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A novel nacre-like flame-retardant paper based on graphene oxide (GO), and phytic acid (PTA) is fabricated via evaporation-induced self-assembly. This facile method is time saving and low energy consuming. A facile approach is proposed to improve thermal oxidative stability of GO paper by in situ phosphorus doping during flame exposure. Then fire-alarm system is designed based on the high-temperature thermal reduction characteristic of GO. The GO paper functionalized with PTA (GO-PTA) can provide ultrasensitive, reliable and longtime fire early-warning signal. Fire alarm can be triggered at approximately 0.50 s when GO-PTA samples are attacked by fire. Phosphorus atoms are in situ doped into graphene layers during fire exposure, endowing GO-PTA paper with outstanding thermal oxidative stability, and thus alarm duration time of GO is greatly improved. The work develops advanced fire detection and early-warning sensors that provide reliable and continuous signals, which provide more available time for fire evacuation.

Made available in DSpace on 2019-10-06T17:04:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Development and application of a new, simple, inexpensive, and eco-friendly method is presented for the quantification of bumetanide in human urine samples for the detection of doping in sports. The method involves the use of a paper platform and digital image detection and is based on the reaction between bumetanide, p-dimethylaminocinnamaldehyde (p-DAC), and HCl in a methanolic medium, yielding a colored compound in a delimited area on a qualitative filter paper. The concentrations of p-DAC and HCl were optimized by a chemometric experimental design. After the addition of the reagents to the paper, digital images were obtained by scanning in a multifunctional printer and analyzed using the RGB pattern. The linear bumetanide concentration range was 6.90 × 10 −5 –1.37 × 10 −3 mol L −1 with R 2 = 0.993 and the limits of detection (LOD) and quantification (LOQ) were 3.60 × 10 −4 and 1.09 × 10 −4 mol L −1 , respectively. A SPE clean-up step for the samples were required to eliminate the interference of urinary urea. The recoveries obtained varied from 94% to 105%, indicating the absence of significant matrix effects or interferences in urine samples after clean-up step. The proposed method was successfully applied to the analysis of bumetanide in human urine samples. Instituto de Química Universidade Estadual Paulista “Júlio de Mesquita Filho” UNESP, R. Prof. Francisco Degni 55, P.O. Box 355 Instituto de Química Universidade Estadual Paulista “Júlio de Mesquita Filho” UNESP, R. Prof. Francisco Degni 55, P.O. Box 355 CAPES: 001 FAPESP: 2015/21733-1

In this work, a novel time-resolved ratiometric fluorescent probe based on dual lanthanide (Tb: terbium, and Eu: europium)-doped complexes (Tb/DPA@SiO2-Eu/GMP) has been designed for detecting anthrax biomarker (dipicolinic acid, DPA), a unique and major component of anthrax spores. In such complexes-based probe, Tb/DPA@SiO2 can serve as a stable reference signal with green fluorescence and Eu/GMP act as a sensitive response signal with red fluorescence for ratiometric fluorescent sensing DPA. Additionally, the probe exhibits long fluorescence lifetime, which can significantly reduce the autofluorescence interferences from biological samples by using time-resolved fluorescence measurement. More significantly, a paper-based visual sensor for DPA has been devised by using filter paper embedded with Tb/DPA@SiO2-Eu/GMP, and we have proved its utility for fluorescent detection of DPA, in which only a handheld UV lamp is used. In the presence of DPA, the paper-based visual sensor, illuminated by a handheld UV lamp, would result in an obvious fluorescence color change from green to red, which can be easily observed with naked eyes. The paper-based visual sensor is stable, portable, disposable, cost-effective and easy-to-use. The feasibility of using a smartphone with easy-to-access color-scanning APP as the detection platform for quantitative scanometric assays has been also demonstrated by coupled with our proposed paper-based visual sensor. This work unveils an effective method for accurate, sensitive and selective monitoring anthrax biomarker with backgroud-free and self-calibrating properties.

The effects of doping of ZnO and Nb2O5 solids with Fe2O3 (1.4 wt%) and Ag2O (1.4 wt%) on its surface and catalytic properties were investigated, as well as its photocatalytic performance on the degradation of a pulp and paper wastewater (PPW). The catalysts were characterized by XRD, SEM, photoacoustic spectroscopy (PAS), NH3-TPD and textural analysis. The results obtained revealed that Fe2O3 doping of Nb2O5 conducted at 500 °C resulted in an increase of about 116% for SBET while Ag2O treatment exerted a decrease of 33% for SBET of the doped adsorbents. Doping ZnO with Fe2O3 or Ag2O led to an increase of 80% for SBET. Iron and silver doping also led to a decrease in band gap energy of at least 6%. The addition of 1.4 wt% Ag2O on ZnO followed by calcination at 500 °C resulted in an increase of 11% in the value of the reaction rate constant (kap) for COD reduction under UV radiation. The treatment of Nb2O5 with 1.4 wt% Ag2O increased by a factor of 2.04 the value of kap for the reaction taking place under VIS radiation. The catalysts partially reduced the organic load and the real colour of the wastewater, allowing the achievement of the specifications for release into rivers, so photocatalysis could be an alternative for pulp and paper wastewater final polishing.

My comments concern the significant error in the crystallographic part of the commented paper. It was discovered that the studied crystals are of sillenite type and the correct formula should be Bi25FeO39:Ni,Ti instead of BiFeO3. Moreover, the type of unit cell is not correct. Due to the doping the new type of unit cell, previously unknown, was proposed for such crystals. It was found that the studied sample contains two slightly different phases of the sillenite type. The actual chemical composition of the studied crystals is not known.

My comments concern the sever error in the crystallographic part of the commented paper. It was found that the studied crystal is of the sillenite type and the correct formula should be Bi25FeO39:Cd,Ti instead of some kind of solid solution based on BiFeO3. Moreover, the type of unit cell is not correct. Due to the double doping the new type of unit cell, previously unknown, was proposed for such crystals. The actual chemical composition of the studied crystals is not known.

The scalable and controllable preparation of carbon nanomaterial-based scaffolds with superior electromagnetic interference (EMI) shielding properties in addition to being ultrathin, robust, lightweight, flexible, and foldable is a challenging task. However, commonly used techniques such as integrating conducting moieties and high-temperature annealing cannot simultaneously meet the demands of high specific shielding effectiveness (SSE), robustness, and flexibility. Here, we adopted a novel PDA reduction technique to integrate various functionalities, including a nitrogen doping source, extended reduction of GO, and a large accessible area to accommodate multiwall carbon nanotubes (MWCNTs). The prepared ultrathin PDA-rGO/CNT composite sheet exhibited a low density (0.26 g/cm3), high flexibility, and superior shielding effectiveness (SE) under a wide range of microwave frequencies (i.e., the X band and Ku band). The total shielding effectiveness (SET) reached 47.6 dB and 48.7 dB in the X band and Ku band, respectively, at a thickness of 82 µm and a high SSE; in particular, the SE/density reached a maximum value of 183.3 and 187.3 dB cm3/g, respectively, which are superior to those of previously reported studies. This comprehensive study revealed the synergistic effect of PDA doping and MWCNTs, resulting in excellent shielding properties. Hence, this superior SSE and flexibility makes ultrathin lightweight PDA-rGO/CNT composite sheets a suitable candidate for replacing metallic counterparts for foldable and wearable electronic components.

