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Understanding the chemical states and electronic states of superconducting materials can help researchers to grasp their superconducting mechanisms. Then, through doping, high pressure or other methods, the T c (Critical Temperature) can be boosted. Recently, a new layered carbide superconductor ThMo2Si2C was discovered. Its chemical states and electronic states are unknown. Here, the chemical states of ThMo2Si2C are investigated using X-ray photoelectron spectroscopy assisted with argon ion sputtering and Raman spectroscopy. The physical significance behind them is elucidated. Its electronic states are investigated by first-principles calculations. It is found that the major contribution to the total DOS (Density of States) is from Mo 4d state, which plays the dominant role in the superconductivity of ThMo2Si2C. The hybridization between Th 6d and Mo 4d is very weak. Thus, a separation of the structure into independent Mo-C-Si and Th subunits (layers) is justified from the point of view of electronic structure. A flat band along the A-M high-symmetry direction is observed near the Fermi level. The influence of the interlayer distance between Mo-C-Si units (layers) on the DOS and band structure is investigated by first-principles calculations too.

Solid oxide fuel cells (SOFCs) have been regarded as promising eco-friendly power sources in recent years owing to their high energy conversion efficiency and fuel flexibility. La2Mo2O9-based ceramics draw researchers’ attention due to their good performance as electrolyte materials for SOFCs. In this study, the Sm and Al co-doped La2Mo2O9, La2-xSmxMo1.8Al0.2O8.7 (x=0.1,0.2,0.3 and 04, LSMAO), are successfully synthesized by the sol-gel method as electrolyte materials for SOFCs. The phase evolution, sintering, the microstructural and electrochemical performance of LSMAO were observed by TG-DSC, XRD, SEM, and impedance analyses, respectively. The results show that the highly phase-pure cubic LSMAO nanopowders can be obtained after calcining at 600 °C for 2 h. The as-synthesized LSMAO powders exhibited a better sintering activity. All these samples were found to have a relative density above 94.5% after sintering at 950 °C for 5 h. The electrical performance study shows that higher doping concentrations of Sm caused a decrease in ionic conductivity and an increase in activation energy. La1.9Sm0.1Mo1.8Al0.2O8.7 exhibited the highest oxide ionic conductivity (σ800 °C=0.033 S/cm) and lowest electrical activation energy (Ea=0.85 eV). This shows that LSMAO could be used as a potential electrolyte for intermediate temperature SOFCs (IT-SOFCs).

In this paper, the millimeter wave radar amplification device is designed using the MWG303 power amplifier chip of Milliway Electronic Technology Co., Ltd. The whole device comprises an input waveguide microstrip transition structure based on Rogers 5880 and an output waveguide microstrip transition structure based on quartz. And waveguide structures such as waveguide turn and waveguide lift, in this design, the waveguide microstrip transition circuit is designed and simulated in the 3D electromagnetic field simulation software HFSS of Ansoft Company, and then the parts are combined, and the micro-assembly test is carried out after CAD processing. The results show that the gain can reaches more than 10dB. The design has the advantages of high gain, good flatness, practical structure and so on.

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.

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

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.

CaCu3Ti4O12 ceramic samples sintered at different temperatures were studied by measurements of microstructural and dielectric properties. Electron microscopy for thermally-etched samples confirmed a microstructure with subgrains (SG) buried in a crystalline grain. The detailed dielectric properties were shown to be conformable with the double-barrier-layer capacitance model. The complex electric modulus analysis revealed unambiguously each contribution of the SG interiors, SG boundaries and grain boundaries to the dielectric constant. Our result clarified how the dielectric properties change with increasing sintering temperature. It was concluded that grain boundaries rather than SG boundaries played the key role in the low-frequency giant dielectric constant in CCTO ceramics.

We report the synthesis and physical properties of a nickel-based arsenide ThNiAsN. The new compound crystallizes in a ZrCuSiAs-type structure (space group ) with lattice parameters and . Bulk superconductivity at is demonstrated by the measurements of electrical resistivity, dc magnetic susceptibility, and heat capacity. The upper critical field at zero temperature, , and the specific-heat jump at T c are 6.1 T and , respectively. These two physical quantities, together with the T c value, are the highest among the Ni-based ZrCuSiAs-type materials. We discuss this enhanced superconductivity in terms of the internal chemical pressure in ThNiAsN.

The isovalent substitution effect of Ru in CeFe1−xRuxAsO (0 ⩽ x ⩽ 1) has been systematically studied by powder X-ray diffraction, electrical resistivity, magnetization, and specific heat measurements. The antiferromagnetic (AFM) ordering of both d and 4f electrons are suppressed upon Ru doping, followed by Pauli paramagnetism (d electrons) and local moment paramagnetism (4f electrons) with strong ferromagnetic fluctuation, respectively. Neither superconductivity above 2 K nor pronounced Kondo screening are observed in the substitution phase diagram. Combined with published results of the cerium-based quaternary compounds CeMXO(M = Fe, Ru; X = P, As), our data suggest that the end member CeRuAsO is on the verge of becoming an FM Kondo lattice. Meanwhile, the ground state of 4f electrons in the quaternary CeMXO system should be determined by both the interlayer d-f Kondo coupling (JKondo) and the intralayer Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction (JRKKY ), which are both very sensitive to the change in crystal structure.

The results of x-ray diffraction, electrical resistivity, magnetic susceptibility, and (57)Fe and (155)Gd Mössbauer spectroscopy studies of polycrystalline samples of nonsuperconducting GdFeAsO and superconducting Gd(0.84)Th(0.16)FeAsO are reported. The superconductor Gd(0.84)Th(0.16)FeAsO has the onset transition temperature of 54.4(1) K. We find that Fe and Gd magnetic moments in GdFeAsO order antiferromagnetically at 132.7(1) K and 4.1(1) K, respectively. In Gd(0.84)Th(0.16)FeAsO, Fe atoms carry no magnetic moment down to 1.9 K whereas Gd magnetic moments order below 2.9(1) K. This is taken as evidence for the coexistence of Gd magnetic order and superconductivity. The Debye temperatures of GdFeAsO and Gd(0.84)Th(0.16)FeAsO are, respectively, 409(4) and 389(3) K.

Following the discovery of superconductivity in an iron-based arsenide LaO1-xFxFeAs with a superconducting transition temperature (Tc) of 26 K[1], Tc was pushed up surprisingly to above 40 K by either applying pressure[2] or replacing La with Sm[3], Ce[4], Nd[5] and Pr[6]. The maximum Tc has climbed to 55 K, observed in SmO1-xFxFeAs[7, 8] and SmFeAsO1-x[9]. The value of Tc was found to increase with decreasing lattice parameters in LnFeAsO1-xFx (Ln stands for the lanthanide elements) at an apparently optimal doping level. However, the F- doping in GdFeAsO is particularly difficult[10,11] due to the lattice mismatch between the Gd2O2 layers and Fe2As2 layers. Here we report observation of superconductivity with Tc as high as 56 K by the Th4+ substitution for Gd3+ in GdFeAsO. The incorporation of relatively large Th4+ ions relaxes the lattice mismatch, hence induces the high temperature superconductivity., 4 pages, 3 figures