A study of transition from n-to p-type based on hexagonal WO3 nanorods sensor

Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 ℃ using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3 nanorods with diameters ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range 0.5 ppm-5 ppm and at working temperatures in the range 25 ℃-250 ℃. The obtained WO3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2 gas, the WO3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 ℃, whereas, it behaves as a p-type semiconductor below 50 ℃. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 sensors based on hexagonal WO3 nanorods.     

High temperature susceptibility of semimagnetic-semiconductor Zn1-xMnxS

This paper gives an analysis of the high temperature susceptibility of diluted semimagnetic-semiconductor Zn_{1 − x}Mn_xS. The high-temperature susceptibility of Zn_{1 − x}Mn_xS was found to behave in accordance with the Curie-Weiss law. From _χ(T) measurements the exchange integral of Mn²⁺ -Mn²⁺ interaction 2J₁/k_B = (-34.6±0.5) K (effective exchange integral) was obtained. A spin S = 2.6±0.1, close to its atomic value S = , was also found. The role of the superexchange in this alloy is shortly discussed at the end of the paper.     

Deviations from the Curie-Weiss law in the magnetic susceptibility of dilute magnetic alloys

The magnetic susceptibility of dilute magnetic alloys of Mn in Rh and Fe in a Nb-Mo solid solution deviates from the Curie-Weiss law. The following temperature dependence is observed: Δ_χ = C/(T + T_K) + log (T_K/T), with ≡ 0 for T > T_K⁰.     

Rare decays of the tau lepton at Belle

We report recent results of searches for lepton flavor violation and second class current in decays of τ leptons using the data sample collected in the Belle experiment at the KEKB electron-positron asymmetricenergy collider.     

Laser-Assisted Elastic Electron Scattering from Argon

The second Born approximation （SBA） theory is applied to the study of electron-atom scattering in the presence of a CO2 laser field.The absolute differential crass sections of e-Ar scattering are calculated with multiphoton exchange in two special scattering geometries G1 （for small-angle scattering） and G2. For geometry G1, compared with the results of two different model potentials for electron elastic scattering by atoms, it is found that electronatom polarization potential plays an important role in laser-assisted electron-atom scattering. Some calculational results in geometries G2 are given. Our results are found to be better than other theoretical results as compared with the experimental data in geometries G1 and G2.     

Relativistic treatment of the spin-zero particles subject to the second Poschl-Teller-like potential

The three-dimensional Klein-Gordon equation is solved for the case of equal vector and scalar second Poschl-Teller potential by proper approximation of the centrifugal term within the framework of the asymptotic iteration method. Energy eigenvalues and the corresponding wave function are obtained analytically. Eigenvalues are computed numerically for some values of n and It is found that the results are in good agreement with the findings of other methods for short-range potential.     

Magnetic properties of Europium-graphite intercalation compound C6Eu

An ordered state with a complex magnetic structure has been observed below 4CK. The magnetization for H ⊥ c (c; the c-axis) shows a field-induced phase transition from a small magnetic moment state ( ～ 0.6μ_B) at lower fields to a larger moment one ( 2.2 - 2.5μ_B) above 25kG. The transition field depends on temperature and is found to be 5 - 2kG. The magnetization for H//c has only a sublinear field dependence. Above 40K the magnetic susceptibility obeys the Curie-Weiss law with θ = +1.3K and the molar Curie constant C_m = 6.78, which suggests that Eu ion is divalent in C₆Eu.     

Approaching the ground state of the kagomé antiferromagnet

Y0.5Ca0.5BaCo4O7 contains kagomé layers of Co ions, whose spins are strongly coupled, with a Curie-Weiss temperature of -2200 K. At low temperature, T=1.2 K, our diffuse neutron scattering study with polarization analysis reveals characteristic spin correlations close to a predicted two-dimensional coplanar ground state with staggered chirality. The absence of three-dimensional long-range antiferromagnetic order indicates negligible coupling between the kagomé layers. The scattering intensities are consistent with high spin S=3/2 states of Co2+ in the kagomé layers and low spin S=0 states for Co3+ ions on interlayer sites. Our observations agree with previous Monte Carlo simulations indicating a ground state of effectively short range, staggered chiral spin order.     

BaTi2As2O电子结构的第一性原理研究

利用基于密度泛函理论的平面波赝势方法,研究BaTi2As2O的能带结构、费米面和态密度.发现:BaTi2As2O是一种非磁性金属,费米能级处的态密度主要来自Ti原子的3d电子,Ti 3d轨道和As 4p轨道有较强的杂化.没有发现其磁性基态,说明Ti原子上没有局域磁矩,与Pickett对Na2Ti2Sb2O的研究结论相吻合.     