Exploring novel photoactive materials with high photoelectric conversion efficiency plays a crucial role in enhancing the analytical performance of paper-based photoelectrochemical (PEC) biosensor. SnO2, which possesses higher photostability and electron mobility, can be regarded as a promising photoactive material. Herein, paper-based one dimensional (1D) domed SnO2 nanotubes (NTs) have been developed with the template-consumption strategy. What’s more, their growth mechanism has also been proposed based on the controllable experiments. At first, the paper-based 1D ZnO nanorods (NRs) as the typical amphoteric oxide are prepared and serve as the sacrifice templates which can be etched by the generated alkaline environment during the formation of SnO2. At a certain stage, all the ZnO NRs can be completely etched by controlling the experimental conditions, resulting in the forming of vertically distributed hollow SnO2 NTs. Furthermore, the Sn self-doping strategy is also proposed to suppress the recombination of charge carriers and broaden the light response range by introducing the impurity energy levels. Profiting from such doping strategy, the prominent photocurrent signal is obtained compared with pure paper-based SnO2 NTs. Ultimately, an innovative visible light responsive paper-based Sn-doping SnO2-x NTs are developed and employed as the photoelectrode for the PEC biosensor using the alpha fetoprotein (AFP) as the model analyte. Under the optimal conditions, the ultrasensitive AFP sensing is realized with the linear range and detection limitation of 10 pg mL-1 to 200 ng mL-1 and 3.84 pg mL-1, respectively. This work provides a judiciously strategy for developing novel photoactive materials for paper-based PEC bioanalysis.

Compared to metallic materials for the use of heat exchanger, polymeric materials have been enjoyed superior advantages such as corrosion resistance, low density, fouling resistance, facile processing and low cost. Poly(vinylidene fluoride) (PVDF) is semi-crystalline thermoplastic polymer with excellent corrosion resistance, thermal and electrochemical stability. In order to improve its thermal conductivity, graphene/PVDF composites were prepared and studied in this paper. The graphene was doped in PVDF matrix for preparing graphene/PVDF composite membranes. In addition, electric field was applied for graphene alignment during membrane formation. The morphology, structure, thermal conductivity and tensile strength of the composite membranes before and after alignment were characterized and analyzed. The tensile strength and thermal conductivity of composite membranes were significant improved with the addition of graphene. This tendency was further enhanced by the application of electric field. When graphene content was 20 wt%, the thermal conductivity of the composite membrane was increased by 212% than that of pure PVDF and it was further enhanced to 226% after applying electric field. The maximum tensile strength was obtained when graphene content was 3 wt%. This study may be beneficial to further development of thermal conductive polymeric materials. Keywords: Poly(vinylidene fluoride), Graphene, Composite membranes, Thermal conductivity

Here we present a comprehensive investigation of novel composite layered structures based on graphene, molybdenum disulfide (MoS 2 ) monolayers and hexagonal zinc oxide (ZnO), which display promising optical and electronic properties for photovoltaic applications. Theoretical study of the atomic structure, optical and electronic properties of proposed ZnO/MoS 2 and G/MoS 2 /ZnO/G nanostructures were carried out. We show that making the G/MoS 2 /ZnO/G heterostructure leads to high doping ratio of graphene layers and zero band gap which allows a conclusion of the possibility of using such structures in photovoltaic applications, due to broad energetic region of high electronic density of states.

The pickling sludge produced from rolling process contains a large amount of Fe, Ca, Al as well as other metals. If these metals can be extracted and used, it will promote the recycling of pickling sludge. Herein, we proposed a two-step extraction method to extract Fe ions out from the pickling sludge, and then the extracted Fe was oxidized by H2O2 and prepared into Fe-containing coagulant in the presence of Na2HPO4 as stabilizer. The three main factors that affect the color removal efficiency and COD removal efficiency are identified as P:Fe ratio, H2O2 adding amount, and curing time. Results show that the optimal preparation conditions are: P:Fe = 0.05, H2O2 amount = 115%, and the curing time = 6 d, at which the color and COD removal efficiency reached 96.25% and 65.91%, respectively. The assessment of toxicity of the PPFC indicated that the content of harmful substances meets the thresholds in Chinese national standard GB141591-2016. The findings in this study are expected to provide new implications in treating different kinds of Fe-containing sludge.

The samples of polyvinylidene fluoride/trifluoroethylene with different amount of graphene oxide dopant 5, 10, 15, 20 and 25% were fabricated and their phase situation were estimated. Moreover the para–ferroelectric phase transition was studied using the dielectric spectroscopy technique. The results of dielectric measurements allowed to perform Cole–Cole analysis and to estimate the activation energy of the films. On the basis of these results the influence of graphene oxide dopant on structure and properties of polyvinylidene fluoride/trifluoroethylene was discussed.

Sonophotocatalysis (SPC) is considered to be one of the important wastewater treatment techniques and hence attracted the attention of researchers to eliminate recalcitrant hazardous organic pollutants from aqueous phase. In general, SPC refers to the integrated use of ultrasonic sound waves, ultraviolet radiation and the addition of a semiconductor material which functions as a photocatalyst. Current research has brought numerous improvements in the SPC based treatment by opting visible light irradiation, nanocomposite catalysts and numerous catalyst supports for better stability and performance. This review accomplishes a critical analysis with respect to the recent advancements. The efficiency of SPC based treatments has been analyzed by considering the individual methods i.e. sonolysis, photocatalysis, sonophotolysis, sono-ozone, photo-Fenton and sono-Fenton. Besides, the essential parameters such as solution temperature, concentrations of initial pollutant and catalyst, initial pH, dosages of Fenton’s reagent and hydrogen peroxide (H 2 O 2 ), ultrasonic power density, gas sparging, addition of radical scavenger, addition of carbon tetrachloride and methanol have been discussed with suggestions for the selection of optimum parameters. A higher synergistic pollutant removal rate has been reported during SPC treatment as compared to individual methods and the implementation of numerous doping materials and supports for the photocatalyst enhances the degradation rate of pollutants using DSPC under both visible and UV irradiation. Overall, SPC and DSPC based wastewater treatments are emerging as potential techniques as they provide effective solution in removing the recalcitrant organic pollutants and progressive research is expected to bring out superior treatment efficiency using these advanced technologies. Importance of this review The review has accomplished a thorough and a critical analysis of sonophotocatalysis (SPC) based on the recently published journals. Recent advancements in the doped sonophotocatalysis (DSPC) and the mechanisms behind synergistic enhancement in the pollutant degradation rate have been discussed with justifications. Besides, the possible future works are suggested for the advancements in sonophotocatalysis based treatment. This review will be beneficial for electing a SPC based method because of the accomplished sharp comparisons among the published results. The review includes current advancements of SPC based methods which aid for a low-cost and a large-scale wastewater treatment application.

