bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of oxygen partial pressure on the crystal quality and optical properties of Mg-doped ZnO films
Authors: Bao Shan-Yong  , Dong Wu-Jun  , Xu Xing  , Luan Tian-Bao  , Li Jie  , Zhang Qing-Yu  ,   Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Opto-electronic Technology, Dalian University of Technology, Dalian 116024, China
Published: December 2020

Zn1-xMgxO films have been deposited on Al2O3(0001) substrates at different oxygen pressures by using pulsed laser deposition method. The influence of oxygen pressure on the crystal quality and optical properties of the films is studied with X-ray diffraction (XRD), transmittance spectra, and photoluminescence (PL). It is found that the crystal quality of the films lowers with increasing of oxygen pressure from 10-4Pa to 10 Pa. At the pressure of 10-4 Pa, the epitaxial relationship between the film and sapphire substrate is determined to be ZnMgO (0001)// Al2O3(0001),ZnMgO 1010]//Al2O3 1120]. In the oxygen rich environment, however, another epitaxial relationship, ZnMgO (0001)//Al2O3(0001) and ZnMgO 1010]//Al2O3 1010], is also present in the films, which is suggested to be responsible for the decline of the crystal quality. Compared with pure ZnO films, the UV peak of Zn1-xMgxO alloys shows red-shift from 3.374 to 3.332 eV with increasing oxygen working pressure increasing from 10-4 Pa up to 10 Pa. The difference in red-shifts can be attributed to the decrease of Mg content in the films resulting from the variation of oxygen pressure. A broad UV PL spectrum was observed at 10 K in the films deposited under different pressures and can be decomposed into two recombination processes of excitons, corresponding to the bound and the localized exciton luminescence, respectively. The binding energy of bound excitons in the ZnMgO films is larger than that in pure ZnO and has an increasing trend with increasing oxygen pressure.
Monoclinic phase of erbium oxide coatings fabricated by pulsed magnetron sputtering
Authors: Li Xin-Lian  , Wu Ping  , Qiu Hong  , Chen Sen  , Song Bin-Bin  ,   Department of Physics, School of Applied Science, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

Erbium oxide coatings were fabricated by midfrequency pulsed reactive magnetron sputtering by varying the deposition conditions with respect to the sputtering power from 78 W to 124 W and substrate temperature from room temperature to 677 ℃. Atomic force microscopy, nanoindentation, X-ray diffraction and grazing incidence X-ray diffraction were used to investigate the coatings’ surface morphology, mechanical properties and crystallization behaviors. Electrical properties of the coatings were also measured. Erbium oxide coatings fabricated by pulsed magnetron sputtering have high deposition rate, varying from 28 nm/min to 68nm/min. A monoclinic Er2O3 phase is obtained in the coatings. The crystalline quality of the coatings decreases with the increasing of the sputtering power. The diffraction intensity of monoclinic phase decreases as the substrate temperature was increased from room temperature to 500 ℃ and 677 ℃. It is believed that the high deposition rate and low substrate temperature could lead to the formation of the monoclinic Er2O3 coatings. The hardness and elastic modulus of the coatings deposited at substrate temperatures from room temperature to 677 ℃ vary from 11.9 GPa to 15.7 GPa and from 179 GPa to 225 GPa, respectively. The coatings deposited from room temperature to 677℃ all have high resistivity, varying from 1.5×1012 Ω ·cm to 3.1×1012 Ω ·cm, meeting the requirements of the insulating coatings in application to fusion reactor.
Ballistic phonon transport and thermal conductance in multi-channel quantum structure at low temperatures
Authors: Ye Fu-Qiu  , Li Ke-Min  , Peng Xiao-Fang  ,   College of Physics and Microelctronics Science, Hunan University, Changsha 410082, China
Published: December 2020

By using the elastic approximation model and scattering matrix method, we investigated the acoustic phonons transport and thermal conductance in a H-branch four-channel nanostructure. The calculated results show that, for the incident acoustic phonons of low frequency, as long as the transverse width of each channel is equal, the transmission coefficient of mode 0 in each channel almost equals 0.25 and receives no influence from the changes of the other structure parameters. But for the incident acoustic phonons of high frequency, the transmission coefficient of mode 0 in each channel is very sensitive to the structure parameters and there is bigger difference corresponding to the transmission coefficients of different channels. When the temperature is very low, the thermal conductance in each channel is about 1 4 π2k2BT/(3h). With the increase of temperature, the thermal conductance of each channel changes to different degrees. By changing the length of scattering region or the transverse width of each channel, we can control the separating degree of modes and the thermal conductance of each channel efficiently and realize acoustic phonon selective transport and thermal conduction.
First-principles study on the electronic structures and structural stability of Cd-doped ZnO
Authors: Tang Xin  , Zhang Qing-Yu  , Lü Hai-Feng  , Pu Chun-Ying  ,   (1)College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China; (2)Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Opto-electronic Technology, Dalian University of Technology, Dalian 116024, China; (3)Super Computing Center, Computer Network Information Center, Chinese Academic of Sciences, Beijing 100080, China
Published: December 2020

