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In this study, a series of Eu3+-doped NaBaBi2(PO4)3 red phosphors were synthesized by high-temperature solid-phase reaction method, and the phase structure and photoluminescence properties of the samples were investigated in detail. All the diffraction peaks of the phosphors with various Eu3+ concentrations are well matched with the NaBaBi2(PO4)3 standard phase, indicating that Eu3+ ions have no effect on the host structure. Under the excitation of 391 nm wavelength, the emission spectra consisted of four characteristic emission peaks at 595, 617, 656 and 703 nm, respectively. The strongest emission peaking at 617 nm originates from the 5D0 → 7F2 electron transitions of Eu3+ ions. The optimum concentration of Eu3+ ions in NaBaBi2(PO4)3:Eu3+ is 9% concentration. The phosphor exhibits strong absorption capacity in the near-ultraviolet region. The Commission International de I’Eclairage chromaticity coordinates of the NaBaBi2(PO4)3:Eu3+ samples are located in the red region, indicating that the phosphors are suitable red component to applied in near-ultraviolet-based white light-emitting diodes.

In the machining of complicated surfaces, the cutters with large length/diameter ratios are used widely and the deformation of the machining system is one of the principal error sources. During the process planning stage, the cutting direction angle, the cutter lead and tilt angles are usually optimized to minimize the force induced error. It may lead to a low machining efficiency for bullnose end mills, as the material removal rates are different largely for different machining angles. In this paper, the influence mechanism of the machining angles on the force induced error is studied based on the models of the instantaneous cutting force when the cutter flute traveling through the cutting contact point and the stiffness of the machining system. In order to evaluate the machining angles, the force induced error/efficiency indicator (FEI) is defined as the division of the force induced error and the equal volume sphere of the removed material. FEI is dimensionless, with the lower FEI, the lower force induced error and the higher machining efficiency. For optimal selection of the machining angles, the critical FEI is calculated with the constraint of force induced error and the desired material removal rate, and the critical FEI separate the set of the machining angles into two subsets. After the feed rate scheduling process, the machining angles in the optimal subset would have higher machining accuracy and efficiency, while the machining angles in the other subset have lower machining accuracy and efficiency. Through the machining experiment of five axis machining and freeform surface machining, the effectiveness and superiority of the proposed FEI method is verified with a bullnose end mill, which can improve the machining efficiency with the constraint of force induced error.

Emissions of soot particles exert crucial impact on human health and the environment. Previous researches show that a partial replacement of fossil fuels with oxygenated fuels is supposed to reduce soot emission. However, the crucial information of soot size distributions is unclear, although small particles are more dangerous than large particles. In this paper, dimethyl ether (DME) is selected among the oxygenated fuels for the investigation of the doping effect on nascent soot formation. DME was doped in the burner-stabilized rich premixed ethylene/oxygen/argon flames at various mixing ratios. Flame temperature profiles were measured using R-type thermocouples with radiation correction. A scanning mobility particle sizer (SMPS) with a sampling system was used to determine particle size distributions (PSDs) of soot-containing combustion products with immediate dilution. Thermo-gravimetric analysis (TGA) complemented with elemental analysis (EA) was conducted to detect the chemical properties of formed soot particles. Additionally, species profiles of the experimental flame conditions were provided from simulations. The experimental PSDs showed that DME addition could slow down soot evolution process, while lead to a slight increase in incipient soot with size below 4 nm. When DME added, the production of benzene was suppressed due to the reduced concentrations of acetylene and propargyl, and thus soot nucleation. Meanwhile, soot oxidiation was enhanced because the OH radical and the oxidizability of soot particles are both increased. Considering the slight increase of sub-4 nm soot, the effect of oxygenated-PAHs (OPAH) was emphasized. The production of OPAH suppressed soot surface growth, which leading to the relatively lower consumption of sub-4 nm soot in DME added flames. As a result, DME cannot be simply regarded as a clean fuel due to the enhanced formation of sub-4 nm soot particles. When applying oxygenated fuels into practice, it is necessary to pay more attention to the size distributions of the emitted particles, and conduct appropriate post-processing techniques to reduce the emissions of small particles.

Up-conversion (UC) phosphors with multiple functions are highly desirable for many potentially technological applications which can stimulate the miniaturization and multipurpose of modern devices. In this work, Tm3+- and Yb3+-codoped SrBi4Ti4O15 (SBT:xTm3+/Yb3+) nanoparticles have been first synthesized by a convenient EDTA-citrate method. The structures and morphologies of SBT:xTm3+/Yb3+ were measured by powder X-ray diffraction, Fourier transform infrared reflectivity spectra and scanning electron microscope. Under 980 nm excitation, SBT:xTm3+/Yb3+ exhibited strong near-infrared (NIR) and weak visible emissions. The UC emissions were unveiled to be tightly related to the Tm3+ concentration and the optimum concentration was determined as x = 0.01. The possible UC mechanism was proposed. Importantly, based on thermo-responsive fluorescence intensity ratio approach, the optical thermometric properties were characterized in the temperature range between 313 and 573 K. The maximum sensitivity of SBT:0.01Er3+/Yb3+ UCNPs was obtained as 7.5 × 10−4 K-1. Besides, excellent repeatability and stability were also realized by the thermal-cycling measurement. Furthermore, prominent photo-thermal (PT) effect was also achieved with a temperature coefficient being 0.81 °C∙mm2/mW. Under periodic laser stimulation, the PT effect of the sample displayed regular response, indicating that the PT effect can be expediently controlled by 980 nm laser. These results indicate that SBT:xTm3+/Yb3+ UCNPs could be potential candidates for temperature sensors and PT agents.