Spectroscopy of C

The ¹⁴C(t, p)¹⁶C reaction locates five new states in ¹⁶C, at excitation energies of 3120 ± 15, 3983 ± 10, 4136 ± 10 and 6109 ± 15 keV, in addition to the g.s. and 1.76 MeV states. The 3.02 and 3.98 MeV states appear to be the second 0⁺ and 2⁺ 2p-2h states, respectively. The 4.14 MeV state has J^π = 4⁺ and the 6.11 MeV state has J^π = 2⁺, 3⁻, or 4⁺.     

Unconventional superconductivity and electron correlations in the cobalt oxyhydrate Na0.35CoO2.yH2O from nuclear quadrupole resonance

We report a careful 59Co nuclear quadrupolar resonance measurement on the recently discovered cobalt oxyhydrate Na0.35CoO2.yH(2)O superconductor from T=40 K down to 0.2 K. We find that in the normal state the spin-lattice relaxation rate 1/T(1) follows a Curie-Weiss type temperature (T) variation, 1/T(1)T=C/(T-theta), with theta=-42 K, suggesting two-dimensional antiferromagnetic spin correlations. Below T(c)=3.9 K, 1/T(1) decreases with no coherence peak and follows a T(n) dependence with n approximately 2.2 down to approximately 2.0 K but crosses over to a 1/T(1) proportional to T variation below T=1.4 K, which suggests non-s-wave superconductivity. The data in the superconducting state are most consistent with the existence of line nodes in the gap function.     

Low-temperature phase and magnetic interactions in FCC Fe-Cr-Ni alloys

The low-temperature (5 K < T < 300 K) magnetic properties of a set of nine isostructural fcc Fe-Cr-Ni (Fe ≈ 68 at %, Cr ≈ 20 at%, Ni ≈ 9 at%) alloys were studied by SQUID magnetometry, neutron diffraction and ultrasonic techniques. Type-1 antiferromagnetic (AF) ordering was observed below the Néel temperature, T_N. The dc susceptibility, χ(T), did not exhibit a simple Curie-Weiss dependence. Above T_N, atemperature independent component χ₀ was observed, i.e., χ(T) = χ₀ + C / (itT + θ. T_N was systematically influenced by the lattice parameter, a, decreasing from (47.9 ± 0.5) K to (35.0 ± 0.5) K as a increased by only 0.25%. The average magnetic moment of ≈ 0.6μ_B obtained from neutron scattering was lower than the ≈ 1 μ_B obtained from the SQUID data. Mean field estimates of antiferromagnetic nearest-neighbors exchange interaction (J₁) and ferromagnetic second-nearest-neighbors interaction (J₂) indicate that |J₂/J₁|≈ 1.5. We believe that this is evidence of the RKKY interaction, and self-consistently argue that only the external d electrons are responsible for the localized average moment. This may mean that s-d hybridization of the external electrons is weak in these alloys.     

R型铁氧体BaFe4-xTi2+xO11的化学组态以及磁性行为的研究

本文通过传统的固相反应法制备了R型六角铁氧体BaFe_4-xTi_2+xO₁₁ (x= 0, 0.25, 0.5, 0.75, 1), 并且对它的原子价态以及磁性行为进行了研究. X 射线光电子能谱(XPS)结果显示了随着掺杂含量的增加, 体系中Fe³⁺离子逐渐减少而Fe²⁺离子逐渐增加. 由于具有非对称结构的阻挫晶格中存在各种关联作用的竞争, 使得BaFe_4-xTi_2+xO₁₁体系表现出了复杂的磁有序行为, 在T₁～250 K和T₂～83 K两处存在磁转变. 对这一系列掺杂样品, 在相变温度T₁之上表现顺磁行为, 而在相变温度T₂前后的磁化强度都表现出低场下随磁场的增加快速增加, 高场下则线性变化且在5×10⁴ Oe时还未达到饱和的行为, 表明这一系列掺杂样品是典型的倾斜反铁磁态(canted antiferromagnetic) 或者亚铁磁态.     

