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We report the design, synthesis, structure, and properties of two complex layered phosphide nitrides, $Ak$Th$_2$Mn$_4$P$_4$N$_2$ ($Ak$ = Rb, Cs), which contain anti-fluorite-type [Mn$_2$P$_2$] bilayers separated by fluorite-type [Th2N2] layers as a result of the intergrowth between AkMn$_2$P$_2$ and ThMnPN. The new compounds are featured with an intrinsic hole doping associated with the interlayer charge transfer and a built-in chemical pressure from the [Th$_2$N$_2$] layers, both of which are reflected by the changes in the lattice and the atomic position of phosphorus. The measurements of magnetic susceptibility, electrical resistivity, and specific heat indicate existence of local moments as well as itinerant electrons in relation with d-p hybridizations. The expected dominant antiferromagnetic interactions with enhanced d-p hybridizations were demonstrated by the first-principles calculations only when additional Coulomb repulsions are included. The density of states at the Fermi level derived from the specific-heat analysis are 3.5 and 7.5 times of the calculated ones for Ak = Rb and Cs, respectively, suggesting strong electron correlations in the title compounds.

The antiferromagnetic topological insulator has attracted lots of attention recently, as its intrinsic magnetism and topological property make it a potential material to realize the quantum anomalous Hall effect at relative high temperature. Until now, only MnBi2Te4 is predicted and grown successfully. The other MB2T4-family materials predicted (MB2T4: M = transition metal or rare earth element, B = Bi or Sb, T = Te, Se, or S) with not only antiferromagnetic topological property but also rich and exotic topological quantum states and dynamically stable (or metastable) structure have not been realized on experiment completely. Here, MnBi2Te4 single crystals have been grown successfully by us. It shows typical antiferromagnetic character with Neel temperature of 24.5 K and a spin-flop transition at H ≈ 35,000 Oe, 1.8 K. In order to obtain the other members of MB2T4-family materials, it is necessary to understand the growth mode of MnBi2Te4. Its growth mode may be the layer-inserting growth mode based on symmetry, which is supported by our X-ray photoelectron spectroscopy (XPS) result, as the intrinsic chemical states of Mn and Te of MnBi2Te4 are the same with those of inserting material α-MnTe. Understanding the growth mode of MnBi2Te4 can help us to grow the other members of MB2T4-family materials.

The development of photosensitive slurries for additive manufacturing has attracted great interest due to their correlation with the final properties of the fabricated parts. This paper focus on the printing quality control in digital light processing (DLP) 3D printing of advanced ceramics. Systematic experiments were performed to assess the effects of the exposure time and printing angle on the three-point bending strength of the fabricated samples. The exposure time affected the bending strength of the printed zirconia ceramic dramatically. When the weak exposure time is 1 s and the strong exposure time is 13 s, the average bending strength can reach 580 MPa while Weibull modulus can reach 8.84. Meanwhile, the printing angle also affected the bending strength mechanical sample printed at 45° exhibits the worst performance.

Solid Oxide Fuel Cells (SOFCs) are environmentally efficient energy conversion devices, but are partially limited by the complicated fabrication procedure. In this work, dense 8 mol% yttria-stabilized zirconia (8YSZ) ceramics were successfully realized through a DLP (digital light processing) stereolithography method and the electrolyte self-supported fuel cell was also tested at 800 °C. The sintering behavior of the as-printed planar samples were investigated and a fully dense ceramic can be achieved at 1450 °C. The total conductivity of the sintered 8YSZ can reach 2.18 × 10−2 S cm−1 at a test temperature of 800 °C, which is acceptable for practical application. For the electrolyte self-supported fuel cell test, a power density of 114.3 mW cm−2 can be achieved when Ni-8YSZ cermet and La0.8Sr0.2MnO3 (LSM) were used as anode and cathode. It was demonstrated that 3D printing is a promising processing technique to build up electrolyte self-supported SOFCs with desired structure for the future development.