Exploring highly active, durable and low-cost catalysts toward hydrogen evolution reaction (HER) holds a key to clean energy technologies. Heteroatoms-doped graphene-based materials are emerging as the most promising metal-free HER catalysts, but their catalytic activity remains largely unexplored. Herein, by rationally engineering the macroscopic architecture of graphene and its chemical/defective structures, we developed a three-dimensional (3D), N-doped, plasma-etched graphene (3DNG-P) as a highly active metal-free HER catalyst. The obtained 3DNG-P combined the merits of freestanding 3D porous architecture, high-level N-doping and plasma-induced enriched defects, resulting in a highly enhanced HER activity with a low overpotential of 128 mV at 10 mA cm −2 in acidic medium. Furthermore, the 3DNG-P displayed a favorable HER activity and stability over a wide pH range. The present study thus provides a new methodology for the design of graphene-based metal-free catalysts with high HER performance.

Aluminum doped ZnO nanoparticles (AZO-NPs)/graphene nanocomposites, with different Al concentrations, were successfully synthesized by a facile one-step solvothermal method at low temperature. SEM and TEM images of the prepared samples indicated that AZO-NPs have been grown and rather well distributed on the surface of graphene sheets. The average particle size of AZO-NPs was found to decrease with increasing Al concentration. The XRD analysis confirmed the formation of AZO-NPs/graphene nanocomposites with hexagonal wurtzite structure. The results of FT-IR and Raman spectroscopy showed that the oxygen-containing groups, which exist on the surface of the graphene oxide sheets, are removed and the graphene oxide is reduced to graphene during the synthesis procedure. Our results revealed that the simple low cost method used in this work is suitable for the synthesis of graphene-based semiconductor nanocomposites.

N-doped TiO2 nanowire/N-doped graphene (N–TiO2/NG) heterojunctions are fabricated by a simple hydrothermal method in a solution containing urea. In this hybrid structure, a three-dimensional hybrid photocatalyst was fabricated by using one-dimensional N-doped TiO2 nanowires penetrating through two-dimensional graphene nanosheets. Compared with TiO2 nanowire/graphene and N-doped TiO2 nanowire/graphene composites, the N–TiO2/NG heterostructures demonstrate a better photocatalytic performance for the degradation of methylene blue under visible light irradiations, as well as displaying a better recyclability. It is found that the nitrogen atoms originated from the decomposition of urea were not only entered into the lattice of TiO2 nanowires but also doped into the skeleton of graphene nanosheets. Results show that N doping expands the visible light absorption region of TiO2, and N-doped graphene additionally improves the separation and transportation of photogenerated electron–hole pairs plus generating a higher photocurrent, which plays a critical role for enhancing the photocatalytic activity.

Spherical iron oxide nanostructures (FexOy NPs) are obtained by laser ablation technique, which are formed primarily by α-hematite (α- Fe2O3), γ-hematite (γ-Fe2O3) and goethite (FeOOH) phases, the dimensions of which are among the 30-60 nm by using the Scanning Electronic Mycroscope (SEM) analysis. These were incorporated superficially on graphite microflakes (MFG, microflakes of graphite) and / or a few layers of graphene microflakes (FLG, few-layer graphene), through a thermal process, in order to observe their influence on the electro-optical properties on MFG and FLG, tested by Raman microspectroscopy, we detect a correlation of Raman shifts before and after doping. This is explained as a change in the dispersion of two phonons at the edges of the C-C chains forming the FLG against the formation of surface defects due to interaction with FexOy NPs after insertion. Finally, a study of the position, the FWHM, the ration between the intensities and the areas of the G and 2D bands was made in all samples with two Raman lasers (λ = 534 nm and 422 nm).

Density functional theory calculations were performed to study the photocatalytic properties of molybdenum disulfide/graphene composites by analyzing the structure, electronic properties and optical properties of molybdenum disulfide/graphene composites. Three typical structures of molybdenum disulfide considered in our work include pristine molybdenum disulfide and molybdenum disulfide with mononiobium doping. They were then composited with graphene, N-doped graphene and graphene with epoxy, respectively. The characteristics of these composites (MoS 2 /graphene, MoS 2 /N-G, MoS 2 /O-G and Nb–MoS 2 /N-G) including binding energies, charge transfer, projected density of states, electron density and optical properties were calculated and analyzed. The binding energies of between MoS 2 and graphene were related to the extent of charge transfer. The data of projected density of states, band structures and optical properties gave an explanation of the mechanism for significant photocatalytic activity of MoS 2 /N-doped graphene and Nb-doped MoS 2 /N-doped graphene composites.

Carbon materials doped with only one kind of C–N bonding configuration are a great outlook for studying doping effects on the electronic structure and electrical properties. Synthesis of nitrogen-doped few-layer graphene films on Cu foil is achieved by low pressure chemical vapor deposition (LPCVD). For investigation of nitrogen doped effect on structural, morphological and electrical properties of graphene the reactive gas was a mixture of CH 4 and NH 3 with the different ratio CH 4 and NH 3 by volume at the constant pressure of the growth chamber. The N-doped graphene (NG) samples were characterized by Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS). Also in this experiment, the I – V characteristic carried out for study of electrical property of N-doped graphene at different gases mixing ratio with keithley 2361 system. The Raman spectroscopy showed D, G and 2D bound in doped and undoped graphene while we find the intensity of the 2D peak decreases and D peak intensity increases with the increase in the percent of NH 3 in gas mixture. Likewise the presence of weak 2D band in all sample suggest that the produced samples are few layer graphene. SEM images showed dendritic-like morphology in undoped graphene and we observed that point like defect created among this morphology by increasing the nitrogen in synthesis process. The XPS results of sample with 25% NH 3 in gas mixture confirm the existence of nitrogen in doped graphene which indicates the nitrogen atoms doped in the graphene lattice are mainly in the form of pyridinic nitrogen. The study on electrical properties emphasized that the dependence of current with voltage for all samples was linear like behavior, and sample conductivity was decreased with increasing the percent of nitrogen in gas mixture. The results showed that nitrogen-doped graphene can be successfully synthesized and also chemical nitrogen doping can be change the electrical conductivity of the graphene.

article i nfo Chemical vapor deposition in a hot wall reactor is the most common technique for the production of large area single layer graphene. However, growth in this type of reactors is time consuming and the results are limited by the surface quality of the widely used catalytic metal foils as growth substrates. In this work we demonstrate the use of millimeter-thick Cu and Pt substrates for graphene growth via inductive magnetic heating, which allows for fast temperature ramps during heat up and cooling. Based on a detailed growth study, a two-step growth process resulting in continuous monolayer graphene films of high crystal quality with grain size of larger than 90 μm is established. An electrochemical transfer process is used to separate the graphene film from the metallic substrate, yielding excellent results in terms of defect density, doping and residual contamination. Back-gated graphene field-effect transistors fabricated on Si/SiO2 structures exhibit a high reproducibility with a peak mobility higher than 4000 cm 2 /Vs. The combination of the highly time efficient graphene growth and electrochemical transfer together with the reusability of the growth substrates and the possibility of applying novel surface pretreatments pave the way for the use of high qual- ity substrates in industrial applications.