Here, we report a high-pressure study on corannulene up to 27.6 GPa using the diamond cell technique assisted by Raman and infrared spectroscopic measurements. The intermolecular interactions betwe...

Multi-functional up-conversion (UC) phosphors are highly desirable for many potentially technological applications. Here, Er3+- and Yb3+-doped SrBi4Ti4O15 (SBT:xEr3+/yYb3+) UC nanoparticles (NPs) have been successfully synthesized for the first time by a convenient EDTA-citrate approach. The structures and morphologies were characterized by powder X-ray diffraction, Fourier transform infrared reflectivity spectra, scanning electron microscopy, and transmission electron microscopy. Under 980 nm excitation, SBT:xEr3+/yYb3+ UCNPs exhibited bright green and weak red emissions. The UC emission properties were disclosed to be tightly dependent on the Yb3+ and Er3+ concentration and the involved UC mechanism was discussed. More importantly, the noncontact optical thermometric ability were assessed based on the thermo-responsive fluorescence intensity ratio (FIR) technique and the maximum sensitivity (Smax) of SBT:0.15Er3+/0.15Yb3+ UCNPs is about 0.0036 K–1. Excellent repeatability and stability were proven by the thermal-cycling measurements. Furthermore, prominent photo-thermal (PT) effect was obtained with the temperature coefficients (η) being 0.24 and 0.49 °C∙mm2/mW for SBT:0.15Er3+/0Yb3+ and SBT:0.15Er3+/0.15Yb3+ UCNPs, respectively, which showed that the incorporation of Yb3+ was a promising strategy to improve the PT capability. In addition, regularly dynamic response of the PT agent under periodic laser stimulation was also observed. These results imply that SBT:xEr3+/yYb3+ UCNPs could be potentially utilized in thermometers and PT agents.

The specific cutting energy can characterize the machinability of the cutter for a material, and its change is a reflection of the size effect in the metal cutting process. It is critical to study the cutting process using an energy-based processing signature method with the purpose of improving the machining performance. In this paper, a specific cutting energy calculation method is presented based on a mechanistic model, and an exponential function is used to describe the trend in the specific cutting energy with the average undeformed chip thickness. A dimensionless index with value of greater than 1, referred to as the Specific Cutting Energy Index (SCEI), is proposed to address the energy efficiency of the milling process and reflect the machining performance for different machining parameters. Machining experiments with 300 M steel are conducted to validate the effectiveness of the proposed model. Analyses are performed to determine the relationships between SCEI and the material removal mode, chip morphology, tool wear rate, and surface roughness. Based on these results, a feed rate scheduling method is proposed to obtain optimal machining strategies using SCEI, which is an effective way to achieve high-performance machining.

The feature of “curing at low temperature, directly used in extreme conditions” made the adhesion technique more suitable for engineering application. The superalloy was successfully bonded at high temperatures by a multi-components modified, phenix-silicone-based adhesive, through forming various ceramics and intermetallics. The intermetallization process not only modified the thermal expansibility of adhesive, but also improved the compositional continuity and reaction extent around bonding interface. With the heating temperature increasing from 500 °C to 1000 °C, various high-temperature-resistant phases in turn generated in adhesive, and the chemical reactions on interfaces became more and more intense. Eventually, the room temperature shear strength of joints calcined at 700 °C reached the maximum value of 28.3 MPa, and the high temperature strength was still up to 18.4 MPa at 800 °C. Moreover, after 6 thermal cycles, the residual strength for joints calcined at 700 °C almost remained ∼13 MPa. The exclusive adhesive absolutely facilitated the repair and connection of engineering superalloy.

In aviation and navigation, complicated parts are milled with high-speed low-feed-per-tooth milling to decrease tool vibration for high quality. Because the nonlinearity of the cutting force coefficient (CFC) is more evident with the relatively smaller instantaneous uncut chip thickness, the stable critical cutting depth and its distribution against different tool postures are affected. Considering the nonlinearity, a nonlinear dynamic CFC model that reveals the effect of the dynamic instantaneous uncut chip thickness on the dynamic cutting force is derived based on the Taylor expansion. A five-axis bull-nose end milling dynamics model is established with the nonlinear dynamic CFC model. The stable critical cutting depth distribution with respect to tool posture is analyzed. The stability results predicted with the dynamic CFC model are compared with those from the static CFC model and the constant CFC model. The effects of tool posture and feed per tooth on stable critical cutting depth were also analyzed, and the proposed model was validated by cutting experiments. The maximal stable critical cutting depths that can be achieved under different tool postures by feed per tooth adjustment were calculated, and corresponding distribution diagrams are proposed for milling parameter optimization.