Based on anti-perovskite Mn3ZnN, the negative thermal expansion (NTE) temperature can be effectively broadened via co-substituting Sn, Mn. Using optimized components, the room-temperature NTE effect covering a wide temperature range can be realized. Both the competing ferromagnetic order from Mn and local lattice disorder from Sn should be the reason for the physical origination of the broadening of the NTE temperature. By compositing with epoxy, the low thermal expansion could be achieved around room temperature, which exhibits great potential in the field of electronic packaging.

We have synthesized a new series of layered oxyselenides La2O3(Mn1−xCox)2Se2 through a solid state reaction method. Their structure and physical properties were studied through powder X-ray diffraction, electric transport measurements, absorption spectroscopy, bulk magnetization and specific heat experiments. These compounds crystallize in layered structures with the space group I4/mmm. All the samples present semiconducting or insulating behavior with the activation energy ranging from 0.134 eV to 0.400 eV. The ferromagnetic (FM) component is induced as Co enters the lattice, and the FM component raises to its maximum when x is 0.6. The competing of FM and antiferromagnetic (AFM) components led to the emergence of a spin-glass like behavior in the intermediate alloys.

The Pb39Bi25Sn36 alloy was directionally solidified at varied withdrawal rates followed by quenching. From metallographic observation, composition analysis and differential scanning calorimetry (DSC) analysis, the solidification sequence of Pb39Bi25Sn36 alloy was characterized. The Sn-dendrite is observed as the primary phase during solidification, followed by the β(Pb7 Bi3 )/Sn divorced eutectic. At lower temperatures, the β(Pb7Bi3 )/Sn binary eutectic is formed in the interdendritic region. However, the quasi-peritectic reaction [L+α-Pb→β(Pb7 Bi3 )+Sn] does not occur as the prediction based on ternary phase diagram analysis, which can be attributed to the unequilibrium solidfication condition. Moreover, the as-cast microstructure is significantly refined with the increasing withdrawal rates. The quenched sample only exhibits the lamellar structure of Sn, β(Pb7Bi3) and Bi phases. The results can provide instructions to optimize the as-cast microstructure of ternary alloys with quasi-peritectic reaction.

We report the superconductivity of a new quaternary compound ThMo$_2$Si$_2$C, synthesized with the arc-melting technique. The compound crystallizes in a tetragonal CeCr$_2$Si$_2$C-type structure with cell parameters of $a$ = 4.2296 \r{A}and $c$ = 5.3571 \r{A}. An interlayer Si-Si covalent bonding is suggested by the atomic distance. The electrical resistivity and magnetic susceptibility measurements indicate a Pauli-paramagnetic metal with dominant electron-electron scattering in the normal-state. Bulk superconductivity at 2.2 K is demonstrated with a dimensionless specific-heat jump of ${\Delta}C/\gamma_{\rm n}T$ = 0.98. The superconducting parameters of the critical magnetic fields, coherence length, penetration depth, and superconducting energy gap are given., Comment: 14 pages, 6 figures, 3 tables. Accepted for publication in SCIENCE CHINA Physics, Mechanics & Astronomy

The effect of powder characteristics on the thermal conductivity and mechanical properties of silicon nitride (Si 3 N 4 ) ceramics were investigated systematically by using two α-Si 3 N 4 powders a ...

Bi12TiO20-based composite ceramics were prepared by sintering a mixture of presynthesized Bi12TiO20 and a second phase around the melting point of Bi12TiO20. These ceramics can exhibit direct as well as inverse piezoelectricity without electrical polarization, and become competitive piezoelectric material with high depoling temperature and stable thermal behavior. However, their piezoelectric constants were, in general, relatively low and do not remain consistent for both the symbol and magnitude over the entire surface. To prevent the permeation of melting Bi12TiO20 into substrate and thus create the inhomogenous amorphous content, samples were sintered on Al2O3 (0001) single crystal substrate. Compared to samples sintered on Al2O3 ceramics, piezoelectric coefficient (d33) of these samples was increased by 80%. Moreover, the symbol of d33 is identical on the whole surface. Here, the enhanced piezoelectricity might be ascribed to increased alignment of distorted BiO5 polyhedra in amorphous Bi12TiO20 phase. These results provided a method to improve the piezoelectric properties of Bi12TiO20-based ceramics and provided some inspiration for further development of Bi12TiO20-based ceramics suitable for practical applications.