We have used spatially resolved micro Raman spectroscopy to map the full width at half maximum (FWHM) of the graphene G-band and the 2D and G peak positions, for as-grown graphene on copper catalyst layers, for transferred CVD graphene and for micromechanically exfoliated graphene, in order to characterize the effects of a transfer process on graphene properties. Here we use the FWHM(G) as an indicator of the doping level of graphene, and the ratio of the shifts in the 2D and G bands as an indicator of strain. We find that the transfer process introduces an isotropic, spatially uniform, compressive strain in graphene, and increases the carrier concentration.

The effects of graphene and C coating modifications on electrochemical performance of silicon nanoparticle (SiNP)/graphene composite anode were investigated. Graphene with varying sheet sizes (238, 160 and 113 nm) were used as an anode material where a cycling performance dependence on the sheet size (edge sites and sheet disorder) was observed. Temperature-dependent N doping of graphene resulted in graphene with N (5.97% w/w) presenting three binding configurations: 72.1% pyridinic N, 22.4% pyrrolic N and 5.5% graphitic N. The nitrided graphene displayed improved cycling capacity and minimized performance decay, principally due to the pyridinic N. Galvanostatic cycling using increasing current density rates (500–2500 mA g −1 ) of SiNP composites with C coating/deposition showed improvements in both capacity retention and rate performance. A polyacrylonitrile (PAN)-based coating scheme was used to produce a N-containing (2.20%) C coating which displayed the best high performance improvements, attributable to the minimization of direct solid-electrolyte interphase (SEI) formation and improvement in the conduction path. Optimization of the methods to achieve the best modification characteristics might enable performance improvements that maximize the capabilities of the materials.

The interaction between hydrogen sulfite (H2S) and graphene was investigated by density functional theory calculations and nonequilibrium Green’s function formalism. The structural and electronic properties of H2S–graphene systems were studied by tuning the geometries of H2S molecule toward 2D nanosheets of pristine, defective and doped graphene. It was found that Ca, Co and Fe doped and defective graphene nanosheets show much higher affinities to H2S molecule in comparison to pristine graphene. The strong interactions between H2S and graphene nanosheets modified with transition metals can lead to dramatic changes to the electronic and magnetic properties of graphene. The electronic transport behaviors of Fe-doped graphene nanosheets indicate that the chemical sensors constructed with the materials could exhibit much higher sensitivity for detecting H2S gas, in comparison with that of devices made with pristine graphene. It is possible to design H2S chemical sensors with highly improved performances, using graphene nanosheets as sensing materials with appropriate metal dopants or defects. In addition, the graphene doped with Si absorbs H2S molecule through forming Si–S bond, compared to the weak physisorption of H2S molecule onto pristine and the B, N doped graphene.

High-efficiency leaching of valuable metals from nickeliferous laterite ore for preparation of functional materials is one of the most important high-value utilization pathways. In this paper, facile preparation of multi-metal spinel-type ferrites (MFe2O4) from saprolite laterite ore after pickling waste liquor leaching process was proposed. The effects of pickling waste liquor leaching parameters including acid concentration, leaching temperature and time, liquid–solid ratio and iron ion concentration on leaching efficiency for Fe, Ni, Mg, Mn and Co from saprolite laterite ore and the molar ratio (RFe/M) of iron ions to divalent metal ions such as Ni2+, Mn2+, Mg2+, etc. in the leach liquors were systematically investigated. After complete leaching, spinel-type ferrites were synthesized from leach liquors and the influence of RFe/M and pH value as well Zn ion doping on phase compositions, morphological structure and magnetic performance of as-synthesized samples were also characterized and analyzed. Under the optimized leaching conditions, the leaching efficiency of Ni, Co, Mn, Fe and Mg could reach 93.2%, 90.8%, 94.3%, 95.5% and 85.3%, respectively. With the concentration of iron ions in pickling waste liquors increasing from 60 to 160 g·L−1, the RFe/M value increases from 1.88 to 4.32. The pH values for synthesis of spinel-type ferrites with high purity from leach liquors with RFe/M of 1.85 and 2.04 are 8.0 and 11.0, respectively, and the saturation magnetization Ms values of as-synthesized ferrites increase gradually with the increasing of pH value. Zn ions in pickling waste liquors could be doped and fixed in spinel-type ferrites to improve Ms values of as-synthesized ferrites, and the Ms value could reach the highest as 58.6 emu·g−1 when Zn ions doping amount is 0.4. Value-added utilization of pickling waste liquor and saprolite laterite ore could be realized by the proposed process. This paper might provide theoretical and technical support for low-cost synthesis of spinel-type ferrites from polymetallic resources.

International audience; This feature article highlights the recent advances on the lanthanide-activated nanoparticles prepared by pulsed laser ablation in liquids (PLAL). In the past decade, rare-earths-activated nanoparticles have been recognized from various applications including lots of high-tech products, green technologies, bioimaging and medical utilization. To obtain inorganic nanoparticles with different morphologies and sizes, pulsed laser ablation in liquids is a green and versatile technique. In this paper, a survey of the nanoparticle's formation during the laser ablation in the liquids is first introduced. We focus on the control of the size and morphology through proper laser parameters, choice of the reaction solution and proper surfactants. In the last part of the paper, we successfully prepared persistent luminescent SrAl 2 O 4 : Eu 2+ , Dy 3+ by laser ablation in liquids and their optical features are investigated.

In this paper, a series of high performance near-infrared reflective pigments based on Bi3YO6 doped with Fe2O3 and Tb4O7 were prepared by high-temperature calcination method. The pigments were characterized by some analytic techniques, such as XRD, Particle size analyzer, SEM, EDS, UV–vis–NIR spectrophotometer, CIE L*a*b* (1976) color space and infrared thermal imaging. Experimental results showed that the Fe2O3 doping in Bi3YO6 could change the color from bright yellow to ochre red. The substitution of Tb (IV)-doped pigments changed the color to dark orange. The doping of Fe (III) and Tb (IV) contributed to enriching the color diversities of pigments. Among the synthesized pigments, Bi3-xFexYO6 and Bi3Y1-xTbxO6+δ displayed a disordered defective fluorite-type structure. The effect of doping Fe (III) and Tb (IV) reduced the near-infrared reflectance of the pigment. Excepting for Bi3-xFexYO6 (x = 0.8), the near infrared reflectance of some other pigments were higher than the China National standard (CNs). Chemical resistance tests showed that the pigments had excellent acid and alkali resistance. Finally, the application practical of traditional iron oxide yellow pigment and three prepared pigments, i.e., Bi3YO6, Bi3-xFexYO6 (x = 0.4) and Bi3Y1-xTbxO6+δ (x = 0.05) were studied and compared by infrared thermal imaging. The test results showed that Bi3YO6 still had a strong near-infrared reflection effect after being painted. Compared with traditional iron yellow pigment, Bi3YO6 could reduce the surface temperature of galvanized sheet by 20 °C under the illumination of infrared light. The series of Fe (III) and Tb (IV) doped pigments prepared in this paper have revealed some promising application values.