Up-conversion (UC) oxides comprise a huge family of materials with abundant optical functionalities and they merit extensive research. Some members of this family have been modified with proper rare earth (RE3+) ions and their importance has recently been established in non-contact temperature sensors, although the thermal sensitivity (S) value was still low. In this study, we investigated Nd3+ and Yb3+ sensitized Ba4La2Ti4Nb6O30 (BLTN:xNd3+/Yb3+) with a tungsten bronze structure for use as optical thermometers for the first time. Under excitation at 980 nm, obvious near-infrared emissions corresponding to 4F7/2/4S3/2 → 4I9/2, 4F5/2/2H9/2 → 4I9/2, and 4F3/2 → 4I9/2 transitions were observed, and the UC mechanism involved was elaborated. Furthermore, the UC thermometric properties were investigated according to the fluorescence intensity ratio technique and the maximum S values determined for BLTN:xNd3+/Yb3+ (x = 0.12 and 0.16) samples were both higher than 0.03 K–1. The potential of BLTN:xNd3+/Yb3+ for use in optical thermometers was estimated based on comparisons with other active materials.

Reversible upconversion (UC) luminescence modulation by external stimuli (i.e. electric field, magnetic field, and light irradiation) is extremely attractive for applications in a broad range of fields, such as photoswitches, high-density optical data storage devices, and optical sensing. In this work, one kind of novel phosphor, Er3+-doped Bi4Ti3O12 (Bi4−xErxTi3O12) ceramics, prepared by a conventional solid-state reaction approach, is reported which exhibits both bright UC luminescence and a remarkable photochromic (PC) effect. The UC luminescence, PC effect, and the coupling between UC and PC performances were investigated in detail. It is found that the UC luminescence could be readily modulated by alternating visible light irradiation and a thermal stimulus, and a large reversible luminescence regulation has been achieved based on the PC reaction. Meanwhile, the modulation of UC luminescence was shown to tightly depend on the irradiation time and thermal treatment processes. In addition, the coloration and decoloration processes also exhibited good fatigue resistance. The mechanisms related to the UC emissions, PC processes, and luminescence modulation are also discussed. These results indicated that Bi4−xErxTi3O12 samples could be potentially utilized as a kind of optical data storage material.

This study aims to explore the potential use of fibrous K0.3Ti4O7(OH)1.7 (KTO(OH)) as adsorbent in the enrichment and segregation of Zabuye Salt Lake containing Li+. X-ray diffraction scanning (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infra-red (FTIR) and scanning electron microscopy (SEM) were used to study the phase and morphological properties of KTO(OH). The results showed KTO(OH) was stable in space and had many adsorption sites, with 47.34-m2/g BET surface area. Adsorption capacity is 27.63 mg/g. In addition, pseudo-second-order kinetic model was fitted to verify its adsorption process. After repeating five times, the circulating adsorption capacity can still reach 91.67% of the initial adsorption capacity. The mass loss ratio of KTO(OH) was 0.85% and KTO(OH) shows excellent performance of environmental protection and pollution-free.

K2Ti4O9, a photocatalyst lacks the response to visible light. This short article takes advantage of the ion exchange properties of K2Ti4O9 and Fe3+ cations that are intercalated to enhance photocatalysis by responding to visible light. The degradation of MB (methylene blue) by K2Ti4O9 treated with different Fe3+ cations amounts was studied, the optimal treatment concentration was determined and the photocatalytic performance was evaluated. The structure, morphology, and energy band characteristics of the photocatalyst were confirmed by XRD, SEM, XPS, UV–vis, PL, and electrochemical workstation.

The various applications of luminescence materials were generally based on the effective modulation of luminescence spectra. However, the research on reversible spectral regulation of up-conversion (UC) luminescence materials was still in its infancy stage. In this work, a class of smart phosphor, Er3+ and Yb3+-codoped SrBi8Ti7O27 (SBYT: xEr3+) intergrowth bismuth layer-structured ferroelectric, possessing fast sensitivity to visible light irradiation, was reported based on visible light driven photochromic effect. Through the alternate stimuli of light irradiation and heating treatment, the reversible regulation of UC luminescence was achieved accompanying with the switching of coloration and decoloration processes. The luminescence modulation degree tightly relied on the irradiation time and thermal treatment modes. The reversibility and stability properties were also revealed. Moreover, it is found that polarization treatment was an effective approach which can be adopted to improve the UC luminescence contrast. The maximum luminescence modulation ability of SBYT: xEr3+ reached up to 81.3% which was 131% of that un-polarized sample. It is believed that SBYT: xEr3+ ceramics can act as a promising candidate for optical data storage and anti-counterfeiting applications.