The VASP (Vienna Ab-initio Simulation Package) based on the density-functional theory (DFT) method combined with projector augmented wave (PAW) method is used to calculate the lattice parameters, band gap, density of states (DOS), and formation enthalpy of ZnCdO alloy by considering all the doping configurations. The calculation results indicate that the average parameters of wurtzite (wz) Zn1-xCdxO alloy, a and c, increase linearly, but the ratio of c/a does not change obviously with the increase of Cd content. With increasing Cd content, the band gap is reduced and the variation of band gap can be fitted by Eg(x)=3.28-5.04x+4.60x2, which is consistent with the experimental results. At a given Cd content, different doping configurations result in different Eg values, being one of the reasons of widening of the photoluminescence spectra of ZnCdO alloy. The DOS of wz-ZnCdO alloy in conduction band is shifted towards the lower energy side after Cd doping, causing the reduction of band gap. The reduction of band gap can be attributed to the contribution of 5s states of Cd. By comparing the formation enthalpy of wz-ZnCdO with those of zinc blende and rocksalt ZnCdO alloys, we find that the wurtzite phase of ZnCdO can coexist with zinc blende phase in the range of Cd content from 0.25 to 0.75 and will transit to the rocksalt phase at the Cd content of about 0.80.
First-principles calculation of electronic structure of (Zn,Al)O and analysis of its conductivity
Authors: Liu Jian-Jun  ,   Department of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, China
Published: December 2020

The electronic structures of ZnO and (Zn,Al)O are investigated by using the first-principles pseudopotential plane wave method in the generalized gradient approximation. The effects of Al doping on the bonding of ZnO and the interaction between electrons are analyzed from atomic population, bond population, energy band and electronic density of states based on the molecular orbital theory. Carrier concentration of (Zn,Al)O is calculated from the first-principles calculations, furthermore the change in ZnO conductivity is analyzed. The carrier concentration and the conductivity of ZnO are increased significantly by Al doped ZnO compared with the experimental results.
First-principles calculation and experimental study of Si-doped β-Ga2O3
Authors: Zhang Yi-Jun  , Yan Jin-Liang  , Zhao Gang  , Xie Wan-Feng  ,   School of Physics, Ludong University, Yantai 264025, China
Published: December 2020

By using the first-principles ultra-soft pseudo-potential (USP) approach of the plane-wave based upon density functional theory (DFT), the energy band structure, electron density of states, difference in charge density and optical properties of the intrinsic β-Ga2O3 and Si-doped β-Ga2O3 were calculated under generalized gradient approximation (GGA). The intrinsic β-Ga2O3 and Si-doped β-Ga2O3 films were deposited on sapphire (0001) substrates by pulsed laser deposition (PLD), the optical absorption spectra and reflectance spectra were measured. The results showed that the whole energy band moved to the low energy side, the conductivity was n-type, the optical band gap increased, the absorption edge shifted to short wavelength, and the reflectivity decreased. The calculation results are consistent with experimental data.
First-principles study on the electronic structures of diadochic compounds Bi2Te3- x Sex(x ≤3)
Authors: Liu Feng-Li  , Jiang Gang  , Bai Li-Na  , Kong Fan-Jie  ,   (1)College of Physical Science and Technology, Heilongjiang University, Harbin 150080, China; (2)Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

Based on density functional theory with spin-orbit corrections included, the electronic structures of diadochic compounds Bi2Te3-xSex(x≤3) have been calculated by first-principles full-potential linearized augmented plane-wave method. The calculated results indicate that spin-orbit interaction is crucial in understanding the gap structure near the Fermi energy. Bi2Te3-xSex(x≤3) are indirect-gap semiconductors, and there is a saddle point at the Γ point. The density of states near Fermi level mainly consists of p orbitals of each atom. For the chemical bonding of the various layers of atoms, the covalence bond component of X(1)—Bi is stronger than that of X(2)—Bi (X=Te, Se). With the increase of the Se mol ratio in the systems, the unit cell volume is reduced, the energy of the system is increased, and the covalence bond component of Te(1)—Bi, Se(2)—Bi, Se(1)—Bi is gradually enhanced.
Influence of NPB:CBP modulated hole transporting layer on yellow organic light-emitting device characteristics
Authors: Chen Su-Jie  , Yu Jun-Sheng  , Wen Wen  , Jiang Ya-Dong  ,   State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic science and Technology of China (UESTC), Chengdu 610054, China
Published: December 2020

Organic light-emitting devices (OLEDs) with the structure of indium-tin oxide (ITO)/N, N'-diphenyl-N, N'-bis(1-naphthyl-pheny1)-1, 1'-biphenyl-4, 4'-diamine (NPB):4, 4'-N, N'-dicarbazole-biphenyl (CBP)/CBP:bis iridium (acetylacetonate) /2, 9-dimethyl-4, 7-diphenyl-phenanthroline (BCP)/Mg:Ag were fabricated. A doping system consisting of NPB and CBP was employed as the modulated hole transporting layer. The electroluminescent characteristics of the OLEDs were investigated by adjusting the concentration proportions of NPB:CBP doping system. The results showed that the hole transporting capability can be adjusted and the power efficiency was remarkably affected by different doping concentration of NPB:CBP system. Optimized yellow light OLED with a maximum power efficiency of 18.1 lm/W was obtained with an optimum concentration proportion of NPB:CBP of approximately 1 ∶3. The improved OLED performance was attributed to the reduction of hole injection and low transporting capability by doping bipolar host material CBP in hole transporting layer, which significantly enhanced charge carrier balance and electron-hole recombination probability.
Scanning tunnelling microscope investigation of the TiSi2 nano-islands on Sr/Si(100) surface
Authors: Yang Jing-Jing  , Du Wen-Han  ,   (1)Changzhou Institute of Technology, Changzhou 213002, China; (2)National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230027, China
Published: December 2020