We have synthesized a new series of layered oxyselenides Bi 2 LnO 4 Cu 2 Se 2 (Ln=Nd, Sm, Eu, Dy, Er, Yb). Their crystal structures and physical properties were studied through X-ray diffraction, electric transport measurements, bulk magnetization and first-principle calculation. All these compounds have a tetragonal structure with space group I4/mmm. They exhibit hole-type metallic behaviours which is also verified by the DFT calculation. The new Bi 2 LnO 4 -type block in these compounds may give people some enlightenment in synthesizing new iron-based superconductors or other layered compounds.

(CoCrFeNi)94Ti2Al4 high entropy alloy (HEA) was fabricated through drop-casting and conventional thermo-mechanical processing. After cold rolling and recrystallization heat treatments, the tensile properties were investigated at room temperature (RT), 573 K, and 873 K, respectively. At RT, the stress-strain curve exhibits non-serration. However, with the increasing tensile temperature from 573 K to 873 K, the serration evolves from type A + B to type C, and the maximum stress drop rises from 15.0 MPa to 24.7 MPa. At 873 K, C-type serration first appears at the yield strain, but finally disappears when the plastic strain above 12%. Transmission electron microscopy (TEM) analysis indicates that the simultaneous effects of twinning boundary and high density dislocations promote the dynamic precipitation of nanoscale L21-Heusler phase during tensile deformation.

A member of antiperovskite manganese compound Mn3PdN was successfully synthesized. The structural, magnetic, electrical, and thermal transport properties were investigated systematically. The results indicated that Mn3PdN is a weak correlated system. A first-order paramagnetic (PM) to antiferromagnetic (AFM) transition occurred at 285 ​K (TN) combining with an abrupt change in structure. Mn3PdN exhibits multifunctional properties such as near-zero temperature coefficient of resistivity (TCR) and negative thermal expansion (NTE).

Herein, Dy3+ doped indium nitride nanosheets with ferromagnetism at room-temperature were synthesized via a vapor - solid phase nitriding reaction. The as-synthesized samples exhibit clear ferromagnetism at room-temperature. The ferromagnetic properties of the samples could be changed by doped Dy3+. The saturation magnetization value of various Dy3+ doped indium nitride nanosheet samples display a parabolic-like change with the Dy3+ doped content increase and reaches the top value of 0.1455 emu g−1 corresponding to the Dy3+ doped content of 1.06 at. % at room temperature. The magnetic properties were originated from the d-f interaction between localized carriers and adjacent rare earth Dy3+ ions in the carrier orbits based on the first-principles calculation. The as-synthesized Dy doped indium nitride nanosheets can be widely used in spintronic devices due to the room temperature ferromagnetism.

The effect of heat treatment on the in-line transmittance of BaZr 0.5 Ce 0.3 Y 0.2 O 3−δ (BZCY532) ceramics prepared by spark plasma sintering method was investigated. The loss of Ba in transparent BZCY532 ceramics is the key reason for the loss of transmittance during the annealing process. This problem can be effectively alleviated by using a powder bed of BZCY532. Heat treatment atmospheres, wet air and dry air, were also found to be critical for obtaining high quality transparent ceramics. A highly transparent BZCY532 ceramic with the in-line transmittance (T in ) of 71.4% at 2000 nm can be obtained by using SPS method followed by an annealing in powder bed at 1500 °C in wet air.