Highly effective surface-enhanced Raman substrates with shape-diversified silver nanostructures on Al foil (AlF) were fabricated by galvanic replacement reaction in micellar template which is easy to control, simple and cost-effective. Due to the localized surface plasmon resonance (LSPR) of silver nanostructures, the substrates were used as surface enhanced Raman substrates. The shape-diversified silver nanostructures on AlF exhibited stronger surface enhanced Raman scattering (SERS) effects compared with flowerlike Ag nanostructures on ITO glass substrate fabricated by electrodeposition in micellar template. The maximum Raman enhancement factor of 109 fold was obtained, which is 236 times larger than the flowerlike silver nanostructures on ITO glass substrate. The scanning electron microscope (SEM) images show that the size and shape of the nanostructures and surface morphology make a valuable contribution to SERS. Raman enhancement experiments of three Raman probes were studied, which shows that different vibrational modes of Raman probe affect SERS effect. The fabricated shape-diversified silver nanostructures on AlF fabricated by galvanic replacement reaction in micellar template are cheap, controllable and simple. It could be potentially useful in SERS field such as imaging applications and highly sensitive molecule detecting.

A general approach to asymmetrically localize nanoparticles (NPs) in larger polymeric nanostructures is demonstrated by coassembly of tadpole-like silver NPs (AgNPs) and amphiphilic block copolymers (BCPs). The tadpole-like AgNPs are prepared by template synthesis using a tailor-made A(BC)20 star polymer, namely poly(ethylene glycol)[poly(acrylic acid)-block-polystyrene]20 [PEG(PAA-b-PS)20 ], as template resulting in AgNPs decorated with twenty short PS chains and one long PEG chain, named Ag@PEG(PS)20 . The asymmetric distribution of these AgNPs in various polymeric nanostructures, e.g., spherical micelles, cylindrical micelles, vesicles, and sponge phase, is achieved via coassembly of the as-prepared Ag@PEG(PS)20 and PEG-b-PS in solution driven by the anisotropic nature of the Ag@PEG(PS)20 . This report not only provides a new strategy for the fabrication of tadpole-like NPs but also offers opportunity for off-center distributing NPs in hybrid assemblies, which may find applications in, e.g., sensing, catalysis, and diagnostics.

In situ Raman vibration characterization and angle-dispersive X-ray diffraction (ADXD) measurements were performed on Y2O3/Eu3+ nanotubes to study its lattice change behavior under high pressure. The Raman vibration and lattice reflection both show changes in behavior near 8–10 GPa. The lattice of the cubic structure of Y2O3/Eu3+ nanotubes exhibits two different lattice states related to forms of the micro local atom arrangement. The lattice states resulted from the local disorder of the lattice due to pressure-induced deformation of the YO6 octahedra under the high pressure.

Complex aerospace parts with difficult-to-cut materials AerMet100 etc. should be processed by five-axis milling at low spindle speed, in which the process damping cannot be ignored in stability analysis. Based on the established nonlinear process damping and relevant equivalent process damping coefficient model, a 3D stability lobe diagram (SLD) considering the finite amplitude stability is proposed. A novel indentation coefficient identification method of the nonlinear process damping is proposed by using the finite amplitude stability region, which avoiding the experiment identification of accurate critical cutting depth in inverse stability solution method, and a turning experiment is designed to identify the indentation coefficient of AerMet100 materials. Due to the distribution of process damping force is varied with the cutter-workpiece engagement (CWE) which can be changed by tool orientation, thus the critical cutting depth with considering or not the process damping under different tool orientation are compared and analyzed. The results indicate that critical cutting depth magnitude distribution can be affected by the process damping, and the percentage increase in cutting depth has significant relationship with tool orientation and the frequency response function (FRF). Finally, the influence rule of tool orientation on stability boundary is concluded and the optimization criteria is given.

We observed morphological modification of rod-shaped C60 solvate crystals using a facile hydrothermal method. The initial C60 rods were changed from smooth rods to rough rods, porous rods or pieces under different hydrothermal conditions. During the hydrothermal treatment, the initial samples underwent a decomposition-recrystallization process, which can be tuned by the content of alcohol in the hydrothermal solution, thereby leading to modification of the morphological properties of the initial C60 rods. In addition, the rough and porous C60 rods prepared in our work exhibit excellent photoluminescence intensities that are approximately 7 and 3 times higher than those of pure C60 powders, respectively. Our results suggest that the hydrothermal method is a potential route for fabricating fullerene materials with controllable morphologies and novel functions.

