Effects of Nd2O3 and TiO2 Addition on the Microstructures and Microwave Dielectric Properties of BaO-Nd2O3-TiO2 System

The effects of Nd₂O₃ and TiO₂ addition on the microstructures and microwave dielectic properties of BaO-Nd₂O₃-TiO₂ system were investigated. BaNd₂Ti₄O₁₂ or BaNd₂Ti₅O₁₄ phases were observed for compositions based on BaO/Nd₂O₃ = 1 ratio. The compositions deviated from BaO/Nd₂O₃ = 1 ratio were composed of major phases of BaNd₂Ti₄O₁₂ or BaNd₂Ti₅O₁₄, and the compound of Nd₂O₃ and TiO₂ (Nd₂Ti₂O₇) or that of BaO and TiO₂ (BaTi₄O₉). The microstructure of ceramic with BaO·Nd₂O₃ ·4TiO₂ composition varied from spherical grains to needlelike grains with increasing sintering temperature. With increasing Nd₂O₃, the optimum sintering temperature with maximum density increased, and the dielectric constant( · _r) and quality factor(Q) decreased due to the formation of secondary phases. With increasing TiO_2/ the optimum sintering temperature and the dielectric constant decreased with increased Q value. And the temperature coefficient of resonant frequency, ·_f shifted toward positive direction. The dielectric ceramics with BaO/Nd₂O₃ = 1 showed Q values of above 2000 and dielectric constants of above 80 at 3GHz.     

Microstructural study of the effect of an excess of Y2BaCuO5 and BaSnO3 doping on the texturing process of YBa2Cu3O7−x bulk superconductors

Melt texture process of YBCO leads to a YBa₂Cu₃O_7−x matrix where Y₂BaCuO₅ particles are observed. The Y₂BaCuO₅ inclusions size and distribution depend upon several parameters: YBa₂Cu₃O_7-x grain size in the presintered, heating rate, dopants. The influence of an excess of Y₂BaCuO₅ and/or BaSnO₃ on these Y₂BaCuO₅ particles are observed in the liquid phase and in the texture domain. According to the dopant used, two kinds of coarsening of Y₂BaCuO₅ can be observed: an isotropic and an anisotropic. The control of the distribution of Y₂BaCuO₅ particle size is of primary interest to improve the efficiency of the MTG process. In particular large cooling rate (5°C/h) during the texture formation could be used by adding Y₂BaCuO₅ + BaSnO₃ to YBa₂Cu₃O_7−x composition.     

Electronic Structure and Thermoelectric Properties of Si-Based Clathrate Compounds

Thermoelectric properties of Au-substituted Si-based clathrates, Ba₈AuGa₁₃Si₃₂ and Ba₆A₂AuGa _x Si_45−x (A = Sr, Eu, x = 13, 14), were experimentally and theoretically investigated. The polycrystalline samples of the Au-substituted Si-based clathrates were prepared by using the spark plasma sintering technique. The electronic structure of Ba₆A₂AuGa₁₃Si₃₂ was theoretically calculated by ab initio calculations, and the thermoelectric properties of Ba₆A₂AuGa _x Si_45−x were estimated through the calculated electronic structure. The effective mass of Ba₆A₂AuGa _x Si_45−x was experimentally estimated to be greater than that of Ba₈AuGa₁₃Si₃₂. Experimentally observed electronic properties agree with the calculations for Ba₆A₂AuGa _x Si_45−x . The maximum ZT value of Ba₆Sr₂AuGa₁₄Ge₃₁ is about 0.5 at 850 K. The calculated thermoelectric properties agree very well with the experimental results in the range from room temperature to 900 K.     

The Effect of Cu Addition on the System Stability and Thermoelectric Properties of Bi2Te3

Cu-doped Bi₂Te₃ nanopowders with nominal composition Cu _x Bi₂Te₃ (x = 0, 0.01, 0.025, and 0.05) were synthesized by a gas-induced-reduction method using TeO₂, Bi(NO₃)₃·5H₂O and Cu(NO₃)₂·3H₂O as raw materials and then hot-pressed into bulk materials. x-Ray diffraction (XRD) analysis indicates that, when x ≠ 0, pure Cu _x Bi₂Te₃ phase was obtained, and that when x = 0, Bi₂Te₃ mixed with a small amount of Bi₂TeO₅ was obtained. Field emission scanning electron microscopy observation reveals that Cu addition significantly reduces the grain sizes of the materials. First-principle calculations show that the order of the free energies of the materials is: Cu-doped Bi₂Te₃ (substitution of Cu for Bi) < Cu intercalated Bi₂Te₃ < Bi₂Te₃. The electrical and thermal conductivities decrease and the Seebeck coefficient increases with Cu addition. The maximum figure of merit, ZT, reaches 0.67 at 500 K for a Cu_0.05Bi₂Te₃ sample.     

