[en] In this paper, parameters of site soils based on the new seismic code are adopted and the stochastic ground motion generation method based on the modified YX Hu-XY Zhou model is used to generate reasonable and reliable artificial seismic waves, which proved to have obvious statistical characteristics and can meet the requirements of seismic wave selection. The improved genetic algorithm and the probability density evolution method (PDEM) are combined to optimize the response and reliability of a TMD-structure under the obtained artificial wave excitations. Several examples were given to verify the correctness of the proposed methods, as well as several conclusions were drawn. (paper)

[en] We report the high temperature transport and thermoelectric properties of Ca_1-xR_xMnO₃(R = La, Y and Ce) perovskites in the electron-doped range. The substitution of different valence ions has a similar effect on the thermoelectric properties of this system. Resistivity and thermopower change regularly as the enhancement of doping level; they are both determined mainly by electron concentration. Thermal conductivity is dependent mainly on the weight of R ions, and it decreases monotonically with increasing doping content. The optimal electron concentration is around 0.1-0.12 for thermoelectric performance; in this range the ZT value of Ca_0.9La_0.1MnO₃ exceeds 0.12 at 1000 K, exhibiting a good high temperature thermoelectric applied potential. Besides, the hopping nature of the charge carriers is well explained in the framework of polaron theory. The high temperature thermopower values which are inconsistent with nominal Mn³⁺ ion t_2g³ e_g¹ configuration are also discussed.

[en] In this study, the transport and magnetic properties of electron-doped perovskites R_xCa_1-xMnO₃ (R = La, Y and Ce) were investigated. As the R ion content increases, the crystal structure, resistivity, magnetoresistance, magnetization and related characteristic temperature of these systems all vary systematically. The data show that the variations in the electrical transport properties are mainly dependent on carrier concentration, whereas the magnetic properties of these systems are also dependent on crystal structure. When the carrier concentration exceeds a certain level, charge ordering occurs, leading to the localized electronic state and peaks in the magnetization curves. The magnetic transition temperature T_N can be well described by crystal structural parameters, suggesting that crystal structure and magnetic properties are strongly coupled to each other.

[en] We report measurements of electrical resistivity, thermopower and thermal conductivity for a series of high-textured Ag-doped and Ag-added Ca₃Co₄O_9+δ ceramic specimens. The results show that variable range hopping transport behaviour of the system transforms from two-dimensional to quasi-three-dimensional with Ag addition, which is isotropic to a certain extent. The thermoelectric (TE) performance of Ca₃Co₄O_9+δ is improved effectively by Ag⁺ doping or/and Ag addition. The Ca_2.7Ag_0.3 Co₄O_9+δ/Ag_0.3 composite exhibits quite a respectable room temperature ZT value of 0.1, suggesting that such a composite is a promising candidate for p-type room temperature TE cooling application

[en] The structural properties, electronic band structure and Bader charge of Sb₂Te₃ under hydrostatic pressure were simulated using density functional theory in order to study isostructural phase transitions (IPT) in Sb₂Te₃. The theoretical results showed that the axial ratio c /a did not exhibit any anomaly below 6 GPa. The variations of bond lengths were discontinuous at 2.5 GPa, which suggested considerable changes in interatomic interactions and provided sound support to the IPT. The effective charges of Sb and Te atoms showed significant discontinuous variations at 2.5 GPa, which revealed a strong redistribution of the electronic charge density and considerably changed interactions among bonding atoms. Thus, the IPT is originated from the considerable variation in the electronic charge density. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] Highlights: • A new compound based on the solid solution of BiFeO_3–GdCrO_3 were synthesized. • The structure–property relationship of the system was studied. • Enhanced multiferroic properties were obtained in 0.9BiFeO_3–0.1GdCrO_3. • The present materials allow us to further develop multiferroic components of BiFeO_3. - Abstract: Solid solutions of perovskites (1−x)BiFeO_3–xGdCrO_3 (x = 0, 0.1 and 0.2) has been synthesized under high-pressure conditions in an attempt to find magnetoelectric materials. Structural studies of these samples show a compositional-driven phase transition from rhombohedral for x = 0 to orthorhombic symmetry for x = 0.2, with a mixture of the two phases for x = 0.1. Magnetic and ferroelectric properties of these samples are shown to correlate with evolution of their structural state. The addition of GdCrO_3 in BiFeO_3 leads to a ferroelectric–paraelectric phase transition. The magnetic properties of BiFeO_3 are improved due to structural distortion and partial destruction of spiral spin structure caused by introducing GdCrO_3. The best combination of multiferroic characteristics, with remanent polarization and magnetization of 10.1 μC/cm"2 and 0.118 emu/g, respectively, was realized in the sample with x = 0.1. The magnetodielectric and magnetoelectric effect of these samples were evaluated