The temperature required for growth of mullite whiskers in heat-resistant adhesive was decreased to 700 °C based on solid-liquid-solid (S-L-S) mechanism. The bonding strength was increased by 23.1% (700 °C) ∼ 60.7% (1200 °C), and the maximal 32.3 MPa was achieved after sintered at 1200 °C. Moreover, the whiskers-grown adhesive also displayed better anti-damage capacity, and multiple grading fractures occurred during the test procedure, which was mainly due to the pull-out mechanism.

A series of high-temperature resistant aluminum (Al) phosphate (P) adhesives with different Al:P ratios were prepared using Si as the sole additive. The influence of Al:P ratio on the temperature-dependent composition and structural evolution of the adhesives and their bonding performance were systematically analyzed. The conversion of aluminum metaphosphate to aluminum orthophosphate during the heating process from 700 °C to 900 °C decreased with increasing Al:P ratio, which reduced the generation of micro cracks inside the adhesive. Higher Al:P ratios (≥1:1) were favorable for the generation of alumina, which then reacted with silicon oxide to form mullite phase at high temperatures. No mullite phase was generated for Al:P ratios lower than 1. Accordingly, increasing Al:P ratio effectively improved the bonding performance and thermal shock resistance of the adhesive. The bonding strength of adhesive with an Al:P ratio of 1:0.85 after calcination at 1300 °C was 35.7% and 112%, respectively, higher than those of adhesives with Al:P ratios of 4:5 and 1:2. Besides, the retention rates of their bonding strength were 48.8%, 28.6% and 7.9%, respectively, after 15 thermal shocks based on air-cooling from 1300 °C to RT.

High-pressure in situ angle dispersive X-ray diffraction (ADXRD) measurements combined with first-principles calculations were performed on hollow ZnMn2O4 microspheres up to 43.5 GPa at room temperature, and two high-pressure phases emerged at 15.9 GPa. Phase III was assigned to the CaMn2O4 type structure (space group Pbcm). It is supposed that phase II probably has a MgAl2S4 inverted spinel type structure (space group Imma). Moreover, phase I, phase II and phase III were probably coexisted when pressure was released. The compressional behaviors of phase I (space group I41/amd) and phase III were all determined. Besides, based on electronic band structure calculations, it was uncovered that phase I probably experiences a pressure-induced electronic topological transition (ETT) to a semimetallic state upon pressure, and phase III is a semimetallic state. Our results show that pressure play a dramatic role in tuning ZnMn2O4’s crystalline structures, electrical behavior and spin-state.

This study describes the pressure-induced behavior of ZnS nanosheets by synchrotron angle-dispersive X-ray diffraction (ADXD) measurement up to 32.7 GPa. ZnS nanosheets transform from zinc blende structure to rock salt phase at 13.1 GPa and subsequently to a Cmcm structure at 20.3 GPa. The transition to the Cmcm structure is irreversible for ZnS nanomaterials at a much lower critical pressure than required for ZnS bulk materials. The special morphology of ZnS nanosheets plays a crucial role in the transition to Cmcm structures at comparatively low pressure. Continuous changes in lattice volume in the absence of volume collapse are observed after the transition from rock salt to the Cmcm structure occurs.

A “cobalt-free” double perovskite electrode material with stoichiometric composition Sr 2 FeTiO 6− δ (SFT) has been developed for intermediate-temperature solid oxide fuel cells (IT-SOFCs) using Ce 0.8 Sm 0.2 O 1.9 (SDC) electrolyte. The reactivity tests show that the SFT electrode is chemically compatible with the SDC electrolyte at 1100 °C for 10 h. The electrical conductivity of SFT sample reaches 2.83–2.33 S cm −1 the temperature range of 600–800 °C. The thermal expansion coefficient of the SFT sample is 16.8×10 −6 K −1 the temperature range of 30–1000 °C in air, which is lower than that of most of the reported Co-based electrodes. Using NiO–SDC as anode, SFT as cathode, and SDC as supported electrolyte, the single cell exhibits maximum power density of 441 mW cm −2 at 800 °C. The area specific resistances of the SFT electrode on SDC electrolyte calcined at 1000 °C were found to be 0.051, 0.094 and 0.204 Ω cm 2 at 800, 750 and 700 °C, respectively. Maximum power density of 335 mW cm −2 has been achieved for a symmetrical single cell with the configuration of SFT/SDC/SFT at 800 °C with wet H 2 as fuel and ambient air as oxidant. These results indicate that SFT is a very promising electrode candidate for IT-SOFCs with SDC electrolyte.

The cubic perovskite phase, Ba 0.9 Sr 0.1 Co 0.9 In 0.1 O 3− δ (BSCI), has been investigated as an alternative cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The BSCI exhibited a good chemical compatibility with the Ce 0.8 Sm 0.2 O 1.9 (SDC) electrolyte at 1000 °C for 5 h. The In-doping resulted in a dramatic reduced thermal expansion coefficient. Its electrical conductivity is 8.7–13.6 S cm −1 over the temperature range of 600–800 °C. The area specific polarization resistance of BSCI cathode in air are 0.079 Ω cm 2 , 0.151 Ω cm 2 , and 0.376 Ω cm 2 at 700 °C, 650 °C and 600 °C, respectively. Maximum power density as high as 565 mW cm −2 at 800 °C. Preliminary results imply that BSCI is a promising cathode candidate for IT-SOFCs.