For the investigation of the interface stability of SrTiO3/Sr/Si(100) system during high temperature annealing process, we have grown 1—2 atom layer SrTiO3 ultra-thin film on Sr/Si(100)-2×1 substrate using pulsed laser deposition technique. After annealing, we found that nano-scale islands appear in the surface. These nano-islands show metallic property by scanning tunneling microscopy, and the STM image shows bias voltage dependence of these nano-islands. Oxygen in the oxide reacts with silicon and forms volatile silicon monoxide during vacuum annealing, while Ti atoms in the oxide react with silicon, forming C-54 TiSi2 islands.
Regulating effect of a bonding bridge on rectifying performance in molecular rectifiers
Authors: Pan Jin-Bo  , Zhang Zhen-Hua  , Qiu Ming  , Guo Chao  ,   School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410004, China
Published: December 2020

Using the density-functional theory and the non-equilibrium Greens function method, we investigated the electronic transport properties and rectifying performance of three different molecular devices based on different molecular configurations of the same molecule species. The results show that rotation of a mid-benzene ring (bonding bridge—πbridge) can change the delocalization of a molecular orbital and thus change their transport property and rectifying performance. This finding suggests that the variation of the bonding bridge orientation can control the rectifying performance of a molecular device effectively. It is of significance for designing a novel molecular rectifier.
Non-classical state effect on the persistent current in one-dimensional mesoscopic ring with electron-phonon interaction
Authors: Liang Guo-Dong  , Luo Zhi-Hua  ,   (1)Department of Optoelectronic Engineering, Jinan University, Guangzhou 510632, China; (2)Department of Physics, Guangdong University of Education, Guangzhou 510303, China
Published: December 2020

Based on the efficacy of the phonon coherent state and with consideration of the non-classical effect of the squeezed state of phonon, the influence of the electron-magnon interaction and the electron-phonon interaction on the persistent current in one-dimensional mesoscopic ring is studied. Compared with the free ring, our study shows that in one-dimensional mesoscopic ring, the amplitude of the persistent current exponentially diminishes due to the electron-magnon interaction. For the normal state electron, the interaction of the electron-phonon causes the persistent current to weakendce to the Debye-Waller effect. However, taking the correlation between the hopping electron states and the one-phonon coherent states into the equation, the ground energy of the mesoscopic system is declined in a large scale. In result, the persistent current In is increased substantially. On the other hand, taking the behavior of the two-phonon coherent state into account, as the effect of the squeezed states of phonons maintains the phase coherence of electrons, so the Debye-Waller attenuation is weakened effectively. Especially, when the squeezed angle is larger, because of the non-adiabatic correlation between the squeezed-phonon states and the coherent states of phonon, it causes a significant decline in the ground state energy and a significant increase in the squeezed angle, thus persistent current has a even more significant increase. It should be pointed out, that the persistent current shows period oscillation as the external magnetic flux changes. Even the external magnetic flux Φem=0, still the persistent current of the intrinsic has I ~ n≠0. The system continuoues to support the equilibrium spin and charge flow, the external magnetic flux only plays the role of an adiabatic parameter.
Theoretical research on two gaps in cuprate superconductors:an electronic Raman scattering study
Authors: Lu Hong-Yan  , Chen San  , Liu Bao-Tong  ,   School of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000,China
Published: December 2020

Electronic Raman experiments have shown the presence of two types of gaps in hole-doped cuprate superconductors: one is the gap that increases with underdoping and survives in the pseudogap normal state and the other is the gap that traces the superconducting dome and disappears above the transition temperature. This two-gap behavior is important in that it is related to the mechanism of the pseudogap. By calculating the electronic Raman spectra we show that this behavior is consistent with the picture in which the d-wave superconducting (SC) order and d-density-wave (DDW) order compete in the phase diagram. In particular, the energy of the B1g peak is determined by both the SC and the DDW orders, increases with underdoping and survives in the DDW normal state. On the other hand, the B2g peak is shown to be sensitive to the SC order alone, and thus vanishes in the normal state (even if in the presence of the DDW order). The doping dependence and the temperature dependence of the peak energies in the two channels accord nicely with recent experimental results, which strongly supports the competing-order point of view for the superconducting and pseudogap phases.
The analytical investigation of the magnetic orientation and hysteresis loop in exchange-spring magnetic multilayers
Authors: Deng Ya  , Zhao Guo-Ping  , Bo Niao  ,   College of Physics and Electronic Engineering, Sichuan Normal University,Chengdu 610068, China
Published: December 2020