Far-Infrared Laser Stark Spectroscopy of CH3OD

The high resolution Stark spectra of the singly deuterated methanol isotope, CH₃OD, have been studied using the HCN laser with Stark fields up to approximately 60 000 V/cm. Numerous families of absorption lines have been observed in both parallel and perpendicular polarizations, resulting in the following assignments: with the 311 μm line – J _K = 18₁ ← 18₀ E ₂, υ _t = 1; and with the 337 μm line – J _k = 6₄ ← 5₃ E ₂, υ _t = 0 and J _K = 14₆ ← 13₅ A, υ _t = 1. Zero-field frequencies for the assigned transitions are in agreement with Fourier transform measurements and those calculated from the available molecular constants.     

Multiphoton ionization of acetone-water clusters at 355 nm

Ti me of flight mass spectrometer(TOF-MS) is verysuccessful apparatus to detect clusterions[1-3].It isknown protonatedions are easy to formedin multipho-tonionization( MPI)[4 ,5].Acetoneis the si mplest molecule in the ketones ,it isvery popularinvestigat…     

Thermoelectric properties of Ce x Nd y Co4Sb12 skutterudites

Experimental results of studying the thermoelectric properties of Co₄Sb₁₂, Ce_0.1Nd_0.5Co₄Sb₁₂, and Ce_0.5Nd_0.1Co₄Sb₁₂ prepared by induction melting are presented. The thermoelectric figure of merit ZT of the studied Co₄Sb₁₂ is approximately two times higher than ZT of unfilled skutterudites prepared by the conventional solid-phase synthesis method. The figure of merit of Ce_0.1Nd_0.5Co₄Sb₁₂ and Ce_0.5Nd_0.1Co₄Sb₁₂ appears lower than ZT of Co₄Sb₁₂ due to the presence of an impurity phase of metal antimony in the first two samples. It is assumed that the thermoelectric properties of filled skutterudites can be significantly improved by optimizing the induction melting method.

     

Analysis of the detectivity for triple-layer heterojunction GaSb/GaInAsSb infrared detectors

In this paper, the detectivity is calculated and analyzed with the front-or backside illuminated case for both N-GaSb/p₂-Ga_0.8In_0.2As_0.19Sb_0.81/p₁-Ga_0.9In_0.1As_0.09Sb_0.91 and N₁-GaSb/n₂-Ga_0.9In_0.1As_0.09Sb_0.91/p-Ga_0.8In_0.2As_0.19Sb_0.81 infrared photovoltaic detectors, respectively. The analysis results show that the main absorption appears in the p-type Ga_0.8In_0.2As_0.19Sb_0.81 material with either front- or backside illuminated case for above two structures. In each structure, the carrier concentration obviously affects the detectivity. The carrier concentration in the wide-bandgap material for the isotype heterojunction should be reduced as low as possible to reduce the tunneling rate at the isotype heterointerface. Moreover, the change of the detectivity with the p-side surface recombination velocity for the N₁-n₂-p structure is more sensitive than that with the p₁-side surface recombination velocity for the N-p₂-p₁ structure. In the N-p₂-p₁ structure with the incident light from the p₁-side surface, two-color detection is achieved.     

Decomposition studies of triisopropylantimony and triallylantimony

The pyrolysis of triisopropylantimony ((C₃H₇)₃Sb) and triallylantimony ((C₃H₅)₃Sb) has been investigated mass-spectrometrically in He and D₂ using a SiO₂ flow tube reactor at atmospheric pressure. Both temperature and time dependencies of percent decomposition were studied and the reaction products were analyzed. The overall decomposition processes for both compounds were found to be homogeneous and first order. (C₃H₇)₃Sb pyrolyzes at 250-350° C with no effect of the ambient gas. However, C₃H₆, C₃H₈, and C₆H₁₄ (2,3-dimethylbutane) were produced in He whereas C₃H₃D appeared in D₂. The pyrolysis is believed to begin via bond cleavage to generate the free C₃H₇ radicals that, in turn, recombine and disproportionate. Isopropyl radicals react slowly with D₂, producing the C₃H₇D detected. For (C₃H₅)₃Sb, the pyrolysis takes place at 100-160° C. The only major product is C₆H₁₀ (1,5-hexadiene). Both the pyrolysis rate and products were independent of the ambient. Two possible mechanisms, homolysis and reductive coupling, are discussed. Assuming that homolysis is the rate-limiting step for the pyrolysis of both (C₃H₇)₃Sb and (C₃H₅)₃Sb, bond strengths of 30.8 and 21.6 kcal/mole for C₃H₇—Sb and C₃H₆—Sb were determined from the experimental data. When either (C₃H₇)₃Sb or (C₃H₅)₃Sb was mixed with trimethylindium, a nonvolatile, liquid material, probably an adduct, was formed.     