For a long time, rare-earth ion-doped phosphors have been widely used in temperature sensing because of their excellent light-emitting properties. However, most of the rare earth elements are relatively rare and expensive, so the transition group elements that are economical and easy to obtain have been favored by researchers. This paper presents a new type of phosphor doped with rare earth ion and transition metal for optical temperature measurement. In recent years, Mn4+-doped phosphors have attracted wide attention because of their strong deep red light-emitting properties. La2LiSbO6 provides a good host environment for Mn4+ and Eu3+ due to its unique crystal structure. In this paper, a series of La2LiSbO6 phosphors singly doped with Mn4+ and Eu3+, and co-doped with Eu3+/Mn4+ were synthesized. The crystal phases and optical properties of these materials were characterized and analyzed in detail. We specifically studied the temperature dependence of the fluorescence intensity of the optimized La2LiSbO6: Eu3+, Mn4+ phosphors at 303K–523K. The experimental results prove that the thermal responses of Mn4+ and Eu3+ are different. With increasing temperature, the thermal quenching of the Mn4+ fluorescence intensity is much faster than that of Eu3+, so the temperature characteristics can be explored by the fluorescence intensity ratio (FIR) of Eu3+ to Mn4+. At 523 K, its maximum relative sensitivity and maximum absolute sensitivity can reach 0.891% K−1 and 0.000264 K-1, respectively. Our experimental analysis shows that La2LiSbO6:Eu3+/Mn4+ phosphors have relatively high temperature sensitivity and have potential application prospects in the field of high temperature sensing.

This paper discuss a possibility for using a thin-film functional coating based on transparent conducting thin films of aluminum doped zinc oxide ( AZO ) as a heat-eliminating material on the surface of a spacecraft. The structure of the functional coating has been chosen taking into account the plasmonic properties of AZO and silver and represents the AZO slabs with embedded silver nanoparticles deposited on AZO layer and AZO slabs with embedded silver nanoparticles deposited on thin film fused quartz layer. The paper contains COMSOL finite element simulations of the scattering cross section for thermal radiation in the IR band in the case the investigated coating deposited on a reflective aluminum film, and absorption cross section in the near UV and visible spectral bands when the coating deposited on silicon solar panels. The calculations demonstrate an increase in the scattering cross-section in the spectral band of blackbody radiation by several orders of magnitude, with the maximum in the scattering spectrum of the AZO slabs/ AZO /Al structure corresponding to the maximum intensity of the blackbody thermal radiation, which has been heated to 100 °C in the case the lattice period of the AZO slabs is equal to the resonance wavelength for AZO . Also an increase in the absorption cross-section of AZO slabs/ AZO /Si structure in visible spectral band is observed corresponding to plasmon absorption of embedded silver nanoparticles.

Graphene-silicon (Gr-Si) Schottky barrier solar cells (SBSC) have experienced a significant improvement in cells’ efficiency from less than 2%–15.6% in a decade. So far, the record efficiency of 15.6% was achieved via a combination of techniques such as interface oxide passivation, chemical doping, anti-reflection coating and et al. In this paper, a particular attention is paid to recently developed techniques to passivate Gr-Si interface, resulting in a significantly reduced interface recombination and hence a better open circuit voltage (Voc) of the cells. Three methods: 1.dangling bonds termination; 2.insulator layer insertion; 3. hole transport layer insertion, are reported to be able to passivate the Gr-Si interface. We will introduce these three methods and their underlying mechanisms in turn in this paper and, at last, put forward our thoughts on further improving the Gr-Si interface passivation.

Doping metal element on One-dimension (1-D) nanostructure to improve the photoelectric properties of metallic oxides has been widely studied. In this paper, Magnesium (Mg) and Erbium (Er) ions were co-doped onto TiO2 nanorod arrays (NRAs) via a facile hydrothermal method and applied in perovskite solar cells (PSCs). The synthesized Er/Mg co-doped TiO2 NRAs was investigated by field emission-scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), UV–vis diffused reflectance and electrochemical impedance spectroscopy (EIS). Er/Mg co-doped TiO2 changed the band gap, which increases the charge injection efficiency. The EIS exhibited that the Er/Mg co-doped device has a higher recombination resistance than un-doped device, which enhances the open circuit voltage (Voc) of the solar cells. Simultaneously, UV–Vis absorption reflectance spectra show that the co-doped TiO2 NRAs enhance the light capture ability via absorbing infrared light and increase the short-circuit current (Jsc). The power conversion efficiency (PCE) of Er/Mg co-doped PSC device increased from 8.26% to 9.67%, which was 17% higher than that of the un-doped device. This paper opens a door to single-element doping or multi-element co-doping 1-D nanostructured materials for the improving the utilization of solar energy and the photoelectric conversion performance of PSCs.

Among all inorganic perovskite, CsPbI3 has the closest ideal bang gap for solar cells. However, the instability of metal halides hinders its commercial application. The doping of A-site organic cations might improve the stability of perovskite and also make the bandgap adjustable, thus enhance its photoelectric properties. In this paper, the structure stability, electronic structure and optical properties of CsPbI3 with five different organic cations (H3NNH2+, CH3NH3+, C3H6NH2+, CH3NH2CH3+, CH3CH2NH3+) partially alternative doping instead the A site cation have been studied by using the first principles within density functional theory. In order to get accurate description of the bandstructure information, different exchange–correlation functions, e. g. PBE, PBE + SOC and HSE were used to describe the calculated systems, our calculation results indicated that the PBE exchange–correlation function can describe the electronic properties of the systems very well in this paper. Formation energy calculation indicates that all the doping systems are thermally stable; and all the doped CsPbI3 show good tolerance factor according Goldschmidt rule. Among the five different doping systems, the bandgap of doped H3NNH2+ will decrease to 1.28 eV, while the bandstructure of other doped cations will widen the bandgap. The maximum bandgap increased to 1.65 eV with doping C3H6NH2+. However, all the band structures are mainly contributed by inorganic framework. The results suggest that the structure doped organic cations can be exited stably, and the band edge of the optical absorption spectrum will be redshifted. These properties can provide research ideas for the subsequent research of A-site doping organic cations.