In this work, uniform Zn2SnO4 nanoparticles were synthesized with a simple co-precipitation method followed by hydrothermal post-treatment process. For comparison, pure ZnO and SnO2 samples were obtained with the same method. These products were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and N2 absorption–desorption analysis. The ethanol-sensing properties of as-prepared Zn2SnO4 nanostructure sensor was systematically investigated and compared with the pure ZnO and SnO2 sensors. The results revealed that the Zn2SnO4-based sensor exhibited a low operating temperature, high response, good repeatability, and long-term stability toward ethanol gas.

The BaBi 0.05 Co 0.8 Nb 0.15 O 3− δ (BBCN) oxide has been synthesized by the traditional solid-state reaction method and characterized for its application as new cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The single phase BBCN having a cubic perovskite structure is obtained by Bi and Nb doping on the Co site in BaCoO 3− δ . The electrical conductivities of the BBCN sample are 8.8–12.5 S cm −1 in the temperature range 600–800 °C in air. The average thermal expansion coefficient (TEC) is 20.7 × 10 −6 K −1 in the range of 30–1000 °C in air. The activity of BBCN for oxygen reduction reaction (ORR) is tested by symmetrical cell and single fuel cell tests. The area specific resistance (ASR) of a BBCN cathode with LSGM electrolyte is 0.073 Ω cm 2 at 700 °C in air. A maximal power density of 610 mW cm −2 is achieved at 800 °C. The BBCN cathode has shown a good electrochemical stability for 24 h short-term cell test. The experimental results indicate that BBCN can be a promising cathode candidate for IT-SOFCs.

We fabricated mono-dispersed hollow waxberry shaped β-quartz GeO2 by a facile one-step synthesis in emulsion at room temperature. TEM images indicated that hollow waxberry shaped GeO2 were consisted of nano-sphere whose average size were estimated to be 20 nm. The growth mechanism and optical properties of the products were also investigated. It was found that addition of n-butanol and PVP were crucial factors to control the morphology of GeO2. The possible formation mechanism of the hollow interior is proposed as the Ostwald ripening. The optical properties of the β-GeO2 nanoparticles with hollow shapes were also studied with photoluminescence spectrum, which reveals a broad emission, suggesting potential applications in electronic and optoelectronic nanodevices. These attractive results provide us a new simple method further used to fabricate other specific hollow structure and indicate hollow waxberry shaped GeO2 may have potential applications in light-emitting nanodevices.

In situ upconversion photoluminescence measurements of Y2O3/Eu3+ nanotubes under high pressure were carried out with 632.8 nm laser light excitation. The intensity of 5D0–7FJ (J = 0,1,2) transitions increased up to 8.2 GPa due to the enhanced crystal filed with pressure, while above 8.2 GPa, the photoluminescence intensity decreased rapidly. Full width of half maximum (FWHM) of 5D0–7F0,1,2 transitions and I0–2/I0–1 of the Eu3+ ion luminescence both exhibited obvious changes near 8.2 GPa, indicating the presence of short-range structural changes in the vicinity of the Eu3+-ion. The observed changes reflected a disordering of local micro-structure in the vicinity of Eu3+-ions resulting from the short-range distortion of YO6 octahedra under pressure. The luminescence of doped Eu3+ ions acted as an effective probe to reveal slight changes in structure and the local crystalline environment of Y2O3/Eu3+ nanotubes under high pressure.

In this paper the electron transport characteristic of GaN photocathode is simulated. After the electrons got across the band bind region and reached to the cathode surface, the distributing of electron energy is 2.3∼3.4 eV. And the surface electron escapes probability of GaN photocathode with different energy is changing with the structure of surface barrier. The barrier I is more impotent that affecting the surface electron escapes probability than that of barrier II, its structure is determined the electron transport characteristic. And in the vacuum, the electron energy that corresponding to the peak electrons number is 2.95 eV.

Soda-lime sintering process and lime sintering process are the research focus on utilization of low-grade alumina recently. The latter process can realize dry-sintering process and its energy consumption is relatively lower. However, its sintering temperature is up to 1350 °C, which is unfavorable to industrial production. Based on lime sintering method, a novel process of alumina production from low-grade bauxite containing sulfur or fly ash is carried out in this paper. The phase of alumina transforms from 12CaO·7Al2O3 (C12A7) to 4CaO·3Al2O3·SO3 (C4A3S), whose alumina leaching property is better, through decreasing sinter temperature and time and adjusting the content of CaSO4 of the raw materials of lime sintering process. The main phases of the clinker sintered at 1250 °C are C4A3S and silicon dioxide. Its leaching ratio reaches 89% after 10 min reaction, and the conditions of leaching temperature and sodium carbonate’s concentration are lower than that of C12A7.