For a magnetic confinement fusion device, the superconducting magnets and busbars need to be insulated with one layer of solid insulation to isolate the high voltage potential from the ground. The insulation layer commonly consists of several interleaved layers of epoxy resin-impregnated glass fiber tapes and polyimide films. The traditional electrical inspection methods for such solidified insulation on the magnet and busbar are a DC voltage test or a Paschen test. These tests measure the quality of the insulation based on the value of leakage currents. However, even if there is a larger quantity of high dielectric strength material implemented, if there are some microcavities or delaminations in the insulation system, the leakage current may be limited to microampere levels under testing levels over dozens of kilovolts. Therefore, it is difficult to judge the insulation quality just by the magnitudes of leakage current. Under long-term operation, such imperceptible defects will worsen and finally completely break down the insulation because of partial discharge (PD) incidents. Therefore, a PD detection test is an important complement to the DC voltage and Paschen tests for magnet and busbar insulations in the field of fusion. It is known that the PD detection test is a mature technique in the electric power industry. In this paper, the PD characteristics of samples containing glass fiber-reinforced composite insulations for use with the superconducting busbar were presented and discussed. Various samples with different void contents were prepared and the PD behaviors were tested.

Recently, An electron-doped 12442-type iron-based superconductor BaTh$_2$Fe$_4$As$_4$(N$_{0.7}$O$_{0.3}$)$_2$ has been successfully synthesized with high-temperature solid-state reactions on basis of a structural design. The inter-block-layer charge transfer between the constituent units of "BaFe$_2$As$_2$" and "ThFeAsN$_{0.7}$O$_{0.3}$" was found to be essential to stabilize the target compound. Dominant electron-type conduction and bulk superconducting transition at ~22 K were demonstrated., Comment: 16 pages in total. 5 figures, 1 table (main article); 6 figures, 3 tables (Supporting Information)

The ceramic honeycomb sandwich structures of 3 mol% yttria-stabilized tetragonal ZrO2 (3Y-TZP) material were fabricated by an additive manufacturing technique based on the digital light processing (DLP) system. The bending behaviour of hexagonal and square honeycomb sandwich structures was investigated with three-point bending test. The effects of geometric parameters, including the thickness of the face-sheet, the height of the cell, the thickness of the cell wall and the size of the cell, were studied through experiments carefully. The results illustrated that the bending strength of the ceramic honeycomb sandwich structure can reach 170 MPa at a relative density of 41.72%. The geometric parameters of the honeycomb core were more critical than the sandwich face-sheet. The cell size, cell wall thickness and cell height were found to be the preferred geometric parameter for justifying the bending resistance performance of the ceramic sandwich panel. Square honeycomb demonstrated better bending performance than the hexagonal honeycomb. This study provides a new basis for further studies on the ceramic lightweight structures.

The cadmium sulphide (CdS) film is grown on cadmium telluride (CdTe) nanorods (NRs) arrays by different methods such as chemical bath deposition (CBD), magnetron sputtering (MS), and homogenous precipitation (HP) techniques. The impact of various deposition methods is explored in detail on the growth of CdTe/CdS composite film, the CdTe/CdS interface property, and solar cell efficiency. Compared to the CBD and HP methods, the MS method can improve the growth of the CdS on CdTe NRs with high crystalline quality. The device based on the CdS film prepared by the MS method demonstrates excellent photovoltaic performance, which has the potential for applications in solar cells.

Vanadium dioxide (VO2) thin films were fabricated by means of DC reactive magnetron sputtering at low temperature, and then were aged in air for 5 years. The thermochromic properties of the fresh VO2 film and aged one were investigated by UV–visible spectrophotometer. The experimental results show that the fresh VO2 film shows excellent thermochromic properties with a high visible transmittance of 40.8% and a large switching efficiency of 73% at 2500 nm. For the film aged in ambient air for 5 years, the visible transmittance is increased to 54.0% due to a blue-shift of absorption edge and a decrease in luminous absorbance. More interestingly, the aged VO2 film still keeps a relatively large switching efficiency of 51% at 2500 nm, suggesting the deposited VO2 film has a good thermochromic stability in ambient air. These characteristics indicate the practical applications of VO2 film to smart optical devices.