Growth of Ge1 − x Sn x solid solution films and study of their structural properties and some of their photoelectric properties

From the charge state and closeness of the covalent radii of molecules of the solution-forming components, the possibility of the formation of the solutions Si_{1 ? x} Ge _x , Si_{1 ? x} Sn _x , (Si₂)_{1 ? x} (SnC) _x , Ge_{1 ? x} Sn _x , (Ge₂)_{1 ? x} (SiSn) _x , (SiC)_{1 ? x} (GeC) _x , (GeC)_{1 ? x} (SnC) _x , and (SiGe)_{1 ? x} (SnC) _x based on chemical elements of Group IV has been predicted. Single-crystal films of the substitutional solid solution Ge_{1 ? x} Sn _x (0 ≤ x ≤ 0.03) have been grown on Ge substrates by liquid-phase epitaxy. X-ray diffraction patterns, spectral photosensitivity, and the I–V characteristics of the obtained n-Ge-p-Ge_{1 ? x} Sn _x heterostructures have been investigated. The lattice parameters of the epitaxial film and the substrate a _f = 5.6812 Å and a _s = 5.6561 Å have been determined. The spectral photosensitivity of the n-Ge-p-Ge_{1 ? x} Sn _x heterostructures encompasses the photon energy range from 0.4 to 1.4 eV. It is shown that the forward portion of the I–V characteristics of the investigated structures at low voltages (up to 0.5 V) is described by the exponential dependence I = I ₀exp(qV/ckT) and at high voltages (V > 0.5 V), by the power dependence I ∝ V ^α with the values α = 2 at V = (0.5–0.9) V, α = 1.3 at V = (0.9–1.4) V, and α = 2 at V > 1.4 V. The experimental data are explained within the double injection model for the n-p-p structure using the drift mechanism of current transport in the ohmic relaxation mode taking into account the inertia of the electron exchange inside a recombination complex.     

Kinetic Studies of the Interfacial Reaction of the Ba2YCu3O6+x Superconductor with a CeO2 Buffer

Interfacial reactions between the Ba₂YCu₃O_6+x superconductor and the CeO₂ buffer layers employed in coated conductors have been modeled experimentally by investigating the kinetics of the reaction between Ba₂YCu₃O_6+x films and CeO₂ substrates. At 810°C, the Ba₂YCu₃O_6+x -CeO₂ join within the BaO-Y₂O₃-CeO₂-CuO _x quaternary system is nonbinary, thereby establishing the phase diagram topology that governs the Ba₂YCu₃O_6+x /CeO₂ reaction. At a mole ratio of Ba₂YCu₃O_6+x :CeO₂ of 40:60, a phase boundary was found to separate two four-phase regions. On the Ba₂YCu₃O_6+x -rich side of the join, the four-phase region consists of Ba₂YCu₃O_{6 +x} , Ba(Ce_1−z Y _z )O_3−x , BaY₂CuO₅, and CuO _x ; on the CeO₂ rich side, the four phases were determined to be Ba(Ce_1−z Y _z ) O_3−x , BaY₂CuO₅, CuO _x and CeO₂. The Ba₂YCu₃O_6+x /CeO₂ reaction is limited by solid-state diffusion, and the reaction kinetics obey the parabolic rule, x = Kt ^1/2, where x = thickness of the reaction layer, t = time, and K = a constant related to the rate constant; K was determined to be 1.6 × 10⁻³ μm/s^1/2 at 790°C and 4.7 × 10⁻³ μm/s^1/2 at 830°C. The activation energy for the reaction was determined to be E _act = 2.67 × 10⁵ J/mol using the Arrhenius equation.     