Photoreversible color switching fabrics have attracted much interest by using plasmonic semiconductor-catalyzed systems with simultaneous high photocatalytic and photothermal effects, while such kinds of semiconductors are rarely reported. In this work, with ZnO as a model, we report the tuning of plasmonic performances of ZnO nanocrystals by doping various concentrations of indium ions through a solvothermal route. Indium doping not only confers size evolution but also incorporates ZnO lattices with a high concentration of free electrons that result in extended plasmonic photoabsorption, simultaneously achieving high photocatalytic and photothermal performances. The plasmonic In-doped ZnO nanocrystals, along with redox dyes, can be conveniently utilized for the design of a series of novel semiconductor-catalyzed color switching systems, including mono-color (red, green, blue) and multi-color switching (red, yellow, blue) systems, which rapidly respond to 365 nm light for photocatalytic discoloration and 980 nm light-induced photothermal heating for recoloration (in air). Furthermore, with methylcellulose as the polymer matrix, the plasmonic In-doped ZnO catalyzed systems can be further processed into switchable fabrics/papers, exhibiting excellent mono/multi-color response features. Based on the manipulation of the interactions between light and plasmonic semiconductor-catalyzed systems, the rewritable fabrics/papers exhibit a broad range of highly reversible photochromic features, showing great potential for application as advanced sensors and rewritable media.

Hematite (α-Fe2O3) is found to be one of the most promising photoanode materials used for the application in photoelectrochemical (PEC) water splitting due to its narrow band gap energy of 2.1 eV, which is capable to harness approximately 40% of the incident solar light. This paper reviews the state-of-the-art progress of the electrochemically synthesized pristine hematite photoanodes for PEC water splitting. The fundamental principles and mechanisms of anodic electrodeposition, metal anodization, cathodic electrodeposition and potential cycling/pulsed electrodeposition are elucidated in detail. Besides, the influence of electrodeposition and annealing treatment conditions are systematically reviewed; for examples, electrolyte precursor composition, temperature and pH, electrode substrate, applied potential, deposition time as well as annealing temperature, duration and atmosphere. Furthermore, the surface and interfacial modifications of hematite-based nanostructured photoanodes, including elemental doping, surface treatment and heterojunctions are elaborated and appraised. This review paper is concluded with a summary and some future prospects on the challenges and research direction in this cutting-edge research hotspot. It is anticipated that the present review can act as a guiding blueprint and providing design principles to the scientists and engineers on the advancement of hematite photoanodes in PEC water splitting to resolve the current energy- and environmental-related concerns.

The hardness and toughness of W-N coating deposited by conventional magnetron sputtering (CMS) usually cannot be improved simultaneously. In this paper, a nitrogen (N) doped approach using high ionized plasma assisted coating (HIPAC) technology was used to challenge the inversion relationship. Reference pure W coatings were also deposited using the same process parameters without nitrogen. The effect of N dopants on the microstructure, mechanical and tribological properties of N-doped W(N) coatings was systematically investigated by electron microscopic methods, indenter tests and ball-on-disc sliding tests. The results indicate that the W(N) coatings have higher hardness, better toughness, more compact surface and finer columnar crystallites compared to pure W coatings. The preferred orientation changes from (110) to (222) with introducing N dopants. No brittle W-N compounds are detected in W(N) coatings. TEM observations reveal that part of the N dopants in W(N) coatings exist as solute atoms in the α-W solid solution, and the others are aggregated as N-clusters. Hence W(N) coatings can get the ceramic hardness (~30 GPa) and retain the metallic toughness. Benefiting from the high hardness, good toughness and reduced friction coefficient (~0.42), the wear rate coefficient of W(N) coatings is one order of magnitude lower than W coatings. Compared to the reported C and B atoms doped W(C/B) coatings produced by CMS, the W(N) coatings deposited by HIPAC in this paper can give a competitive strategy to achieve better mechanical properties.

This paper aims to evaluate the effects of calcination temperature and manganese doping on optical properties and phase evolution of Mn-doped TiO2 pigments. The powders were prepared by the polymeric precursor method at Mn contents of 0, 1, 2 and 3 % and calcined at 600, 700 and 800 °C. The results demonstrated that crystalline powders were produced in all conditions evaluated. It was further noted that the samples calcined at 600 °C were composed of rutile and anatase TiO2 polymorphs. However, the anatase phase was completely converted into rutile at temperatures above 700 °C. The particle size increased with increasing temperature. The same behavior was observed for the measured crystallite sizes. The Mn3+ ion charge was determined as the main valence for manganese ions in the TiO2 host. Oxygen vacancies are the probable crystal defects formed for charge balancing in the Mn-doped rutile structure. The results obtained for the powder with 3 % Mn and calcined at 800 °C demonstrated dopant cation segregation to form Mn2O3. It is important to emphasize that the absorbance values of the powders increase in the visible range when adding manganese compared to the absorbance values of pure TiO2. The band gap of the powders was reduced in accordance with the content of doping: from 3.04 eV (0 % Mn) to 2.05–2.20 eV (3 % Mn), with small differences depending on the calcination temperature. The increase in visible light absorbance led to a brown color in Mn-doped materials. Thus, the color intensity varied with the Mn content, ranging from light brown to dark brown powders. In conclusion, the temperature of 700 °C was established in this paper as the best condition to produce Mn-doped TiO2 pigments, based on the absence of anatase polymorph, small contents of residual carbon, and undetectable amounts of Mn2O3 due to segregation.

Hydrogen peroxide (H2O2) electrosynthesis via the oxygen reduction reaction (ORR) presents an attractive decentralized alternative to the industry-dominant anthraquinone process. Oxidized carbon materials have proven to be promising catalysts due to their low cost and facile synthesis procedures. However, the nature of the active sites is still controversial. The objective of this paper is to provide a critical review of the advances of this topic. The fundamentals of the ORR pathway and O-doping effects are described, followed by the experimental preparation methods for O-doped carbon, including chemical oxidation and electrochemical oxidation. To identify the contribution of each oxygen-containing functional group (OG) or combination of OGs towards 2-electron ORR, combined experimental and DFT calculation results were analyzed. This paper also reviews the new advancement in the co-doping of O and transition metals, which could realize high activity and high selectivity toward H2O2 generation. Future directions in this fascinating field are also highlighted.

In this paper, the structural, optical and magnetic properties of pure ZnO and Fe/Co co-doped ZnO nanoparticles are presented. Rietveld refinement of XRD pattern revealed the single phase wurtzite structure for prepared samples. FTIR study confirmed the formation of tetrahedral coordination between zinc and oxygen ions. SEM and TEM techniques were used to examine the morphology of samples. The absorption spectra showed the decrease in optical energy band gap with Fe/Co co-doping in ZnO. PL spectra demonstrated five peaks correspond to the ultraviolet region, violet, violet-blue, blue-green and green in the visible region. Emission peak in the UV region is attributed to near band-edge excitonic emission. Other four emission peaks in PL spectra are related to different defect states. M-H curve showed room temperature ferromagnetic (RTFM) behaviour of doped ZnO sample. This paper enhances the understanding of structural, optical and magnetic properties of Fe/Co co-doped ZnO nanocrystals for application in spintronics, solar cells, and ceramics.