The relationship between the doping position of Nb in Bi2Se3 and its superconductivity is investigated by XPS, magnetic measurement and transport measurement. It is found that for NbxBi2Se3, the main impurity phase comes from BiNbSe3. Superconducting volume fraction of Nb doped Bi2Se3 increases with the ratio of Nb inserted in the van der Waals layers. The van der Waals-layer-position doped Nb may lead to superconductivity in Bi2Se3. This work may stimulate further investigation on topological superconductivity mechanism of NbxBi2Se3.

We investigated the physical properties of the cobalt doped layered oxyselenides BiCu1-xCoxSeO. 5% Co doping led to a large increase in the Seebeck coefficient which should be attributed to the magnetic interactions with the magnetic moment carried by Co atoms. The carrier-type of the material is changed from p-type to n-type with 20% Co doping. We studied the thermoelectric property of Bi0.95Ca0.05Cu0.95Co0.05SeO. The dual-doping sample exhibits higher Seebeck coefficient than Ca single doped sample and the ZT was enhanced remarkably. A maximum ZT value of 0.11 was achieved for Bi0.95Ca0.05Cu0.95Co0.05SeO at 300 K.

Honeycomb sandwich structures were widely used in lightweight design. However, the difficulties with the fabrication process actually highly limit their practical usage, especially for ceramic materials. In this paper, 3 mol% yttria-stabilized ZrO2 (3Y-TZP) honeycomb sandwich structures with square and hexagonal cell were prepared successfully by using digital light processing (DLP) printing method. With a base material density of >6.02g/cm3, square/hexagonal honeycomb sandwich structures with structural density of 42.89%-66.24% were achieved by modifying unit cell wall thickness. It can be concluded that square honeycomb cell is preferred for getting higher bending strength at the same structural density.

As a new additive manufacturing method, DLP has the advantages of high precision, fast speed and low cost. ZTA ceramic is anticipated to be used in more applications due to its superior bending strength, fracture toughness and thermal conductivity. But the detailed study with ZTA printing material for DLP is still rarely reported. In this experiment, ZTA ceramic UV resin with various ZrO2 concentration (5-15wt.%) were investigated and tested for their 3D printing performance. ZTA ceramic UV resin with low viscosity (−1) and high solid load (55vol.%) were successfully developed. After sintering at a temperature of ⩾ 1600°C, a relative density of >96% can be always promised. For the optimized doping level of ZrO2 at 11wt%, a density of 99% can be achieved.

Silicon nitride (Si3N4) ceramics are widely used in mechanical and thermal management applications due to their excellent properties. To overcome the difficulties in traditional Si3N4 ceramic forming techniques, it is interesting to see the possibility of making complex-shaped silicon nitride ceramic component with novel 3D printing methods. In this study, we aim to study the effect of photo-initiators on the curing behavior of pre-formulated Si3N4 ceramic UV resin suspension. To elucidate the potential multi-factor interactions, a statistic experiment design was implemented in a sequence of screening and optimization by using Modde software. It was found that the kinds of photo-initiators, total amount of initiators and the mixture ratio between initiators have a great influence on the curing properties of silicon nitride UV ceramic resin. Based on these results, a formula was selected based on the criterion of using least amount photo-initiator while reaching the highest curing thickness.

Compressive strength is one of the most important mechanical properties for cellular ceramics. But the dependence of compressive strength of highly porous cellular ceramic structures on porosity remains unclear due to the limit of available methods for making such strong structures based on specific structural designs. In this paper, the TPMS structures, namely P-cell, and neovius structure, were prepared based on the DLP 3D printing technology. Samples with various unit cells were fabricated with zirconia. The relative density of the sintered samples exceeds 99%. The effects of cell number on the compressive strength and deformation of the model were investigated. Samples with similar relative densities exhibited comparable mechanical property in aspect of compressive strength. It is very interesting that the cell number eventually only influence the total strain.

Cellular structure has been applied in lightweight engineering application because of its high specific strength, high modulus and low relative density. Here we used 3Y-TZP ceramic to realize two typical cellular structures, Kelvin and Octet-truss, through a novel digital light processing (DLP) 3D printing method. The strut size was changed systematically to generate structures with porosities in the range of 10% ∼ 80% and the bending strength of these structures were investigated and analyzed by three-point bending test.