VOLTE容灾机制研究及优化方案

_{本文首先对VOLTE现网网络结构及容灾机制进行研究分析,发现现存容灾机制中存在的缺点和不确定性,针对其中的问题,针对性地进行了深入研究和分析,创新的提出了1种快速容灾抢通方案,以达到提升VOLTE业务运维能力和用户业务感知的目的。}     

Effects of Ge Dopant on Thermoelectric Properties of Barium and Indium Double-Filled p-Type Skutterudites

A series of Ge-doped and (Ba,In) double-filled p-type skutterudite materials with nominal composition Ba_0.3In_0.2FeCo₃Sb_12?x Ge _x (x = 0 to 0.4, Δx = 0.1) have been prepared by melting, quenching, annealing, and spark plasma sintering methods. The effects of Ge dopant on the phase composition, microstructure, and thermoelectric properties of these materials were investigated in this work. A single-phase skutterudite material was obtained in the samples with 0 < x ≤ 0.2, and trace Fe₃Ge₂ was detected in the samples with x ≥ 0.3. The electrical conductivity increased and Seebeck coefficient decreased with increasing x in the range of 0 to 0.2, while the inverse behaviors of electrical conductivity and Seebeck coefficient were observed in the samples with x ≥ 0.3. The variations of electrical conductivity and Seebeck coefficient are attributed to the significant increase in the carrier concentration in the x range of 0 to 0.2 and the intensive impact of Fe₃Ge₂ when x ≥ 0.3. The lattice thermal conductivity of all the Ge-doped samples was considerably reduced as compared with the undoped Ba_0.3In_0.2FeCo₃Sb₁₂ sample, and the lowest value of lattice thermal conductivity of the Ba_0.3In_0.2FeCo₃Sb_11.8Ge_0.2 sample reached 1.0 W m^?1 K^?1 at 700 K. The highest ZT value of 0.54 was obtained at 800 K for the Ba_0.3In_0.2FeCo₃Sb_11.7Ge_0.3 sample, increased by 10% as compared with that of Ba_0.3In_0.2FeCo₃Sb₁₂.     

Determination of the composition of multicomponent chalcogenide semiconductors by X-ray fluorescence analysis

The composition of As _x (Ge _y Se_{1 ? y} )_{1 ? x} glassy alloys is quantitatively determined by measuring the X-ray fluorescence spectrum of a Ge_0.2As_0.4Se_0.4 reference alloy. The atomic fractions of arsenic, germanium, and selenium are calculated from the X-ray fluorescence spectra and the x _RFA = f(x) and y _RFA = f(y) dependences are plotted. These dependences make it possible to determine the composition of the glasses with an accuracy of ±0.0005 for x and y. This procedure is effective for finding the concentration of the tin impurity in Pb_{1 ? x} Sn _x Se crystalline solid solutions. However, it is impossible to determine the content of tellurium in Te _x (As _y Se_{1 ? y} )_{1 ? x} glassy alloys because the alloy components have significantly different X-ray fluorescence characteristics.     

Data retention characteristics of MANOS-type flash memory device with different metal gates at various levels of charge injection

We investigated the impact of charge injection and metal gates (Al and Pt) on the data retention characteristics of metal–alumina–nitride–oxide–silicon (MANOS) devices for NAND flash memory application. Through the theoretical and experimental results, the highly injected charge (ΔV_TH) could cause the band bending of Al₂O₃, which reduced the tunneling distance across Al₂O₃. Thus, the dominant charge loss path is not only toward SiO₂ but also toward Al₂O₃ direction. Compared to low-metal work function (Ф_M), ONA stack with high-Ф_M showed better data retention characteristics, even if ΔV_TH is high. This could be explained by Fermi level alignment for different Ф_M, which results in the reduction of electric field across the Al₂O₃ compensated by the ΔФ_M (Ф_Pt ? Ф_Al).     

Structure of Na Species in Promoted CaO-Based Sorbents and Their Effect on the Rate and Extent of the CO2 Uptake

To advance CaO-based CO₂ sorbents it is crucial to understand how their structural parameters control the cyclic CO₂ uptake. Here, CaO-based sorbents with varying ratios of Na₂CO₃:CaCO₃ are synthesized via mechanochemical activation of a mixture of Na₂CO₃ and CaCO₃ to investigate the effect of sodium species on the structure, morphology, carbonation rate and cyclic CO₂ uptake of the CO₂ sorbents. The addition of Na₂CO₃ in the range of 0.1–0.2 mol% improves the CO₂ uptake by up to 80% after 10 cycles when compared to ball-milled bare CaCO₃, while for Na₂CO₃ loadings >0.3 mol% the cyclic CO₂ uptake decreases by more than 40%. Energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy, X-ray absorption spectroscopy (XAS), and ²³Na MAS NMR, reveal that in sorbents with Na₂CO₃ contents <0.3 mol% Na exists in highly distributed, noncrystalline [Na₂Ca(CO₃)₂] units. These species stabilize the surface area of the sorbent in pores of diameters >100 nm, and enhance the diffusion of CO₂ through CaCO₃. For Na₂CO₃ contents >0.3 mol%, the accelerated deactivation of the sorbents via sintering is related to the formation of crystalline Na₂Ca(CO₃)₂ and the high mobility of Na.     