Using the interface coupling constant Ji and the soft layer thickness Ls as the main variables, the changes of the magnetic moments with the applied field and the hysteresis loops of Nd2Fe14B/α-Fe trilayers, whose easy axes of all layers lie in the film plane, have been investigated. Analysis shows that Ji has significant influence on the magnetic orientation, the pinning field HP and the coercivity mechanism. When Ls is small, HP equals to HN, where the coercivity mechanism transforms from nucleation to pinning as Ji decreases, whereas for large Ls this trend is reversed. The critical thickness, at which the nucleation field and pinning field detaches, decreases as Ji decreases. When the reduced exchange coupling is considered, the rigid composite magnet appears only when Ls is very small. The reduced exchange coupling leads to a sudden change of angle of magnetization at the interface, which results in the change of the behavior of the trilayers from the single-phase one to the two-phase one and in the decrease of HN, whereas HP increases when Ls is larger.
Magnetostriction-jump effect in〈110〉 oriented Tb0.3Dy0.7Fe1.95 crystal after non-coaxial field annealing
Authors: Zhang Chang-Sheng  , Ma Tian-Yu  , Yan Mi  ,   State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
Published: December 2020

An〈110〉 oriented Tb0.3Dy0.7Fe1.95 rod was annealed under a field of 0.3 T, which was applied 35° away from its axis. Magnetostriction-jump effect of the magnetically annealed crystal was investigated under a series of uniaxial compressive pre-stresses ranging from 0 to 30 MPa. The magnetically annealed crystal possessed much higher saturation magnetostriction λs than the ones without applying any pre-stresses. When the compressive pre-stress was less than 20 MPa, the magnetically annealed specimen still exhibited obvious magnetostriction jump effect, possessing improved saturation magnetostriction λs and enhanced burst magnetostriction λm. A satisfactory magnetostriction as high as 2315×10-6 could be obtained in the annealed crystal with the application of a pre-stress of 20 MPa. Furthermore, under a compressive pre-stress below 5 MPa, the critical field at which the magnetostriction-jump effect occurs also decreased, which was beneficial for low field applications. Difference in the magnetization processes caused by magnetic annealing was revealed through investigating the pre-stress dependences of the burst field Hjump and the distribution width of non-180° domain wall motion. Magnetic force microscopy images showed the changes of magnetic domain configurations induced by field annealing. Effects of the induced additional anisotropy on the magnetostrictive behaviors were also discussed.
Analysis of Y2O3 doped TiO2 films topography prepared by radio frequency magnetron sputtering
Authors: Cao Yue-Hua  , Di Guo-Qing  ,   Jiangsu Key Laboratory of Thin Films, Department of Physics, Soochow University, Suzhou 215006 China
Published: December 2020

Y2O3-TiO2 composite film were deposited on Si substrate at room temperature by means of radio frequency magnetron sputtering. The crystalline state and topography of the film before and after annealing were measured by XRD and AFM, and the mechanism of the film being more compact was discussed. The result revealed that the evenness and compactness of the film can be improved with increasing the sputtering power, which is due to the fact of more Y2O3 filling the pores around TiO2with raising sputtering power, which inhibited the growth of big TiO\-2 grains and improved the evenness and compactness of film. After annealing, XRD pattern indicated that the addition of Y2O3 favors the formation of rutile TiO2 film which has high-dielectric constant.
The design of a quasi-omnidirectional tabulate metamaterial absorber
Authors: Gu Chao  , Qu Shao-Bo  , Pei zhi-Bin  , Gu Wei  , Liu Jia  , Xu Zhuo  ,   (1)Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi’an Jiaotong University, Xi’an 710049, China; (2)Science College, Air Force Engineering University, Xi’an 710051, China; (3)The Engineering&technical College of Chengdu University of Technology Department of Computer Science and Technology, Leshan 614300, China
Published: December 2020

We report the design of a quasi-omnidirectional tabulate metamaterial absorber, which is substantiated on the double-faced absorbing, polarization-insensitive and wide-angle property of the metamaterial cell. Both theoretical and simulated results reveal that our absorber surely has a distinct absorption point with double-faced absorbing property near 6.18 GHz, which is not influenced significantly by the polarization angle and the angle of incidence. The retrieved impedance indicates the electromagnetic resonance of the metamaterial could be tuned to match approximatively the impedance of the free space to suppress the reflectance at the absorption frequency. The distributions of the power loss indicates the strong absorption is mainly due to dielectric loss of the substrates and the design of adopting two different substrates could make the coupling of the front absorber and the back absorber depressed, which effectively suppresses the transmission caused by the coupling. This metamaterial absorber may have applications in many scientific and technological areas.
The electronic structure and infrared spectroscopy of Al-H and Fe-H codoped rutile-type TiO2
Authors: Zhang Zheng-Jie  , Meng Da-Wei  , Wu Xiu-Ling  , Zheng Jian-Ping  , Fan Xiao-Yu  , Liu Wei-Ping  , Huang Li-Wu  , He Kai-Hua  ,   (1)Faculty of Materials Science and Chemical Engineering, Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074, China; (2)Faculty of Maths and Physics, China University of Geosciences, Wuhan 430074, China; (3)State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China
Published: December 2020

