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The structures, the martensitic transformations, and the magnetic properties are studied systematically in Mn50Ni40−xCuxIn10, Mn50−xCuxNi40In10, and Mn50Ni40In10−xCux alloys. The partial substitution of Ni by Cu reduces the martensitic transformation temperature, but has little influence on the Curie temperature of austenite. Comparatively, the martensitic transformation temperature increases and the Curie temperature of austenite decreases with the partial replacement of Mn or In by Cu. The magnetization difference between the austenite phase and the martensite phase reaches 70 emu/g in Mn50Ni39Cu1In10; a field-induced martensite-to-austenite transition is observed in this alloy. [ABSTRACT FROM AUTHOR]

The tunneling between double wells of atom in crossed electromagnetic fields is investigated by a one-dimensional Hamiltonian model. The crossed fields induced outer well is apart from the nuclear origin and it is very difficult to access by means of spectroscopy but it will be possible if there exists the tunneling of the electron between the outer well and the Coulomb potential predominated well at the nuclear origin. A one-dimensional quantum calculation with B-spline basis has been performed for hydrogen atom in crossed fields accessible in our laboratory, at B = 0.8 T and F = [?]220 V*cm[?]1. The calculation shows that the wavefunctions of some excited states close to the Stark saddle point in the outer well extend over to the Coulomb potential well, making it possible to penetrate the quantum information of the outer well. However, the tunneling rate is very small and the spectral measurement of the transitions from the ground state should be of a high resolution and high sensitivity. [ABSTRACT FROM AUTHOR]

A modified sol-gel method is used for synthesizing Nd ion doped lead zirconate titanate nanopowders Pb1-3x/2NdxZr0.52Ti0.48O3 (PNZT) in an ethylene glycol system with zirconium nitrate as zirconium source. The results show that it is critical to add lead acetate after the reaction of zirconium nitrate with tetrabutyl titanate in the ethylene glycol system for preparing PNZT with an exact fraction of titanium content. It has been observed that the dopant of excess Nd ions can effectively improve the sintered densification and activity of the PNZT ceramics. Piezoelectric, dielectric and ferroelectric properties of the PNZT ceramics are remarkably enhanced as compared with those of monolithic lead zirconate titanate (PZT). Especially, the supreme values of piezoelectric constant (d33) and dielectric constant ([?]) for the PNZT are both about two times that of the monolithic PZT and moreover, the remnant polarization (Pr) also increases by 30%. According to the analysis of the structures and properties, we attribute the improvement in electrical properties to the lead vacancies caused by the doping of Nd ions. [ABSTRACT FROM AUTHOR]

A single-phase iron oxide Ba0.8Sr0.2FeO3-δ with a simple cubic perovskite structure in Pm-3m symmetry is successfully synthesized by a solid-state reaction method in O2 flow. The oxygen content is determined to be about 2.81, indicating the formation of mixed Fe3+ and Fe4+ charge states with a disorder fashion. As a result, the compound shows small-polaron conductivity behavior, as well as spin glassy features arising from the competition between the ferromagnetic interaction and the antiferromagnetic interaction. Moreover, the competing interactions also give rise to a remarkable exchange bias effect in Ba0.8Sr0.2FeO2.81, providing an opportunity to use it in spin devices. [ABSTRACT FROM AUTHOR]

The phase evolution of Bi-2223 precursor powder prepared by spray pyrolysis method is studied with different heat treatment parameters. The results show that the reaction temperature and phase composition of precursor powder depend on heat treatment atmosphere. Phase assemblage of (Bi,Pb)-2212, AEC, CuO, and small Bi-2201 can be obtained by heat-treated in N2-0.1%O2 atmosphere. For precursor powder, there is sufficient reaction process at 770 °C, and the dimension of Bi-2212 phase increases rapidly with the increase of heat treatment temperature and time. The dimension of AEC phase also increases by extending heat treatment time. As a balance among phase assemblage, dimension of particle and adequate reaction, a reasonable precursor powder can be obtained by heat-treated at 770 °C for 12 h–16 h in N2-0.1%O2 atmosphere. Critical current of 37-filament Bi-2223 tape is about 120 A, which confirms that these heat treatment parameters are reasonable. [ABSTRACT FROM AUTHOR]

In order to clarify the influence of methane concentration and deposition time on self-organized nano-multilayers, three serial copper–carbon films have been prepared at various methane concentrations with different deposition times using a facile magnetron sputtering deposition system. The ratios of methane concentration (CH4/Ar+CH4) used in the experiments are 20%, 40%, and 60%, and the deposition times are 5 minutes, 20 minutes, and 40 minutes, respectively. Despite the difference in the growth conditions, self-organizing multilayered copper–carbon films are prepared at different deposition times by changing methane concentration. The film composition and microstructure are investigated by x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). By comparing the composition and microstructure of three serial films, the optimal growth conditions and compositions for self-organizing nano-multilayers in copper–carbon film are acquired. The results demonstrate that the self-organized nano-multilayered structure prefers to form in two conditions during the deposition process. One is that the methane should be curbed at low concentration for long deposition time, and the other condition is that the methane should be controlled at high concentration for short deposition time. In particular, nano-multilayered structure is self-organized in the copper–carbon film with copper concentration of 10–25 at.%. Furthermore, an interesting microstructure transition phenomenon is observed in copper–carbon films, that is, the nano-multilayered structure is gradually replaced by a nano-composite structure with deposition time and finally covered by amorphous carbon. [ABSTRACT FROM AUTHOR]