Effects of Process Variable Control on the Thermoelectric Properties of the Zn0.98Ga(Al)0.02O System

The main factors influencing the different solubility limits of Al- and Ga-doped ZnO systems are studied. The different thermoelectric properties of Al- and Ga-doped ZnO systems were attributed in prior studies to the different solubility limits and secondary phases of these systems. In this study, the origin of these differences, i.e., the Ga₂O₃(ZnO)₉ secondary phase, was suppressed by a low-temperature synthesis process for the Zn_0.98Ga_0.02O solid solution. As a result, a novel synthesis process for Zn_0.98Ga_0.02O solid solution without the Ga₂O₃(ZnO)₉ phase was established, and the thermoelectric properties with and without the Ga₂O₃(ZnO)₉ secondary phase were compared. The thermoelectric properties of Zn_0.98Al_0.02O and Zn_0.98Ga_0.02O specimens without Al₂O₃(ZnO)₉/Ga₂O₃(ZnO)₉ phases were also compared.     

Pyrolysis of tertiarybutylphosphine

The reaction mechanism for the pyrolysis of tertiarybutylphosphine (TBP) has been studied in an atmospheric pressure flow tube reactor using a time-of-flight mass spectrometer to analyze the gaseous products. D₂ was used as the carrier gas in order to label the reaction products. The temperature and time dependence of TBP pyrolysis were investigated above a silica surface, which was found to have no effect on TBP decomposition. However, the pyrolysis rate and products are strongly dependent on the input TBP concentration, suggesting the TBP pyrolysis involves second order reactions. A simple free radical mechanism model is proposed which includes 4 major reactions: C₄H₉PH₂ = C₄H₉ + PH₂ C₄H₉ + C₄H₉PH₂ = C₄H₁₀ + C₄H₁₀ + C₄H₉PH C₄H₉PH = C₄H₉ + PH C₄H₉ = C₄H₈ + H. Arrhenius parameters for these reactions are reported.     

On the extraction of the source and drain series resistances of MOSFETs

This article reviews and scrutinizes various proposed methods to extract the individual values of drain and source resistances (R_D and R_S) of MOSFETs, which are important device parameters for modeling and circuit simulation. In general, these methods contain three basic steps: (1) the extraction of the total drain and source resistance (R_D+R_S); (2) the extraction of the difference between the drain and the source resistances (R_D−R_S); and (3) the calculation of R_D and R_S from the knowledge of (R_D+R_S) and (R_D−R_S). These methods are tested and compared in the environments of circuit simulator, device simulation and measurements.     

Synergistic Effects of Phase Transition and Electron-Spin Regulation on the Electrocatalysis Performance of Ternary Nitride

Transition metal nitrides (TMNs) have great potential use in energy storage and conversion owing to tunable electronic and bonding characteristics. Novel iron rich nitrides nanoparticles anchored on the N-doped porous carbon, named as (Co_xFe_1–x)₃N@NPC (0 ≤ x < 0.5) are designed here. The synergistic effects of phase transition and electron-spin regulation on oxygen electrocatalysis are testified. A core–shell structure of (Co_xFe_1–x)₃N with high dispersibility is induced by an intermediate phase transition process, which significantly suppresses coarsening of the metallic nitrides. The Co incorporation regulates d-band electrons spin polarization. The t_2g⁵e_g¹ of Fe^II with the ideal e_g electron filling boosts intrinsic activity. (Co_0.17Fe_0.83)₃N@NPC with optimal cobalt content holds electronic configuration with moderate e_g electron filling (t_2g⁵e_g¹), which balances the adsorption of *O₂ and the hydrogenation of *OH, improving bifunctional catalytic performances. Both liquid and solid-state zinc–air batteries assembled based (Co_0.17Fe_0.83)₃N@NPC cathodes substantially deliver higher peak power density and remarkable energy density.