In this paper, the dielectric properties and microstructure of lead-free ceramics with compositions of (1−x)Na 0.5 K 0.5 NbO 3 –xSrTiO 3 (NKN-ST) (x=0–0.15) are reported. The NKN-ST-based ceramics were synthesized using the conventional solid-state reaction method. When the amount of SrTiO 3 was increased, the crystal structure changed from orthorhombic to tetragonal and then pseudo-cubic symmetries, the Raman scattering spectra v 5 and v 1 modes shifted to lower wavenumbers, the grain size decreased, the dielectric relaxor behavior became stronger, and the Curie temperature shifted to a lower temperature. Furthermore, the transmission electron microscopy images and energy-dispersive spectroscopy spectra showed that the samples had a liquid phase at x≥0.08. Based on these results, it is suggested that SrTiO 3 doping in this system will cause the high temperature sintering and then cause the K-rich thin-layer liquid phase at the area around the grains which hinders the grain growth which is the response mechanism that changes the microstructure from an ordered to a disordered state. Besides, effect of microstructure on the dielectric relaxor behavior was proposed in this paper to explain the corresponding phenomenon. To the authors' knowledge, there is no reported data provided the direct evidences to show the SrTiO 3 doping effects on the microstructure of the system and therefore the change of long-order to short-order states.

This paper reports various critical processing parameters for the development of efficient ZnS doped with Cu, Al phosphors optimized to exhibit AC electroluminescence. Different firing atmospheres and temperatures were used for the synthesis of electroluminescent phosphor materials. As synthesized ZnS: Cu, Al phosphor powders were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Photoluminescence (PL) and Electroluminescence (EL) spectroscopy studies. Average crystallite size calculated from XRD lies in a range of 44–49 µm and average grain size as revealed by SEM lies in the range 3–5 µm. The results showed that the phosphor powders have hexagonal phase and exhibit near band edge luminescence in the blue region. This is one of very few reports that depict the observation of EL from hexagonal ZnS:Cu,Al phosphor system. Polycrystalline powders emit PL in a broad band with a maximum at 2.53–2.74 eV above the valence band. The PL spectrum of the ZnS:Cu,Al phosphor showed emission peaks at 453 nm, 467 nm, 485 nm and 490 nm that could be attributed to the generation of deep level energy traps. The prototype of an alternating current driven thick (40±2 µm) film EL device has been fabricated and the threshold voltage was observed to be around 95–120 V at a frequency of 1 kHz. The critical processing parameters for designing an efficient EL device have been highlighted and discussed thoroughly in the current paper.

In this review paper, the recent development on the adsorption of organic dyes by metal-doped porous carbon materials were reviewed. The primary objective of this paper is to sort out the dispersion information of metal-doped porous carbon materials widely used in organic dye adsorption. Various metal-doped porous carbon materials adsorbing organic dyes are summarized and discussed here for the first time. Key factors affecting the adsorption process such as the amount of doped metal, solution pH, and temperature are also reported and discussed. The adsorption mechanisms such as electrostatic interaction, π-π interaction, hydrogen bonding and synergistic interaction between metal particles and carbon materials are proposed for organic dyes adsorption on metal-doped porous carbon with the help of related works from the literature. Finally, few suggestions for future studies on metal-doped porous carbon materials are proposed.

In this paper, a novel heterojunction material was synthesized of C3N4 via doping with π-deficient conjugated pyridine ring molecules (2,6-diaminopyridine) and BiOCl by ultrasound-assisted method. First, doping C3N4 with 2,6-diaminopyridine can reduce the structural integrity and orderliness of C3N4, and reduce the number of structural fragments, Which makes C3N4 have more reactive sites. And then BiOCl nanosheets were grown on the surface of the modified C3N4 nanosheets to obtain a new heterojunction material composed of modified C3N4 doped with π-deficient pyridine ring molecules and BiOCl by the co-precipitation method. At last, the degradation of methyl orange (MO) by BiOCl, C3N4, modified C3N4 doped with 2,6-diaminopyridine, and a series of C3N4 doped with 2,6-diaminopyridine and BiOCl composite heterojunction materials under visible light was studied. X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), ultraviolet visible diffuse reflection (UV–Vis DRS) and transient photocurrent densities, and electrochemical impedance spectroscopy (EIS) were used to analyze the structure, morphology, and photogenerated charge transfer characteristics of samples. The experimental results show that the new heterojunction composite materials has better photocatalytic activity compared with pure BiOCl, C3N4, and modified C3N4 doped with 2,6-diaminopyridine. In addition, the degradation performance of methyl orange with different mass ratios of composite materials is also different. When the mass ratio of C3N4 doped with 2,6-diaminopyridine to BiOCl is 1:2, The composite material exhibits the best photocatalytic performance, which may be related to the synergistic effect of the modified C3N4 doped with 2,6-diaminopyridine and BiOCl. Based on the band structure and active species experiments, the reasons for the enhanced photocatalytic activity are discussed, and the possible degradation mechanisms are proposed. The research in this paper provides an effective new way to construct new heterojunction materials.

The main goal of the paper is to enhance the resistance to the bacteria of the hydroxyapatite deposited on Ti6Al4V alloy substrate. Hydroxyapatite coatings, enriched with SiC and Ag, were prepared and investigated for this paper. SiC was added to enhance film corrosion resistance, while by Ag addition the improvement of the antibacterial properties was foreseen. The coatings, with different Ag contents, were deposited on Ti6Al4V alloy substrates by co-sputtering of hydroxyapatite, SiC and Ag targets, using a magnetron sputtering system. The films were characterized in terms of elemental and phase composition, texture, morphology, corrosion resistance and antibacterial activity (Staphylococcus aureus MRSA, Staphylococcus aureus ATCC 29213, Streptococcus pyogenes ATCC 19615, Salmonella Typhimurium ATCC 14028), by EDS, XRD, FTIR, SEM and AFM techniques, electrochemical tests and antimicrobial tests. The influence of the Ag content on the film properties was also analysed. The antibacterial efficacies of hydroxyapatite versus Gram-positive bacteria are demonstrated if a small amount of Ag was added in their structure. The hydroxyapatite with Ag content less than 1 at% proves to have a good resistance to the bacteria attack, even if the content is reduced.

Nano sized semiconductor photocatalysts have a great scope for removal of large organic molecules like dyes and pesticides in an eco-friendly and sustainable manner. The photocatalytic decomposition of dyeing industrial wastewater produces negligible amount of solid by products. The problem associated with the existing catalysts are, their high band gap. Doping one catalyst with other suitable metals and metal oxides will enhance the efficiency of the photocatalyst and also makes the catalyst to be active in the visible region. The photocatalytic activity of the composite catalysts were highly improved through the modification in the crystallinity, micro structures, band gap, morphology, particle size and the surface area of the catalyst. This paper reviews the recent developments in the synthesis and application of composite photocatalysts. The role of synthetic pathways on the structure and activity of composite catalyst derived from TiO2, CdS, WO3, SnS and ZnO were analyzed. This paper will be more helpful for the scientists working in the field of nano sized photocatalysis.