Rutile from Shuanghe and Bixiling area in the Dabie Orogen were investigated by Micro- Fourier transform infrared spectroscopy (FTIR). The results show that all the grains exhibit a sharp band near 3280 cm-1 or 3295 cm-1. Two structures have been suggested about the position of H in rutile, namely the chanel center (CC) and basal octahedron edge (BOE) models. The lattice structure and electronic band structure of Al—H and Fe—H codoped rutile TiO2 has been calculated by first-principles method. According to O—H bond vibration frequency of FTIR and O—H…O bond distance between O—O of computational results, we deduce that modified channel center (MCC) model is more reasonable. The calculation results indicate that the t2g state of Fe overlaps with the O 2p state, which will narrow the band gap and lead to red shift in optical absorption spectra.
Mid-infrared spectroscopic properties of geometrically frustrated basic cobalt chlorides
Authors: Liu Xiao-Dong  , Tao Wan-Jun  , Hagihala Masato  , Guo Qi-Xin  , Meng Dong-Dong  , Zhang Sen-Lin  , Zheng Xu-Guang  ,   (1)Department of Physics, College of Science, Tianjin Polytechnic University, Tianjin 300360 China; (2)Department of Physics, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan; (3)Synchrotron Light Application Center & Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502, Japan
Published: December 2020

Three types of FTIR spectrometers were employed to measure the mid-infrared (4000—400 cm-1) absorption spectra of geometrically frustrated hydroxyl cobalt chloride Co2(OH)3Cl, and the intrinsic absorption peaks in the functional group region and fingerprint region were selected and assigned to corresponding vibrational modes according to its known crystal structure. In the assigning process, great emphasis was laid on analyzing the exact experimental data of hydroxyl stretching vibration mode vOH, that is, estimating the free vOH of the Co3—OH group without any hydrogen bond (H-bond), to obtain the red-shift which reflects the formation of an H-band in Co2(OH)3Cl. A 156 cm-1 red-shift is obtained theoretically which demonstrates the presence of non-negligible weak H-bonds, and eventually result in the discovery of the rarely reported trimeric H-bond in the field of crystalline materials, which consists of three independent hydroxyl donors and only one Cl- acceptor. We explained the relative weakness of this kind of hydrogen bond which may have a critical effect on the lattice symmetry and magnetic structure.
Luminescent properties of Eu3+ doped Gd2W2O9 and Gd2(WO4)3 nanophosphors
Authors: Feng Xiao-Hui  , Meng Qing-Yu  , Sun Jiang-Ting  , Lü Shu-Chen  , Sun Li-nan  ,   The Key Laboratory of Advanced Functional Materials and Excited State of Heilongjiang Province, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, China
Published: December 2020

Eu3+ doped Gd2W2O9 and Gd2(WO4)3 nanophosphors with different concentrations were prepared via a co-precipitation method. The structure and morphology of the nanocrystal samples were characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The emission spectra and excitation spectra of the samples were measured, the J-O parameters and the quantum efficiencies of the 5D0 level of Eu3+ of the samples were calculated, and the concentration quenching curves of Eu3+ luminescence in different hosts were given. The study results indicate that similar to the Gd2(WO4)3:Eu, the red emission of Eu3+ 5D0 → 7F2 transition in Gd2W2O9:Eu can also be effectively excited by 395 nm near-UV light and 465 nm blue light. So the Gd2W2O9:Eu red phosphors may have a potential application for white light emitting diodes.
Surface morphology and optical properties of Ta2O5 films prepared by radio frequency sputtering
Authors: Di Guo-Qing  ,   Jiangsu Key Laboratory of Thin Films, Department of Physics, Soochow University, Suzhou 215006, China
Published: December 2020

Ta2O5 films were deposited at room temperature by radio frequency(RF) sputtering with the target of bulk Ta2O5, in Ar or Ar-O2 mixture atmosphere. The reflectivity spectra measured from two sides of a film are compared to evaluate the optical absorption of the film. It is found that the excess optical absorption arises from deficiency in oxygen during sputtering. These defects can be eliminated effectively by selecting adequate Ar-O2 mixture and power for sputtering, and unabsorbing Ta2O5 films with compactness and smoothness can be obtained without annealing.
Preparation and characterization of positive materials LiMn1-xFexPO4(0x<1) for lithium ion batteries
Authors: Yue Min  , Hu She-Jun  , Hou Xian-Hua  , Liang Qi  , Peng Wei  ,   (1)BTR New Energy Materials Inc,Shenzhen 518057,China; (2)School of Physics and Telecommunication Engineering,South China Normal University,Guangzhou 510006, China
Published: December 2020

In this study, a series of phase-pure LiMn1-xFexPO4/C (x=0.2, 0.4, 0.6) cathode materials were successfully synthesized by solid-state method. The structure, particle size, surface morphology and electrochemical properties of these cathode active materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical model cell and cyclic voltammograms (CV). The results indicated that the different atom ratio of Mn/Fe affected its electrochemical preformance. A lithium battery using LiMn0.6Fe0.4PO4 as the active materials of the positive electrode exhibits a high initial charge capacity and discharge capacity of 141.5 mAh g-1 and 125.7 mAh g-1, respectively, and the initial coulombic efficiency is 88.8％. After 25 cycles, it retains 99.8% of the initial discharge capacity at 0.2C rate, showing perfect cyclic property.
Preparationand structure and optical-electrical properties of the Nb/SnO2 composite thin film
Authors: Zeng Le-Gui  , Liu Fa-Min  , Zhong Wen-Wu  , Ding Peng  , Cai Lu-Gang  , Zhou Chuan-Cang  ,   (1)Department of Physics,  School of Physics and Nuclear Energy Engineering,  Key Laboratory of Micro-nano Measurement-Manipulation and
Published: December 2020

