Kim, Il-HwanKim, Il-HunIm, Sok-GilJang, Kum-Ok...
10页查看更多>>摘要：The theoretical temperature-concentration-electric field (T -x -E) phase diagram of (1-x)Pb(Mg1/3Nb2/3)O-3- xPbTiO(3) (PMN-PT) is investigated under the electric fields applied along the [001], [011] and [111] directions in the pseudo-cubic coordinate. Using the structurally stable tenth-order Landau-Ginzburg-Devonshire potential model, different two-dimensional sections of T -x -E phase diagram such as T -x (E-[001] = E-[101] = 0.1, 1kV/?) and E-T (x = 0.26, 0.28, 0.3, 0.32, 0.34, 0.36 and 0.38) phase diagrams, and T-x-E-[001] one are constructed for PMNPT single crystals. Also, based on the phenomenological results for T-x-E phase diagram, the features of symmetry changes from high symmetry phase, cubic one, to low symmetry phases, rhombohedral, tetragonal, orthorhombic, monoclinic and triclinic ones, possible during the phase transitions occurring at different temperatures, concentrations and electric fields in PMN-PT single crystals are predicted. The anomalies in dielectric and piezoelectric coefficients accompanied with the symmetry changes are studied. The topological features of T-x-E phase diagram of PMN-PT single crystals are qualitatively in good agreement with those of different piezo/ ferroelectrics (BaTiO3, KNbO3, (1-x)Pb(Zn1/3Nb2/3)O-3-xPbTiO(3) (PZN-PT)) in which the symmetry of order parameter is characterized by the image-group Im gamma(-)(4)= m3m of the irreducible representation gamma(- )(4)of the space group Pm3m as in PMN-PT single crystals.
原文链接:
NSTL
Elsevier
Saito, TetsujiKamishima, SoichiroNishio-Hamane, Daisuke
4页查看更多>>摘要：The substitution of Co for Fe in the Fe2TiSn Heusler compound resulted in a change in the magnetic properties. Although the Fe2TiSn and Fe2-xCoTiSn (x = 0.5-1.0) Heusler compounds were paramagnetic, the Fe2-xCoTiSn (x = 1.5-2.0) Heusler compounds were found to be ferromagnetic. The Fe2TiSn Heusler compound is a p-type thermoelectric material that has a positive Seebeck coefficient of 30 mu V/K at room temperature. On the other hand, Co-substituted (Fe,Co)(2)TiSn Heusler compounds prepared in the present study were shown to be n-type thermoelectric materials, regardless of the Co content. The (Fe,Co)(2)TiSn Heusler compounds exhibited relatively low electrical resistivity values, ranging from 1.71 mu omega m for the Co2TiSn compound to 11.5 mu omega m for the Fe1.5Co0.5TiSn compound. It was found that the power factor of the Co2TiSn Heusler compound (647 mu W/mK(2) at room temperature) was more than double that of the Fe2TiSn Heusler compound.
原文链接:- NSTL
- Elsevier
Hassan, Dhia A.Sultan, H. A.Al-Asadi, Rafid H.Hassan, Qusay M. A....
13页查看更多>>摘要：The molecular structure of mercurated azo compound (A1), (E)-(2-((8-hydroxyquinolin-5-yl)diazenyl)-5-sulfamoylphenyl)mercury(II) chloride, is investigated theoretically by the DFT with the GGA approximation, PEB level and DNP as basis set. The nonlinear optical (NLO) properties of the synthesized azo compound are investigated using a continuous wave (cw), low power, with TEM00 mode laser beam using the methods diffraction ring patterns (DRPs) and Z-scan. The nonlinear refraction index (NRI) is calculated based on both methods where as high as 5.28 x 10(-7 )cm(2)/W of the NRI is determined via the DRPs. The optical limiting (OLg) property of the A1 compound is examined with limiting threshold of 10 mW is determined. The experimentally determined DRPs are simulated via Fresnel-Kirchhoff integral with good accord of experimental and theoretical results.
原文链接:- NSTL
- Elsevier
Hong, YuantingWei, QinLiang, XinLu, Wenjian...
6页查看更多>>摘要：We study the origin of charge density wave (CDW) in rare-earth tritelluride LaTe3 and the strain tuning effect on CDW in monolayer LaTe3 by first-principles calculations. The calculations of the electronic structure, phonon spectrum, electron susceptibility, and electron-phonon coupling (EPC) matrix show that the origin of CDW in LaTe3 is momentum-dependent EPC rather than Fermi-surface nesting. The unidirectional CDW with a wavevector QCDW 2/7c* is the most stable state. We study the biaxial strain effect on CDW in monolayer LaTe3 by evaluating the total energy, CDW-related lattice distortions, and phonon spectra. Our results show that the tensile strain can enhance CDW order, while the compressive strain can inhibit CDW order. As the CDW order is fully suppressed, superconductivity could be induced. Our study may help to clarify the mechanism of CDW in LaTe3 and find the effective tuning method of CDW in monolayer or few-layer configuration.