We use neutron powder diffraction to study on the non-superconducting phases of ThFeAsN$_{1-x}$O$_x$ with $x=0.15, 0.6$. In our previous results on the superconducting phase ThFeAsN with $T_c=$ 30 K, no magnetic transition is observed by cooling down to 6 K, and possible oxygen occupancy at the nitrogen site is shown in the refinement(H. C. Mao \emph{et al.}, EPL, 117, 57005 (2017)). Here, in the oxygen doped system ThFeAsN$_{1-x}$O$_x$, two superconducting region ($0\leqslant x \leqslant 0.1$ and $0.25\leqslant x \leqslant 0.55$) have been identified by transport experiments (B. Z. Li \emph{et al.}, J. Phys.: Condens. Matter 30, 255602 (2018)). However, within the resolution of our neutron powder diffraction experiment, neither the intermediate doping $x=0.15$ nor the heavily overdoped compound $x= 0.6$ shows any magnetic order from 300 K to 4 K. Therefore, while it shares the common phenomenon of two superconducting domes as most of 1111-type iron-based superconductors, the magnetically ordered parent compound may not exist in this nitride family., Comment: 4 pages, 4 figures

ThFeAsN$_{1-x}$O$_x$ ($0\leq x\leq0.6$) system with heavy electron doping has been studied by the measurements of X-ray diffraction, electrical resistivity, magnetic susceptibility and specific heat. The non-doped compound exhibits superconductivity at $T_\mathrm{c}^\mathrm{onset}=30$ K, which is possibly due to an internal uniaxial chemical pressure that is manifested by the extremely small value of As height with respect to the Fe plane. With the oxygen substitution, the $T_\mathrm{c}$ value decreases rapidly to below 2 K for $0.1\leq x\leq0.2$, and surprisingly, superconductivity re-appears in the range of $0.25\leq x\leq0.5$ with a maximum $T_\mathrm{c}^\mathrm{onset}$ of 17.5 K at $x=0.3$. For the normal-state resistivity, while the samples in intermediate non-superconducting interval exhibit Fermi liquid behavior, those in other regions show a non-Fermi-liquid behavior. The specific heat jump for the superconducting sample of $x=0.4$ is $\Delta C/(\gamma T_\mathrm{c})=0.89$, which is discussed in terms of anisotropic superconducting gap. The peculiar phase diagram in ThFeAsN$_{1-x}$O$_x$ presents additional ingredients for understanding the superconducting mechanism in iron-based superconductors., Comment: 10 pages, 7 figures

In this work, the TiO 2 -SrTiO 3 hybrids were synthesized by a facile hydrothermal reaction using TiO 2 as the titanium precursor under basic condition. By using the synthesized TiO 2 -SrTiO 3 hybrids as fillers, the films of the TiO 2 -SrTiO 3 /PVDF composites were prepared. The dielectric property and insulation behavior of the films were investigated. High permittivity and improved breakdown strength of the composites were achieved. The breakdown strength of the composites filled with 1 wt% hybrids exhibited an improvement about 80% compared with the unfilled PVDF matrix.

We report neutron diffraction and transport results on the newly discovered superconducting nitride ThFeAsN with $T_c=$ 30 K. No magnetic transition, but a weak structural distortion around 160 K, is observed cooling from 300 K to 6 K. Analysis on the resistivity, Hall transport and crystal structure suggests this material behaves as an electron optimally doped pnictide superconductors due to extra electrons from nitrogen deficiency or oxygen occupancy at the nitrogen site, which together with the low arsenic height may enhance the electron itinerancy and reduce the electron correlations, thus suppress the static magnetic order., 4 pages, 4 figures, Accepted by EPL