First-Principles Calculations of Atomic and Electronic Properties of T1 and In on Si（111）

The atomic and electronic structures of T1 and In on Si（111） surfaces are investigated using the firstprinciples total energy calculations. Total energy optimizations show that the energetically favored structure is 1/3 ML T1 adsorbed at the T4 sites on Si（111） surfaces. The adsorption energy difference of one T1 adatom between （√3 × √3） and （1 × 1） is less than that of each In adatom. The DOS indicates that TI 6p and Si 3p electrons play a very important role in the formation of the surface states. It is concluded that the bonding of TI adatoms on Si（111） surfaces is mainly polar covalent, which is weaker than that of In on Si（111）. So T1 atom is more easy to be migrated than In atom in the same external electric field and the structures of T1 on Si（111） is prone to switch between （√3 × √3） and （1 × 1）.     

Study on the pre-chopper in CSNS LEBT

Physical designing of the pre-chopper in CSNS LEBT is carried out, which includes the deflecting voltage, the length and the width of the deflecting plates, and the gap between the deflecting plates. The most outstanding feature of the design is that both the gap and the width vary with the beam envelope size. So both the requried deflecting voltage and the loaded capacitance are lowered. In order to avoid destruction of the space charge neutralization by the pre-chopper in the whole LEBT, an electron-trapping electrode is arranged to confine the electrostatic field of the pre-chopper to the local area. To examine the reliability of the pre-chopping design in CSNS LEBT, a similar pre-chopping design in ADS RFQ LEBT is set up and an experiment on the pre-chopper is prepared. 3-dimensional simulations are carried out to determine the loaded capacitance and the applied voltage of the electron-trapping electrode.     

Synchronization in a Mutualism Ecosystem Induced by Noise Correlation

Understanding the cause of the synchronization of population evolution is an important issue for ecological improvement. Here we present a Lotka-Volterra-type model driven by two correlated environmental noises and show, via theoretical analysis and direct simulation, that noise correlation can induce a synchronization of the mutualists. The time series of mutual species exhibit a chaotic-like fluctuation, which is independent of the noise correlation, however, the chaotic fluctuation of mutual species ratio decreases with the noise correlation. A quantitative parameter defined for characterizing chaotic fluctuation provides a good approach to measure when the complete synchronization happens.     

Metric of States

Metric of quantum states plays an important role in quantum information theory. In this letter, we find the deep connection between quantum logic theory and quantum information theory. Using the method of quantum logic, we can get a famous inequality in quantum information theory, and we answer a question raised by S. Gudder.     

Remarks on interpretations of the Eotvos experiment and misinterpretation of E=mc^2

The Eotvos experiment on the verification of equivalence between inertial mass and gravitational mass of a body is famous for its accuracy. A question is, however, can these experimental results be applied to the case of a physical space in general relativity, where the space coordinates could be arbitrary？ It is pointed out that it can be validly applied because it has been proven that Einstein＇s equivalence principle for a physical space must have a frame of reference with the Euclidean-like structure. Will claimed further that such an overall accuracy can be translated into an accuracy of the equivalence between inertial mass and each type of energy. It is shown that, according to general relativity, such a claim is incorrect. The root of this problem is due to an inadequate understanding of special relativity that produced the famous equation E=mc^2, which must be understood in terms of energy conservation. Concurrently, it is pointed out that this error is a problem in Will＇s book, ‘Theory and Experiment in Gravitational Physics＇.     

Design and construction progress of BRIF

A new RIB project, the Beijing Radioactive Ion-beam Facility （BRIF）, has been running at CIAE since 2004. In this project, a 100 MeV H-cyclotron, CYCIAE-100, is selected as the driving accelerator providing a 75-100 MeV, 200-500 μA proton beam. An ISOL system employs two stage separators to reach the mass resolution of 20000. Its RIB beam will be injected into the existing Tandem and a superconducting booster installed down stream of the Tandem will increase the energy by 2 MeV/q. The progress of BRIF, giving special emphasis to CYCIAE-100, will be introduced in this paper.     

D^0D^0 mixing and other recent charm results from BABAR

Studies in which BABAR data have shown evidence for mixing in the neutral charm meson system are presented. A new measurement of the lifetime difference parameter ycp = （1.16±0.22±0.18）% is described. Results are also presented from a systematic study of DK and D＊K invariant mass distributions from a 470 fb^-1 sample of asymmetric e^＋e^- interactions recorded by the BABAR detector at the PEP-Ⅱ storage rings. A new charmed-strange meson has been observed with mass [3044 ± 8stat （-5^＋30 ）syst] MeV/c^2 and width [239± 35stat （-42^＋46）syst]MeV/c^2.