The structures and elasticities of phase B silicates with different water and iron (Fe) content are obtained by first-principles simulation to understand the effects of water and Fe on their properties under high pressure. The lattice constants a and b decrease with increasing water content. On the contrary, c increases with increasing water content. On the other hand, the b and c decrease with increasing Fe content while a increases with increasing Fe content. The decrease of M (metal)–O octahedral volume is greater than the decrease of SiO polyhedral volume over the same pressure range. The density, bulk modulus and shear modulus of phase B increase with increasing Fe content and decrease with increasing water content. The compressional wave velocity (Vp) and shear wave velocity (Vs) of phase B decrease with increasing water and Fe content. The comparisons of density and wave velocity between phase B silicate and the Earth typical structure provide the evidence for understanding the formation of the X-discontinuity zone of the mantle. [ABSTRACT FROM AUTHOR]

A new oxide CaCr0.5Fe0.5O3 was prepared under high pressure and temperature conditions. It crystallizes in a B-site disordered Pbnm perovskite structure. The charge combination is determined to be Cr5+/Fe3+ with the presence of unusual Cr5+ state in octahedral coordination, although Cr4+ and Fe4+ occur in the related perovskites CaCrO3 and CaFeO3. The randomly distributed Cr5+ and Fe3+ spins lead to short-range ferromagnetic coupling, whereas an antiferromagnetic phase transition takes place near 50 K due to the Fe3+–O–Fe3+ interaction. In spite of the B-site Cr5+/Fe3+ disorder, the compound exhibits electrical insulating behavior. First-principles calculations further demonstrate the formation of charge combination, and the electron correlation effect of Fe3+ plays an important role for the insulting ground state. CaCr0.5Fe0.5O3 provides the first Cr5+ perovskite system with octahedral coordination, opening a new avenue to explore novel transition-metal oxides with exotic charge states. [ABSTRACT FROM AUTHOR]

Elastic properties of three high pressure polymorphs of CaCO3 are investigated based on first principles calculations. The calculations are conducted at 0 GPa–40 GPa for aragonite, 40 GPa–65 GPa for post-aragonite, and 65 GPa–150 GPa for the -h-CaCO structure, respectively. By fitting the third-order Birch–Murnaghan equation of state (EOS), the values of bulk modulus and pressure derivative are 66.09 GPa and 4.64 for aragonite, 81.93 GPa and 4.49 for post-aragonite, and 56.55 GPa and 5.40 for -h-CaCO, respectively, which are in good agreement with previous experimental and theoretical data. Elastic constants, wave velocities, and wave velocity anisotropies of the three high-pressure CaCO phases are obtained. Post-aragonite exhibits 25.90%–32.10% anisotropy and 74.34%–104.30% splitting anisotropy, and -h-CaCO shows 22.30%–25.40% anisotropy and 42.81%–48.00% splitting anisotropy in the calculated pressure range. Compared with major minerals of the lower mantle, CaCO high pressure polymorphs have low isotropic wave velocity and high wave velocity anisotropies. These results are important for understanding the deep carbon cycle and seismic wave velocity structure in the lower mantle. [ABSTRACT FROM AUTHOR]

Phase H (MgSiOH, one of the dense hydrous magnesium silicates (DHMSs), is supposed to be vital to transporting water into the lower mantle. Here the crystal structure, elasticity and Raman vibrational properties of the two possible structures of phase H with Pm and symmetry under high pressures are evaluated by first-principles simulations. The cell parameters, elastic and Raman vibrational properties of the Pm symmetry become the same as the symmetry at GPa. The symmetrization of hydrogen bonds of the Pm symmetry at GPa results in this structural transformation from Pm to . Seismic wave velocities of phase H are calculated in a range from 0 GPa to 100 GPa and the results testify the existence and stability of phase H in the lower mantle. The azimuthal anisotropies for phase H are , ( symmetry) and , ( symmetry) at 0 GPa, and increase to , ( symmetry) and , (Pm symmetry) at 30 GPa. The maximum direction for phase H is [101] and the minimum direction is [110]. The anisotropic results of seismic wave velocities imply that phase H might be a source of seismic anisotropy in the lower mantle. Furthermore, Raman vibrational modes are analyzed to figure out the effect of symmetrization of hydrogen bonds on Raman vibrational pattern and the dependence of Raman spectrum on pressure. Our results may lead to an in-depth understanding of the stability of phase H in the mantle. [ABSTRACT FROM AUTHOR]