The Nb/SnO2 composite thin films were successfully synthesized by sol-gel spin-coating method on glass substrate. The structures and properties of Nb/SnO2 composite thin films were characterized by X-ray diffraction (XRD), scanning electron microscopey (SEM), ultraviolet visible near-infrared spectrophotometry and four-probe method. The effects of Nb doping on structure and optical-electrical properties of the Nb/SnO2 composite thin films were researched. The results indicate that a tetragonal rutile structure is retained when the Nb content is less than 0.99at%, and the nano-particles are distributed homogeneously in the thin films and their size can be controlled in the range of 5—7 nm. The resistivity of Nb/SnO2 composite thin films decreases and then increases when the Nb content is less than 0.99at%, and reaches a very low value of 9.49×10-2 Ω ·cm at 0.37at% Nb. In the range of 400—700 nm visible region, the transmittance of Nb/SnO2 composite thin films is up to 90% when the Nb content is less than 0.99at%, and the optical band gap of Nb/SnO2 composite thin films are in the range of 3.9—4.1 eV. The visible light transmittance of Nb/SnO2 composite thin films significantly reduce at 1.23at% Nb.
Influence of the thickness and cathode material on the performance of the polymer solar cell
Authors: Yu Huang-Zhong  , Wen Yuan-Xin  ,   (1)Department of Physics, South China University of Technology, Guangzhou 510640, China; (2)Department of Physics, South China University of Technology, Guangzhou 510640, China;State Key Lab of Subtropical Building Science, South China University of Technology, Guangzhou 510640, China
Published: December 2020

The solar cells based on the blend of MEH-PPV(poly(2-methoxy-5-(2'-ethylhexyloxy) -1,4-phenylene vinylene)) and PCBM (1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6)C61) as acceptor were fabricated. The thickness dependence of the performance of solar cells was studied. The results showed that the solar cells with active layer thickness of 100 nm have the best performance. Increasing device thickness resulted in an increase of charge recombination and a lowering of the fill factor, which leads to lower overall power conversion efficiency. The reasons for the S-shaped kink in the thick device were also analyzed. Influence of the cathode material on the performance of the devices was discussed. The results showed that the solar cells using LiF/Al as the negative electrode formed ohmic contacts at the cathode and anode, which favored the collecting of the charge, increased the transmission of the charge and the absorption of solar light, and improved the performance of the solar cell.
Comprehensive Survey for the Frontier Disciplines Progress of negative electron affinity GaN photocathode
Authors: Fu Xiao-Qian  , Chang Ben-Kang  , Li Biao  , Wang Xiao-Hui  , Qiao Jian-Liang  ,   Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

GaN is becoming a promising material in ultraviolet detection and vacuum electronic source field for its good performance. High quantum efficiencies of greater than 70% and 30% have been achieved for the opaque mode and transparent mode GaN photocathode, respectively. This paper reviews the progress of GaN photocahtode in three important fields,including structure design, surface cleaning and Cs/O activation, analyzes the key factors influencing the quantum efficiency, and evaluates the prospect for its development.
Minimum entropy cumulation method of pulsar profile
Authors: Zhang Hua  , Xu Lu-Ping  ,   School of Electronic Engineering, Xidian University, Xi’an 710071, China
Published: December 2020

To obtain the cumulation profile of pulsar signal, the traditional method needs to identify its period first, and then fold the signal with the period. This method depends on the accuracy of the period, and it has no evaluation standard for the profile. In this paper we analyze the strong correlation between the cumulation profile and the period, and present a minimum entropy method of pulsar cumulation profile and its verification. Therefore this method is applied to the identification of pulsar cycle. The RXTE data and the simulation data are used to verify the effectiveness of the method.
Lie algebraic approach to vibrational populations of diatomic molecules in infrared laser fields
Authors: Liu Fang  , Wang Jun  , Zhao Juan  , Xu Yan  , Meng Qing-Tian  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014,China
Published: December 2020

In this paper, we study the vibrational populations of diatomic molecules in infrared fields using algebraic approach, and obtain the explicit analytical expression of the transition probability. The influences of frequency, intensity and pulse duration on the vibrational populations, which belong to, respectively, the ground state and the first excited state of vibration in NaCl and LiH molecular systems, are discussed.
Approximate solution for a class of relative rotation nonlinear dynamic model
Authors: Mo Jia-Qi  , Cheng Rong-Jun  , Ge Hong-Xia  ,   (1)Department of Mathematics, Anhui Normal University, Wuhu 241003, China; (2)Faculty of Science, Ningbo University, Ningbo 315211, China; (3)Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China
Published: December 2020

A class of relative rotation nonlinear dynamical model with nonlinear damping force and forcing periodic force is investigated. First, a homotopic mapping is constructed, and then the initial approximate solution is determined. Finally, using the homotopic mapping method, the arbitrarily degree approximation for corresponding model is found.
The delocalization effect of 5f electrons for the actinide elements Th to Es
Authors: Zhu Zheng-He  , Meng Da-Qiao  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