原文链接:- NSTL
- Elsevier
Wu, Meng-XinWang, PengKuang, An-LongXua, Xiao-Hui...
10页查看更多>>摘要：The structural and electronic properties of I4/mmm XSi2 (X = Cr, Mo and W) are systematically studied by first-principles calculation. First, the dynamical stability of XSi2 (X = Cr, Mo and W) is verified by the phonon spectrums, the thermal stability is confirmed by the ab initio molecular dynamics simulations (AIMD) at 300 K and the mechanical stability is affirmed by the calculated elastic constants. Electronic structure computations uncover the clear drum-head-like surface states and the topological nodal lines (TNLs) which are close to the Fermi level E-F and gamma centered in the Brillouin zone (BZ). Further investigations indicate the band structures and the TNLs are robust against the spin-orbit coupling (SOC), the biaxial and uniform strains, which is beneficial to experimental observation. Our results suggest tetragonal CrSi2, MoSi2 and WSi2 are ideal transition metal sili-cides to study the TNLs and drum-head-like surface states for topological physics.
原文链接:- NSTL
- Elsevier
Luo, MingqiuTong, PeiqingFu, Hao
8页查看更多>>摘要：Lieb-Robinson bound (LRB) in one-dimensional noninteracting many-electron systems with the disordered and quasiperiodic on-site potentials is studied numerically. For the short-range hopping system, a logarithmic light cone (i.e. |x| = beta log t + x(0)) is found in the system with the disordered on-site potential for small time. The coefficient fi decreases with the increasing strength of disordered. When time is large, the bound does not change with time (i.e. |x| = C). For the generalized Fibonacci quasiperiodic (GFQ) system, the on-site potential is taken as V or -V according to two kinds of GFQ sequences. It is found that the system has a power-law light cone (i.e. |x| proportional to t(gamma), with 0 < gamma < 1). The exponent gamma decreases with the increasing V. We also find that gamma for the first class of GFQ system is larger than that for the second class of GFQ system with the same V. Finally, the effects of the long-range hopping which decays like r(-alpha) with the distance r on LRB are discussed.
原文链接:- NSTL
- Elsevier
Omugbe, E.Osafile, O. E.Nenuwe, O. N.Enaibe, E. A....
9页查看更多>>摘要：The electronic and thermoelectric properties of two-dimensional Yttrium carbide MXenes (Y2CT2, T = F, Br, OH, H), Y2CClH and Y2CFH are studied by first-principle calculations within the density functional theory and Boltzmann theory respectively. The results of the electronic structure revealed that the MXenes possess energy gaps (0.47 - 1.17eV) making them semiconductors. At the temperatures T = 100 K and 400 K, the MXenes attain high and moderate figures of merit and Seebeck coefficients near the band edges with Y2CH2 having the largest value of ZT = 0.97, which can be compared to 10% Carnot cycle efficiency. Generally, the MXenes support chemical stability owing to the negative values of the formation energies which may indicate the feasibility of fabricating them experimentally. Our results indicate that the Yttrium carbide-based MXenes are potential thermoelectric materials at low and moderate temperatures.
原文链接:- NSTL
- Elsevier
Wei, Xiao-PingLiu, Jun-RuiZhang, XinChang, Wen-Li...
6页查看更多>>摘要：In our previous works [Liu et al. (2022)], the quaternary Heusler alloy CrLaCoAl had been predicted to be half metallic ferrimagnet with high Curie temperature, and it met the dynamic, mechanical and thermal stabilities. Furthermore, a smaller convex hull indicated that it was likely to be prepared in experiment. Therefore, we constructed the slab model of CrLaCoAl (100) surface to investigate its surface effect against stability, electronic and magnetic properties. Results showed that the AlAl termination had the lowest surface energy in all terminations. Atomic relaxation exhibited that different atoms on the termination surface stretched to different degrees, leading in the changes of distance between the atoms on the surface, which in turn changed the hybridization between them, and also affected the magnetic moments of atoms. Overall, our research may offer some valuable hints for CrLaCoAl alloy prepared as a thin film or multilayer with high polarization.
原文链接:- NSTL
- Elsevier
Nikoghosyan, H. S.Nikoghosyan, G.Demirchian, H. G.
6页查看更多>>摘要：The features of the manifestation of the self-induced transparency (SIT) effect at intersubband resonance in the inversion n- layer of silicon semiconductor systems (in field-effect transistors (100)Si - MOSFET) are analyzed. The course of the interaction of ultrashort laser pulses with the quantum states of the inversion layer of the MOS structure varies, depending on the concentration of the induced charge, by changing the voltage across the metal gate. The evolution of a pulse in the transient stage of deformation as it propagates in a resonant medium of an inversion channel is discussed. Possible consequences for a non-degenerate one-photon resonance are considered, with controlled changes in the detuning between a fixed pulse frequency and the resonant energy of the intersubband transition, caused by changes in the charge density. The parametric dependence on the concentration of the induced charges in the "area theorem" for the propagation process in the inversion channel is revealed.
原文链接:- NSTL
- Elsevier