We have synthesized a series of high quality EuTi1−xCrxO3 (x = 0.0, 0.02, and 0.04) nanoparticles by simple sol–gel technique. The averaged grain size of these obtained nanoparticles displays no obvious change with Cr-doping and is about 100 nm. The structural and magnetic properties of EuTi1−xCrxO3 (x = 0.0, 0.02, and 0.04) samples were detailedly investigated. It is found that the G-antiferromagnetic (G-AFM) ordering of pure EuTiO3 can be significantly modified with slight Cr-doping, and finally the ferromagnetic behavior is enhanced for EuTi1−xCrxO3 system with Cr-doping.

In this paper, we report the in situ high pressure X-ray diffraction studies on Er{sup 3+} doped Gd{sub 2}O{sub 3} in a diamond anvil cell up to 39.8 GPa at room temperature. Several phase transitions have been identified in our studies. The structural transformation from a starting cubic phase to a hexagonal phase occurred during the sample compression process, at 8.57 GPa. And the hexagonal phase was stable from 12.5 GPa up to the highest pressure in this study but was not quenchable and transformed to a monoclinic phase after pressure release. An anomalous high pressure behavior in the hexagonal type Gd{sub 2}O{sub 3} phase was observed, which might be caused by an electron transition influenced by Er{sup 3+} ions doping. By fitting the compression data to the Birch-Murnaghan equation of state, the bulk moduli of the cubic and two hexagonal (at p 27.0 GPa) Gd{sub 2}O{sub 3} phases were determined to be 164 {+-} 3, 185 {+-} 7, and 150 {+-} 10 GPa with B'{sub 0} = 4, respectively.

The structural phase transition of CdSe/ZnS core/shell quantum dots (QDs) has been studied by in situ angle-dispersive X-ray diffraction under high pressure up to 53.6 GPa. The CdSe core transforms from wurtzite to rock-salt structure near 6.3 GPa and then to Cmcm or distorted Cmcm structure probably occurs at 45.1 GPa which has not been observed in CdSe nanomaterials before. The critical pressure from wurtzite to rock-salt and the bulk modulus of rock-salt phase are much higher than those for bulky and uncapped nanoparticle CdSe. The released sample can be kept in rock-salt phase for a certain time, verified by photoluminescence (PL) spectra, quite different from the reversible transition for pure CdSe. A reasonable interpretation of the experimental phenomena is given by comparing the bulk modulus of the core and shell and studying the stress sate of the core after decompression. Our study suggests that capping a hard shell is an effective approach to quench the high pressure phase of nanomaterial with a reversible phase transition.

CeO 2 undergoes a first-order phase transition from fluorite to α-PbCl 2 -type structure under high pressure. To evaluate the changes in physical properties of CeO 2 nanomaterials as the particle size decreasing, high-pressure Raman study under quasi-hydrostatic condition has been performed on CeO 2 nanospheres self-assembled by 5 nm CeO 2 nanoparticles at room temperature. Surprisingly, as the pressure elevate to 34 GPa, the CeO 2 nanospheres still retain the cubic fluorite-type structure, indicating the sample is more stable than the bulk counterpart. Whereas, previous high-pressure studies show the phase transition at 22.3/26.5 GPa for 12 nm CeO 2 nanoparticles, which is less stable than the bulk materials. The enhancement of phase stability might be attributed to the increase of surface energy of CeO 2 nanospheres as the size of the building units decrease.

In-situ high-pressure X-ray diffraction and Raman spectroscopies have been performed on well-shaped CeO2 nano-octahedrons enclosed by eight (111) planes. The CeO2 nano-octahedrons are shown to be more stable than their bulk counterparts and some other reported CeO2 nanocrystals of smaller size. The transition pressure from cubic to orthorhombic phase is approximately 10 GPa higher than that of 12 nm CeO2 nanocrystals even though they have similar volume expansion at ambient conditions. Additionally, the phase transition to α-PbCl2 phase is very sluggish and uncompleted even up to 55 GPa. The TEM image of the sample after decompression from 55 GPa clearly shows that the nano-octahedrons preserve the starting shape. Such distinct high-pressure behaviors in CeO2 nano-octahedrons have been discussed in terms of their special exposure surface. Further analysis shows that the lower compressibility of the exposed (111) planes in the nano-octahedrons is believed to be the major factor to the elevation of the phas...

Polyvinylpyrrolidone (PVP)-capped rutile GeO2nanoparticles were synthesized through a facile hydrothermal process. The obtained nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), and photoluminescence spectroscopy (PL). The capped GeO2nanoparticles showed significantly enhanced luminescence properties compared with those of the uncapped ones. We attributed this result to the effect of reducing surface defects and enhancing the possibility of electron-hole recombination of the GeO2nanoparticles by the PVP molecules. PVP-capped GeO2nanoparticles have potential application in optical and electronic fields.