Here we report effects of pressure on the recently discovered iron-based superconductor ThFeAsN, the first FeAs-based superconductor containing an actinide element, by in situ high-pressure resistance and synchrotron X-ray diffraction measurements. Our results show that the superconducting transition temperature (T C ) decreases monotonously with increasing pressure and then vanishes at 25.4 GPa. The analysis of the As anion height above the Fe layer ( ), as well as the bond angle of As-Fe-As (α ), for the pressurized ThFeAsN sample found that its T C vs. or α follows the same universal curve describing most of the iron-based superconductors. The results indicate that the lattice parameters also control the superconductivity of the ThFeAsN superconductor, similar to other FeAs-based superconductors, as long as the “superconducting gene” is a FeAs layer. Furthermore, we demonstrate that the ambient-pressure ThFeAsN is an “intrinsic” superconductor, while its lattice structure is not in the optimal state of the FeAs-based superconductors.

The zirconia-toughened-alumina (ZTA) composite powder was exposed to a prior ball milling treatment with a small amount of stearic acid (SA) before the traditional blending process. The effect of different amounts of stearic acid on surface properties of the powder, the particle size distribution of the powder, and the rheological properties of the suspension were systematically studied within the design of experiments. Fourier transformation infrared spectroscopy (FTIR) analysis was used to prove the chemical interaction between the stearic acid and the ZTA powder. The effects of SA content on the particle sizes and their distribution were carefully examined. Rheological properties such as viscosity, yield stress, and power law exponent of the suspensions were determined within a temperature range of 140–170 °C. The optimal content of SA to improve the properties of the suspensions was found to be 3 wt.%.

We report the first nitrogen-containing iron-pnictide superconductor ThFeAsN, which is synthesized by a solid-state reaction in an evacuated container. The compound crystallizes in a ZrCuSiAs-type structure with the space group P4/nmm and lattice parameters a=4.0367(1) {\AA} and c=8.5262(2) {\AA} at 300 K. The electrical resistivity and dc magnetic susceptibility measurements indicate superconductivity at 30 K for the nominally undoped ThFeAsN., Comment: 6 pages, 4 figures, 1 table

The paper pulp compression molding material is one of the most commonly used materials in packing industry. Their mechanical properties attract attentions from professional visitors and researchers. It is a difficult work to test the mechanical properties as the paper pulps are thin, anisotropic and sometimes wet. To spray ink spots with the surface of the specimens is not allowed either. The digit image frequency correlation method (DIFC) is presented in the paper, the information carrier of the displacement is the nature texture on the tested surface. Image acquiring and analysis are accomplished by the CCD camera and computer. From the displacement field strain distributions were obtained and the mechanical properties of the paper pulp compression molding material were evaluated. The test system is simple and the sensitivity is adjustable. DIFC is approved a suitable test method for paper pulp compression molding material.

This paper introduces the studies of self-heat conserving facade panel with abandoned polypropylene fiber. The optimum process conditions were studied. The tensile properties, bending and impact properties of external insulation panel were tested. The results show that when the hot-pressing temperature is 180°C , the tensile, bending and impact of external insulation panel are best. The optimum process is hot-pressing temperature of 180 °C, hot pressure of 10MPa, hot-pressing time 12 Min. The physico-chemical properties were tested. The results show that the data of each test is up to the china national standard .The heat insulation property was tested, the results show that the panels have good insulation performance. The wallboard is light and easy to transport. Because the raw material adopts recycled polypropylene fibers, the price is low and the insulation is good. Recycled fiber-plastic composite is filled with bright future prospects.

Homogeneous microstructure control in the SPS (spark plasma sintering) sintered big size Al2O3 ceramic was realized by the synergy effect of grain boundary tailoring and proper pressure profile design. Two-step pressure profile itself did not show any efficient densification enhancement if no grain boundary modifier MgO added. The two-step pressure profile can effectively reduce average grain size and grain size difference over the sintered specimen, while MgO doping can reduce the average grain size in the whole sintered samples. Finally, a general strategy to overcome the intrinsic temperature gradient in SPS is suggested.