An expression of degree of polarization (DOP) for metallic material is presented based on the three-component polarized bidirectional reflectance distribution function (pBRDF) model with considering specular reflection, directional diffuse reflection and ideal diffuse reflection. The three-component pBRDF model with a detailed reflection assumption is validated by comparing simulations with measurements. The DOP expression presented in this paper is related to surface roughness, which makes it more reasonable in physics. Test results for two metallic samples show that the DOP based on the three-component pBRDF model accords well with the measurement and the error of existing DOP expression is significantly reduced by introducing the diffuse reflection. It indicates that our DOP expression describes the polarized reflection properties of metallic surfaces more accurately. [ABSTRACT FROM AUTHOR]

We study the photon statistics of pulse-pumped four-wave mixing in fibers with weak coherent signal injection by measuring the intensity correlation functions of individual signal and idler fields. The experimental results show that the intensity correlation function of individual signal (idler) field decreases with the intensity of signal injection. After applying narrow band filter in signal (idler) band, the value of decreases from 1.9 ± 0.02 (1.9 ± 0.02) to 1.03 ± 0.02 (1.05 ± 0.02) when the intensity of signal injection varies from 0 to 120 photons/pulse. The results indicate that the photon statistics changes from Bose–Einstein distribution to Poisson distribution. We calculate the intensity correlation functions by using the multi-mode theory of four-wave mixing in fibers. The theoretical curves well fit the experimental results. Our investigation will be useful for mitigating the crosstalk between quantum and classical channels in a dense wavelength division multiplexing network. [ABSTRACT FROM AUTHOR]

In this work, temperature dependences of small-signal model parameters in the SiGe HBT HICUM model are presented. Electrical elements in the small-signal equivalent circuit are first extracted at each temperature, then the temperature dependences are determined by the series of extracted temperature coefficients, based on the established temperature formulas for corresponding model parameters. The proposed method is validated by a 1 × 0.2 × 16 μm2 SiGe HBT over a wide temperature range (from 218 K to 473 K), and good matching is obtained between the extracted and modeled results. Therefore, we believe that the proposed extraction flow of model parameter temperature dependence is reliable for characterizing the transistor performance and guiding the circuit design over a wide temperature range. [ABSTRACT FROM AUTHOR]

A GaN/Al0.3Ga0.7N/AlN/GaN high-electron mobility transistor utilizing a field plate (with a 0.3 um overhang towards the drain and a 0.2 um overhang towards the source) over a 165-nm sputtered HfO2 insulator (HfO2-FP-HEMT) is fabricated on a sapphire substrate. Compared with the conventional field-plated HEMT, which has the same geometric structure but uses a 60-nm SiN insulator beneath the field plate (SiN-FP-HEMT), the HfO2-FP-HEMT exhibits a significant improvement of the breakdown voltage (up to 181 V) as well as a record field-plate efficiency (up to 276 V/um). This is because the HfO2 insulator can further improve the modulation of the field plate on the electric field distribution in the device channel, which is proved by the numerical simulation results. Based on the simulation results, a novel approach named the proportional design is proposed to predict the optimal dielectric thickness beneath the field plate. It can simplify the field-plated HEMT design significantly. [ABSTRACT FROM AUTHOR]

This paper develops the simple and accurate two-dimensional analytical models for new asymmetric double-gate fully depleted strained-Si MOSFET. The models mainly include the analytical equations of the surface potential, surface electric field and threshold voltage, which are derived by solving two dimensional Poisson equation in strained-Si layer. The models are verified by numerical simulation. Besides offering the physical insight into device physics in the model, the new structure also provides the basic designing guidance for further immunity of short channel effect and drain-induced barrier-lowering of CMOS-based devices in nanometre scale. [ABSTRACT FROM AUTHOR]

We present an AlInN/AlN/GaN MOS--HEMT with a 3 nm ultra-thin atomic layer deposition (ALD) Al2O3 dielectric layer and a 0.3 um field-plate (FP)-MOS--HEMT. Compared with a conventional AlInN/AlN/GaN HEMT (HEMT) with the same dimensions, a FP-MOS--HEMT with a 0.6 um gate length exhibits an improved maximum drain current of 1141 mA/mm, an improved peak extrinsic transconductance of 325 mS/mm and effective suppression of gate leakage in both the reverse direction (by about one order of magnitude) and the forward direction (by more than two orders of magnitude). Moreover, the peak extrinsic transconductance of the FP-MOS--HEMT is slightly larger than that of the HEMT, indicating an exciting improvement of transconductance performance. The sharp transition from depletion to accumulation in the capacitance--voltage (C--V) curve of the FP-MOS--HEMT demonstrates a high-quality interface of Al2O3/AlInN. In addition, a large off-state breakdown voltage of 133 V, a high field-plate efficiency of 170 V/um and a negligible double-pulse current collapse is achieved in the FP-MOS--HEMT. This is attributed to the adoption of an ultra-thin Al2O3 gate dielectric and also of a field-plate on the dielectric of an appropriate thickness. The results show a great potential application of the ultra-thin ALD-Al2O3 FP-MOS--HEMT to deliver high currents and power densities in high power microwave technologies. [ABSTRACT FROM AUTHOR]