The study of pressure behavior for ZnS nanorods by X-ray diffraction measurements up to 37.2 GPa is carried out. ZnS nanorods transform from the initial wurtzite phase to rock salt phase at 19.6 GP...

Monodisperse CeO 2 nanospheres with the average size of 40 nm, self-assembled by well-crystalline CeO 2 ultrafine nanoparticles were synthesized through a facile solvothermal route using n-butanol as solvent in the absence of any surfactant or template. The formation process of the monodisperse self-assembly CeO 2 nanospheres is briefly discussed. The key function of n-butanol is investigated by comparative experiments. It is found that n-butanol not only serves as solvent, but also acts as surfactant in the formation of monodisperse self-assembly CeO 2 nanospheres. Raman and XRD spectra show that the sample is pure cubic fluorite type of structure. Compared to the bulky CeO 2 materials, the prepared CeO 2 nanospheres exhibited an obvious blue-shifting in UV absorbance. The direct band gap energy of the obtained sample increases by exceeding 10%. Our study provides an effective approach to control CeO 2 morphology which has potential application in synthesis of other nanomaterials.

We studied the coating of C60 nanorods with nickel by electroless plating method and investigated their magnetic properties. The morphology and structure of the nickel layer coated on C60 nanorods were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Raman spectroscopy. The coated nickel is in the form of nano-sized crystals and becomes a continuous layer as reaction time increases. The hysteresis loop shows a super paramagnetic characteristic similar to that of nanometer-sized nickel particle. These results suggest that the average size of nickel particles on C60 rods is below 10 nm. Our study has shown that electroless plating is an efficient and simple method for coating C60 nanorods with nickel.

Efficient upconversion photoluminescence (UCPL) has been observed from CdSe/ZnS quantum dots excited at both visible and NIR wavelength, 633 and 830 nm, respectively. The UCPL excited at 633 nm exhibits a linear power dependence, while the UCPL excited at 830 nm shows a quadratic power dependence with an energy gain as high as 660 meV. The UCPL was studied under hydrostatic pressure up to ∼8 GPa at room temperature compared with the pressure dependence of normal PL excited at 514 nm. Our investigation reveals that the UCPL excited at 633 and 830 nm originate from two different energy states with two different up-conversion processes. The UCPL excited at 633 nm originates from phonon populated surface states, which are not trapped to the band edge. The UCPL excited at 830 nm originates from the band edge, and two-photon absorption is the likely up-conversion excitation mechanism.

We report a facile method to prepare gold nanoparticles by atmospheric plasma. Chitosan, was used as a stabilizing agent and gold precursor. In chitosan solution was reduced by atmospheric plasma at room temperature. We find the plasma treatment is effective for reducing the gold precursor and the process only takes minutes. The obtained gold nanoparticles were characterized with UV-vis spectroscopy and transmission electron microscopy. The results indicated that the morphology and size distribution of gold nanoparticles prepared varied with treatment time and the ratio of chitosan to precursor metal salts. Additionally, a preliminary study on air component analysis indicated that the moisture in air plays an important role in producing the active ingredient for the production of gold nanoparticles.

Contrast with conventional dielectric tunable materials such as barium strontium titanate (BST), here, we report one new dielectric tunable behavior for Sr 1-x Pr x TiO 3 system at low temperature. Giant dielectric tunability is confirmed in this system. More importantly, the efficient dielectric tunability can be realized just using small bias field. In addition, critical threshold electric field is also confirmed. This phenomenon may be related with the competition interaction of polar state with quantum fluctuations.

ZnS nanorods in a wurtzite structure with an average diameter of 10 nm were synthesized via a solvothermal method. In situ photoluminescence and Raman spectra measurements on the ZnS nanorods under high pressure were carried out using a diamond anvil cell. The disappearance of the photoluminescence (PL) band and longitudinal-optical (LO) phonon mode indicates that the ZnS nanorods transform to the rock salt phase near 16.7 GPa. A visible change in the pressure dependence of the full width at half magnitude for the PL band and LO phonon was found near 9 GPa, indicating that a phase transition of the ZnS nanorods from the wurtzite phase to the zinc blende phase probably occurs. High pressure can obviously modulate the PL band of the ZnS nanorods-it shifts to a long wavelength band with increasing high pressure.

The controllable synthesis of ZnS nanocrystals with desirable morphology and correlative structure has been carried out via the solvothermal method by simply changing the molar ratio of the reactants. The hexagonal-shaped ZnS nanosheets with a zinc-blende structure were synthesized in one step for the first time. ZnS nanorods with wurtzite structure and large ratio of length to diameter were also fabricated. We found that phase transformation is easily induced and there is a strong correlation between the morphology and structure of the ZnS nanocrystals by changing the ratio of the reactants. The photoluminescence spectra of the ZnS nanosheets and nanorods exhibit different emission bands. ZnS nanosheets show a strong emission at 534 nm while the nanorods have two emissions located at 520 and 578 nm.