The present work devotes to study the delocalization effect of 5f electrons for the actinide elements Th to Es using the quantum mechanical calculation based on the full symmetry group. Follow the definition of quantum mechanics for delocalization effect, it is founded that the variation of the delocalization energy and atomic volume for elements Th to Es is in the opposite tendency each other. The energy gap of HOMO- LUMO and atomic volume for elements Th to Es is nearly the 1 to 1 mapping, and they are the source and image one another.
The energy levels of positron under molecules XH(X=O, S, Se and Te)and positronium
Authors: Fu Yi-Bei  , Zhu Zheng-He  ,   (1)China Academy of Engineering Physics, Mianyang 621900, China; (2)Institute of Atomic and Molecular Physic, Sichuan University, Chengdu 610065, China
Published: December 2020

The present work devotes to the energy levels of positron under molecules XH(X=O, S, Se and Te)and the relations with nuclear field using Dirac equation based on the full symmetry group. Under these nuclear fields, the energy of positron is about e+=-1.022 MeV. For the lower energy level, the energy of positron is increased with nuclear field; for the higher energy level, the energy of positron is nearly invariant with nuclear field. In this case, it is the three-photon annihilation. The formation of the positronium is in orthopositronium 3S, excited state, followed the conservation of charge parity.
Variational-method analysis of stability of Bose-Fermi mixture
Authors: Chen Hai-Jun  , Li Gao-Qing  , Xue Ju-Kui  ,   (1)Physics and Electronics Engineering College, Longdong University, Qingyang 745000, China; (2)Physics and Electronics Engineering College, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

In one-dimensional trapped Bose-Fermi mixture, described by time-dependent one-dimensional nonlinear equations that are derived from a three-dimensional Bose-Fermi system, we study the effect of atom-interactions on stability using a Gaussian Variational approach. We investigate the stable and the unstable conditions as functions of the atoms number and s-wave scattering length. We find that the interaction between the different species of atoms has significant effect on the stability of Bose-Fermi mixture. We also give critical conditions of the atoms number and s-wave scattering length for both special and general cases.
Quantum teleportation internetworking and routing strategy
Authors: Zhou Xiao-Qing  , Wu Yun-Wen  , Zhao Han  ,   College of Physics Science and Information Engineering, Jishou University, Jishou 416000, China
Published: December 2020

The principle of the quantum switch is introduced by means of entanglement swapping. With the help of quantum switch operating entanglement swapping one by one, quantum correlations between Alice and Bob can be established. Adding entangled particle generator into conventional interconnection equipments, such as switch, and keeping quantum correlations between adjacent devices in the network leisure time, one can upgrade the classic internet to quantum teleportation internet. In quantum teleportation internet, the routing is selected also by utilizing the routing algorithm of classical internet. The routing selection can be synchronized with the establishment of quantum channel in static routing strategy. When the dynamic routing strategy is selected, quantum switch first selects a route to generate a router sequence table and then operates entanglement swapping one by one according to the table to establish the quantum correlations between Alice and Bob.
Analysis of urban human mobility behavior based on random matrix theory
Authors: Xu Zan-Xin  , Wang Yue  , Si Hong-Bo  , Feng Zhen-Ming  ,   Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

Mobile communication applications provide a unique data source for the research of human mobility pattern. Based on the distribution data of urban mobile phone users, in this paper is explored the macroscopic dynamical behavior of urban mobility human by using the method of random matrix theory. The largest eigenvalue and the corresponding eigenvector of mobile phone user data deviate far from the distribution of random matrix. The deviations from random matrix vary with time. We find that the largest eigenvalue corresponds to a whole behavior common to all urban human mobility. The results indicate the temporal trends of the mean of correlation coefficient and the largest eigenvalue. We also find that the spatio temporal evolution of the weight of eigenvector components for the eigenvector corresponding to the largest eigenvalue is very consistent with the fluctuation pattern of the macroscopic behavior of urban human mobility.
Numerical simulation study on effects of alternansbehavior on spiral waves
Authors: Wei Hai-Ming  , Tang Guo-Ning  ,   College of Physics and Technology,Guangxi Normal University,Guilin 541004,China
Published: December 2020

The alternans behavior is considered in the Greenberg-Hasting model of discrete excitable medium. The effect of the alternans behavior on spiral wave is investigated. The numerical results show that when the relevant parameters are appropriately chosen the alternans behavior has a significant influence on spiral waves. For example, the alternans behavior leads to the oscillation of the shape of the spiral wave and to the generation of the breathing spiral wave. The alternans behavior induces the meandering and the drifting of spiral waves, even causes spiral wave to move out of the system. Spiral wave can break up into multiple spiral waves, anti-target wave and spatiotemporal chaos due to the alternans behavior. The phenomena that the alternans behavior leads to the conduction barrier in homogeneous medium and causes spiral wave to break up or vanish, are observed for the first time. The physical mechanisms about these phenomena are briefly analyzed.
Research on branching ratio of B0→π－l+ν l decay
Authors: Zhang Bing-Xin  , Liu Xiao-Jing  , Zhang Bai-Jun  , Hua Zhong  , Xiao Li  , Liu Bing  , Wu Yi-Heng  , Wang Qing-Cai  , Wang Yan  ,   (1)Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; (2)Institute of Physics, Jilin Normal University, Siping 136000, China
Published: December 2020