This paper proposes a sustainable and facile approach for the synthesis of photocatalysts in which shell waste is used as support material. The synthesized photocatalysts exhibited a significant performance in the mineralization of organic substances under solar irradiation or artificial lighting. Calcined abalone shell with a TiO2 loading of 23.4% led to a significant improvement in optical absorption: the degradation efficiencies of methylene blue (MB) after 140 min under UV light, vis light, UV–vis light, and natural sunlight were 93%, 96%, 100%, and 100%, respectively. Notably, the byproducts obtained after the degradation by commercial P25 TiO2 disappeared with the utilization of shell waste as support material. The Na, Sr, S present in the calcined abalone shell were doped into the substitutional sites of TiO2 and were indispensable to achieve the desired band-gap narrowing and photocatalytic performance; moreover, the Ti and Zn oxides in the calcined abalone shell acted as semiconductors and improved the charge separation efficiency of TiO2. Above all, this paper describes a green synthesis based on the use of waste seashell. This material acts as an excellent photocatalyst support for environmental pollution treatments, leading to the ‘control of waste by waste’ and opening up new possibilities for shell waste reutilization and sustainable chemistry.

In order to increase the resistive switching performance of Gd2O3 based memory devices, it was desirable to find the impact of multi-factors including thickness, deposition temperature and doping method on RRAM devices. In the present paper, we reported that decreasing the thickness of Gd2O3 film can increase the endurance of RRAM devices and high temperature deposited Gd2O3 based devices showed better uniformity as well as endurance. The reason of improvement for high temperature deposited devices was due to larger O defects content in Gd2O3 film compared with room temperature deposited Gd2O3 film. Moreover, the combination of thin and high temperature deposited Gd2O3 film can further improve the properties of RRAM devices while doping method integrating thickness and deposition temperature performed no advantages in properties compared with undoped devices. The study in this paper clarified the multi-factors induced effect of Gd2O3 film on resistive switching process, which may be applied in RRAM devices area.

This paper investigates the oxygen ion conductivity (OIC) of cathodic materials in Solid Oxide Fuel Cells (SOFCs) by molecular dynamics simulation. Although the oxygen diffusion coefficient (ODC) is known to be one of the major factors associated with the ion conductivity of cathodic materials in the SOFC, other major process factors are remained to be further investigated so that the related oxygen ion conductivity can be fully characterized and enhanced. In order to search for significant factors that affect the OIC in cathode, the characteristics of doping effect and temperature change are simulated via Molecular Dynamics approach and the results are presented in details in this study. Based upon the modeling results, it is realized that the OIC at 773 K can be greatly improved by using the catalyst of Gd1-xBaxCoyFe1-y (GBCF). And also, the highest OIC at 973 K can be greatly enhanced by using the catalyst of La1-xSrxCoyFe1-y (LSCF). In addition, the modeling results also indicate that both the doping ratio and operating temperature are of significant factors for both ODC and OIC. Although ODC is a metrics that can be used to evaluate the mobility of oxygen ions inside the catalyst for cathode materials, it does not comprehend the characters of materials. In order to be able to fully characterize the conductivity of cathodic materials in SOFC, significant factors of OIC including the lattice structure of materials, the concentration of oxygen vacancy, and the operating temperature are fully explored in this paper for detailed system characterization. The modeling results clearly indicate that as the working temperature increasing from 773K to 973K, the largest OIC change is given by LSCF, and the smallest OIC change is provided by GBCF. Also, the ODC curve of the GBCF possesses highest ODC values in medium working temperature range due to large numbers of oxygen vacancy generated by the cathode.

The tunnel oxide passivated contact (TOPCon) is a promising technology improving the efficiency of Si solar cells by cutting recombination losses and simplifying the solar cell design (1D junction design). The objective of this paper is to investigate possible contact materials having a high/low work function for passivated contacts thereby enabling the realization of a double-sided contact Si solar cell featuring n-type TOPCon on the front and p-type TOPCon at the rear side. The main part of this paper deals with the eligibility of thin atomic layer deposited (ALD) AZO (aluminum doped zinc oxide) interlayers sandwiched between n-TOPCon and ITO (tin doped indium oxide) in order to avoid sputter damage. It will be demonstrated that the insertion of ALD AZO improved the efficiency by 0.8% abs. and lead to a maximum efficiency of 20.2%. Finally, WO x and MoO x which have a high work function are identified as promising contact layers for p-TOPCon.

The paper describes the mechanism of changes in wall ceramics physical-mechanical properties and structure when additives of various types and quantities are doped. The authors come to the conclusion that composite modifications of ceramic mixtures improve their molding properties, reduce the firing temperature for 150-2000°C and increase resistibility and frost resistance of end products. These composition additives consist of crushed glass fine powder mixed with oil sludge in 1/5 proportion. The paper proves that these composition additives 30-35% reduce energy consumption in wall ceramics production and provides wall ceramics of high quality for civil and industrial engineering.

This paper reports on the luminescence studies of Eu 3+ -doped strontium fluoroapatite. The goal of this paper is to establish and characterize the possible sites for Eu 3+ substitution in Sr 5 (PO 4 ) 3 F lattice. Eu 3+ -doped Sr 5 (PO 4 ) 3 F phosphor was prepared by the solid state reaction method. The X-ray powder diffraction result of as-synthesized powder phosphor reveals the single phase Sr 5 (PO 4 ) 3 F and it also indicates that the incorporation of Eu 3+ ions does not affect the crystal structure. Photoluminescence (PL) studies of Eu 3+ -doped Sr 5 (PO 4 ) 3 F phosphor are performed to study spectral properties of the sample. Site-selective excitation and emission spectra together with the decay curves are investigated by site-selective laser-excitation spectroscopy. The three crystallographic sites for Eu 3+ ions are identified in the 7 F 0 → 5 D 0 excitation spectra by using a pulsed, tunable, and narrowband dye laser. The luminescence due to the 5 D 0 → 7 F J ( J = 1, 2) transitions under excitation at each crystallographic site exhibits its own spectral features. Three crystallographic sites in Sr 5 (PO 4 ) 3 F give rise to different crystal-field splits of the 7 F 1 and 7 F 2 multiplets. Heterovalent substitution by rare-earth ions (Eu 3+ ) for Ca 2+ positions in the hexagonal crystal lattice requires charge compensation. The charge-compensation mechanism, site symmetry, and the crystal-field strength on Eu 3+ in Sr 5 (PO 4 ) 3 F are discussed for better understanding of preferential substitution of Eu 3+ in the Sr 5 (PO 4 ) 3 F lattice.

The article reports the successful preparation of single-phase vanadium doped BaBi 2 Nb 2 O 9 ceramics. In the first part of the paper we would like to present the results of the XRD measurements, which allows us to determine the lattice parameters. The parameters do not change, which implies that the vanadium ions ordering of the crystal structure causes the decreasing number of defects. The conclusion stays consistent with the results of dielectric and thermal stimulated depolarization currents measurements, described in the second part of the paper. The pure BBN ceramics, as well as the ones modified by vanadium, show the frequency dependence of the dielectric response typical for relaxor ferroelectrics i.e. the significant reduction of SYMBOL 101 \f "Symbol" \s 12e‘ max and shift of the corresponding temperature ( T m ) towards higher values with the frequency increase. However the vanadium substitution causes a reduction of the value of parameters describing the relaxor properties.