in synthesizing the fluorine-doped iron-based superconductors.

The 5d transition metal Ir is successfully doped for Fe in SmFeAsO to induce superconductivity with Tc = 16 K at a doping level of ∼15 atom %. Ir doping decreases the As−Fe−As bond angle, β; this behavior is different from the change in β for the system with doping charges in the charge-reservoir layers.

The structure and magnetic phase diagram of the newly discovered Ir-doped SmOFeAs superconductor have been investigated by using a spin generalized gradient approximation SGGA + U method. It was found that iridium doping strengthened interlayer coupling between the [FeAs] and [SmO] layers as well as the delocalized electronic distribution of Fe orbitals. The parent compound SmOFeAs showed a metal–insulator transition with a Mott gap of 1.13 eV when considering an on-site energy of 4.0 eV on Fe 3d shells. By introducing electrons from iridium, the SmOFe1−xIrxAs system was led to a change from the antiferromagnetic state of Fe-spins with stripe-type into a nonmagnetic state with its superconductivity coexisting with the SDW state.Highlights► Iiridium doping strengthens interlayer coupling between the FeAs and SmO layers. ► Iiridium doping delocalizes electron of Fe orbital in SmOFeAs. ► SmOFe1−xIrxAs shows a metal–insulator transition with a Mott gap of 1.13 eV. ► SDW state may coexists with superconductivity in SmOFe1−xIrxAs system.

•A simple sol-gel method was used to synthesize LTO and LTO-TiO2.•Butterfly wings are originally used as a bio-template to facilely synthesize 3D LTO-TiO2.•The templated LTO-TiO2 exhibits significantly improved specific capacity and rate capability.•The model of 3D nanostructure is suggested to explain the ion transport behaviors.A simple sol-gel method with butterfly as a biotemplate to prepare Li4Ti5O12-TiO2 (LTO-TiO2) nanostructures is presented in this study. Results show that the LTO-TiO2 has a periodical 3-dimension (3D) nanostructure, and delivers a high reversible capacity of 169 mAh/g and nearly 100% capacity retention over 80 charge-discharge cycles. Furthermore, LTO-TiO2 nanostructures exhibit an excellent rate capability of 56 mAh/g at 20 C. It is believed that the high performance of the anode materials can be attributed to the high surface area and perfect electron transport channels of 3D periodical nanostructures. We firmly believe that this work hold great promise for providing a perfect reference for artificially synthesized micro-nanostructure materials.

Nanopolycrtstalline La2/3Sr1/3MnO3 ceramics were prepared using nanosized precursor powders. Highly nonlinear current–voltage characteristics were observed at room temperature and low temperature. The nonlinearity coefficient is in the range of 1.15–53.5. The electroresistance (ER) and magnetoresistance (MR) effects have been investigated. The magnetoresistance of all the samples shows strong dependence on sintering temperature. Magnetoresistance decreases with increasing temperature.

A series of La0.84-1.5xPrSr0.16+1.5xCu1-xMnxO4 (x=0, 0.05, 0.10, 0.15, 0.20, 0.25, and 0.5) and LaPr0.88+1.5yCe0.12-1.5yCu1-yMnyO4 (y=0, 0.04, 0.08, 0.10, 0.15, 0.20, and 0.3) were synthesized by solid-state reaction and studied by X-ray diffraction, electric transport property, and magnetic measurements. The structural distortion, superconductivity, and magnetism of the samples caused by Mn doping were examined and analyzed. An unusual behavior of superconductivity suppression by Mn doping as well as the coexistence of ferromagnetism and superconductivity is observed.

MgB2 bulks doped with Fe and Fe2O3 nanowires are prepared by hybridized diffusion method. The doping effect on superconductivity transition temperature, Tc, critical current density Jc, and flux pinning behavior have been studied. It is found that both Tc and Jc of MgB2 show quite different features for these two kinds of nanowires. Fe2O3 nanowires significantly suppress both Tc and Jc of MgB2, whereas Fe nanowires do improve the flux pining behavior of MgB2 although the Tc is slightly suppressed.

•Recent progress on the long coated conductors fabrication by F-free CSD method is presented.•Single buffer and partial-melting technology and slot-die coating methods have been developed.•Reel-to-reel facilities for continuous process have been achieved.Recent progress on the fabrication of long high-Tc superconducting coated conductors with a fluorine-free chemical solution deposition (CSD) method is presented. Developments including such novel methods as single buffer technology, partial-melting process on YBa2Cu3O7 (YBCO), slot-die coating and drying; reel-to-reel facilities for continuous process have been achieved in the effort on high-Tc superconducting coated conductors at SWJTU, which form a comprehensive technology to fabricate long coated tapes with high performances.

•Pure and Co-doped YBCO films were prepared by newly-developed chemical method.•The doped films have much denser and smoother surface microstructures.•Significantly enhanced fux-pinning properties have been obtained for dilute Co-doped flm.Pure and cobalt-doped superconducting YBa2Cu3O7−z (YBCO) films were prepared on (0 0 l) LaAlO3 substrate by a newly developed polymer-assisted metal organic deposition method. The cobalt-doped YBCO films display much denser and smoother surface microstructures and the superconducting transition temperature Tc spans a small range of 1.7 K with the doping levels. Significantly enhanced flux-pinning properties have been obtained for dilute cobalt-doped film. This may be attributed to the good grain connections and the effective flux pinning centers introduced by cobalt doping.