We choose a correlation function of chiral current to calculate the form factors f+Bπ(q2), f Bπ(q2) and the scalar form factor of f0(q2), thereby we can study the effect of leptonic mass on B0→π－l+ν l (l=e, μ, τ) decay. In this paper, we calculate the branching ratio of B0→π－l+ν l(l=e, μ, τ) decay for the first time, and find the leptonic mssses me and mμ may be ignored, but the heavy leptonic mass mτ may not be ignored and it can affect the branching ratio. The calculation results are consistent with the experimental data.
Luminescence properties of terbium doped oxyfluoride tellurite glasses
Authors: He Wei  , Zhang Yue-Pin  , Wang Jin-Hao  , Wang Shi-Xian  , Xia Hai-Ping  ,   Laboratory of Photo-Electronic Material , Ningbo University , Ningbo 315211 , China
Published: December 2020

Tb-doped oxyfluoride tellurite glasses are synthesized by high-temperature melting method. Densities, transmission and luminescence properties at different concentrations of Tb3+ and Gd3+ ions are investigated. The results indicate that all the samples have good physical properties, especially those with high density. Increasing the concentration of Tb3+ ions has a positive effect on luminescence property. Gd3+ ions could sensitize the luminescence of Tb3+, and the best concentration of Gd3+ is 4mol%.
Density functional study on chirospectra of bruguierols
Authors: Mang Chao-Yong  , Gou Gao-Zhang  , Liu Cai-Ping  , Wu Ke-Chen  ,   (1)Institute of Eastern-Himalaya Biodiversity Research, College of Life Science and Chemistry, Dali University, Dali 671000,China; (2)State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002,China
Published: December 2020

The theoretical investigation of the chiral optics is induive to the elucidation of the optically rotational mechanism and the design of the novel chiral drugs. The optical rotation (OR), the vibrational circular dichroism (VCD),and the electronic circular dichroism (ECD) spectra of a series of newly-found bio-active molecules, bruguierols A—C, are calculated with the gradient-corrected density functional theory method. On the basis of molecular structure, normally vibrational modes and electronic structure, we explore the microscopic origin of molecular chirality and discuss the solvent effects of OR and ECD spectra. The results show that the introduction of OH modulates the molecular chirality. The methyl group and the phenyl group enhance the molecular chirality. The normal vibrations and the electronic transitions on the chiral skeleton play critical roles in producing the chiral spectra. The solvent effect decreases OR and weakens the ECD spectra.
Study on spectroscopic parameters and molecular constants of CS+(X2Σ+) and CS+(A2Π) by MRCI
Authors: Liu Hui  , Xing Wei  , Shi De-Heng  , Zhu Zun-Lue  , Sun Jin-Feng  ,   (1)College of Physics amd Information Engineering, Henan Normal University, Xinxiang 453007, China; (2)College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China
Published: December 2020

The potential energy curves (PECs) of CS+(X2Σ+) and CS+(A2Π) have been investigated using the full valence complete active space self-consistent field (CASSCF) method through the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach over the internuclear separation range from 0.05 to 0.60 nm. In the present calculations, the basis sets for S and C are both aug-cc-pV6Z. The spectroscopic parameters of three main isotopes (12C32S+, 12C33S+, 12C34S+) have been determined. The present D0, De, Re, ωe, ωeχe, αe and Be for 12C32S+(X2Σ+) are 6.4694 eV, 6.5542 eV, 0.14975 nm, 1371.89 cm-1, 7.5746 cm-1, 0.006481 cm-1 and 0.8616 cm-1, respectively; and those for CS+(A2Π) are 4.8460 eV, 4.9084 eV, 0.16449 nm, 1009.31 cm-1, 6.4970 cm-1, 0.006110 cm-1 and 0.7134 cm-1, respectively, which have been compared with those of previous results reported in the literature. And the comparison shows that the present results and the experimental results are in excellent agreement with each other. With the PECs of CS+(X2Σ+) and CS+(A2Π) determined here, the vibrational states for each electronic state are determined when the rotational quantum number J equals zero (J = 0). For the first 30 vibrational states, the vibrational level G(υ), inertial rotation constant Bυ and centrifugal distortion constant Dυ for 12C32S+(X2Σ+) and 12C32S+(A2Π) are evaluated when J = 0, which are in good accordance with the available RKR data.
Calculations of low-lying states of hydrogen atom in strong magnetic field by generalized pseudospectral method
Authors: Yan Jun  , Zeng Si-Liang  , Zou Shi-Yang  , Ni Fei-Fei  , He Jian-Feng  ,   (1)Institute of Applied Physics and Computational Mathematics, Beijing 100088, China; (2)School of Science, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

A very simple and highly accurate method of investigating the behavior of atomic system in a strong magnetic field has been developed based on the generalized pseudospectral discretization. As examples, we present the calculations of the binding energies and quadruple moments for the ground and low-lying excited states of the hydrogen atom in a magnetic field ranging from zero up to 1000 a.u.. The obtained results are found to be in excellent agreement with other high-accuracy theoretical calculations. The present method may be straightforwardly applied to cross electric-magnetic field in an arbitrary orientation.