[en] Based on fluid equations, we show a time-dependent self-consistent nonlinear model for void formation in magnetized dusty plasmas. The cylindrical configuration is applied to better illustrate the effects of the static magnetic field, considering the azimuthal motion of the dusts. The nonlinear evolution of the dust void and the rotation of the dust particles are then investigated numerically. The results show that, similar to the unmagnetized one-dimensional model, the radial ion drag plays a crucial role in the evolution of the void. Moreover, the dust rotation is driven by the azimuthal ion drag force exerting on the dust. As the azimuthal component of ion velocity increases linearly with the strength of the magnetic field, the azimuthal component of dust velocity increases synchronously. Moreover, the angular velocity gradients of the dust rotation show a sheared dust flow around the void. (authors)

[en] Magnetic entropy change and refrigerant capacity in applied magnetic fields up to 5 T have been investigated for the single crystalline YbTiO_3. The maximal magnetic entropy changes at the second order magnetic phase transition temperature T_C (42 K) are about 2.47 and 5.25 J kg⁻¹ K⁻¹ under 1.5 and 5 T, respectively. The magnetic entropy change is attributed to the sharp magnetization jump, related with anomalies of the lattice parameters just at the Curie temperature. The magnetic entropy change for YbTiO₃ can be well described by a phenomenological universal curve behavior. The field dependence of the magnetic entropy change and the relative cooling power was also studied. From the analysis of the relationship between the local exponent n and the critical exponents, we conclude that the critical behavior of YbTiO₃ belongs to the three-dimensional Heisenberg class, which was also confirmed by the heat capacity measurement.

[en] Photoluminescence (PL) of WS₂ monolayer has attracted attention triggered by potential optoelectronic and photoelectric applications due to the largest direct band gap in WS₂ monolayer among transition metal dichalcogenides. The PL of WS₂ monolayer is dominated by charged excitons (trions) and bound excitons, which suppress the luminescence of free excitons. Herein, we report a one-step growth of a nanosheet/nanoparticles hybrid structure to reduce the emission of bound excitons and trions in WS₂ monolayer by surface passivation with WO₃ nanoparticles. Peak positions of the PL spectra in WS₂ monolayers depend on the density of WO₃ nanoparticles on their surface. With increasing density of WO₃ nanoparticles, the PL of WS₂ monolayers experiences the transition from bound excitons and charged excitons (trions) to neutral excitons. These results suggest that the engineering of PL of WS₂ monolayers may be realized by surface passivation using nanoparticles of wide band gap semiconductors. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] Oxygen functional groups are one of the most important subjects in the study of electrochemical properties of carbon materials which not only can change the wettability, conductivity and pore size distributions of carbon materials, but also can occur redox reactions. In the electrode materials of carbon-based supercapacitors, the oxygen functional groups have been widely used to improve the capacitive performance. In this paper, we systematically analyzed the reasons for the increase of the capacity that promoted by oxygen functional groups in the charge∕discharge cycling tests and the mechanism how the pseudocapacitance is provided by the oxygen functional groups in the acid/alkaline aqueous electrolyte. In addition, we in more depth discussed the effect of the oxygen functional groups in electrochemical impedance spectroscopy.