The initiation, propagation and broadening of crazes in polycarbonate were studied with the aid of polarizing microscopy. A loading instrument supplying uniaxial stretch is designed to match polarizing microscopy. With polarizing microscopy, online observations of crazes and stress field can be done simultaneously. Crazes appear in bilateral anteriority of the crack tip and direction of length is perpendicular to the maximum principal stress. Stress on the boarder of the crazing zone is taken as the initiating point of the crazes and length to time of crazes follows exponent law. The initiation, propagation and broadening of crazes is a time-dependent process.

Fine-grained and transparent polycrystalline ruby ceramics (Cr2O3-doped Al2O3) were successfully prepared by spark plasma sintering (SPS). The effect of Cr2O3 concentration on the grain size, hardness, fracture toughness and thermal conductivity of ruby ceramics was investigated systematically. For 0.05 wt.% Cr2O3, high in-line transmittance of 85% at 2000 nm can be reached, further increase of Cr2O3 concentration leads to the decrease in transmittance. High hardness of 23.95–25.05 GPa can be achieved due to the fine grain size in all ruby ceramics. The fracture toughness of 1.9–2.29 MPa m1/2 indicates that no improvement in fracture toughness over pure Al2O3 can be obtained by Cr2O3 doping in these submicron grained ruby ceramics. High thermal conductivity of 28–29.8 W/(m K) at room temperature, close to that of single crystal sapphire, can be achieved. The change in grain size for different Cr2O3 concentrations is the major reason for the change in mechanical and thermal properties, but not for the change in optical properties.

A fully thermal-electrical-mechanical coupled and dynamic finite element model (FEM) is implemented to analyze of the temperature and stress distribution in spark plasma sintering (SPS) process. Th ...

We report the antimony (Sb) doping effect in a prototype system of iron-based supercon-ductors LaFeAsO1-yFy (y=0, 0.1, 0.15). X-ray powder diffraction indicates that the lattice pa-rameters increase with Sb content within the doping limit. Rietveld structural refinements show that, with the partial substitution of Sb for As, while the thickness of the Fe2As2 layers increases significantly, that of the La2O2 layers shrinks simultaneously. So a negative chemical pressure is indeed "applied" to the superconducting-active Fe2As2 layers, in con-trast to the effect of positive chemical pressure by the phosphorus doping. Electrical resis-tance and magnetic susceptibility measurements indicate that, while the Sb doping hardly influences the SDW anomaly in LaFeAsO, it recovers SDW order for the optimally-doped sample of y=0.1. In the meantime, the superconducting transition temperature can be raised up to 30 K in LaFeAs1-xSbxO1-yFy with x=0.1 and y=0.15. The Sb doping effects are discussed in term of both J1-J2 model and Fermi Surface (FS) nesting scenario., Comment: 7 pages, 4 figures, 1 table. to be published in Science in China Series G

A finite element model (FEM) is developed to simulate the temperature distribution in the sample/die/punch assembly during the spark plasma sintering (SPS) process. A thermal–electrical coupled model with temperature dependent thermal and electrical properties is implemented. The simulation studies were conducted using COMSOL and a range of heating-rates and die sizes were considered. Also, both temporary and equilibrium condition during heating process were evaluated in order to express the real temperature development in the sintering. During the spark plasma sintering process, the temperature difference between the sample center and the die surface depend on the heating-rate and die size. The simulation results also revealed that the temperature gradient during the heating process is much bigger than that in the dwelling period. It is necessary to consider the temporary state during the spark plasma sintering process in order to guarantee a well–controlled microstructure, especially in non-conductive ceramic materials.

A two-step pressure profile was used to prepare transparent MgAl2O4 ceramic without sintering aids by spark plasma sintering (SPS) at 1300 degrees C for 3 min. The influence of the pressure profile was investigated systematically and the discoloration in the present study was attributed to the dislocation formed during he fast densification in SPS. At low pre-load pressure, 5 MPa, with the normal characteristic fast heating rate (100 degrees C min(-1)), high inline transmittance of 51% at 550 nm and 85% at 2000 nm can be achieved. Keywords: Sintering; Oxide; Optical transmission; Dislocation; Ultrafine-grained microstructure