The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Guofu Wang - One of the best experts on this subject based on the ideXlab platform.
-
Growth, Structure and spectral properties of Cr3+-doped LiMgAl(MoO4)3 crystals with a Disordered Structure
RSC Advances, 2012Co-Authors: Bin Xiao, Yisheng Huang, Lizhen Zhang, Zhoubin Lin, Guofu WangAbstract:In order to obtain new, more efficient tunable laser materials for diode laser-pumping, a laser host material with broad absorption and emission bands is very important. This paper reports on the growth, Structure and spectral properties of Cr3+:LiMgAl(MoO4)3 crystals. The Cr3+:LiMgAl(MoO4)3 crystals were grown using the top-seeded solution growth (TSSG) method from a flux of Li2Mo3O10. The LiMgAl(MoO4)3 crystals crystallize in a triclinic symmetry with the space group P and have a highly Disordered Structure. The investigated spectral properties indicated that the Cr3+-doped LiMgAl(MoO4)3 crystals exhibited broad absorption and emission bands which are attributed to locally Disordered environments around the Cr3+ centers. The spectral properties suggested that Cr3+-doped LiMgAl(MoO4)3 crystals are a potential candidate for a tunable laser crystal material.
-
Structure and spectral properties of Nd3+-doped KBaGd(MoO4)3 crystal with a disorder Structure
CrystEngComm, 2011Co-Authors: Xiangming Meng, Yisheng Huang, Lizhen Zhang, Zhoubin Lin, Guofu WangAbstract:In order to obtain new, more efficient laser materials for diode laser-pumped lasers, the laser host materials with broad absorption bands are very important. This paper reports the Structure and spectral properties of Nd3+ : KBaGd(MoO4)3 crystal. KBaGd(MoO4)3 crystallizes in the monoclinic system with space groupC2/c. The Structure analysis shows that KBaGd(MoO4)3 crystal has a Disordered Structure. The investigation of the spectral properties of Nd3+ : KBaGd(MoO4)3 crystals shows that it exhibits broad absorption and emission bands, which are caused by the Disordered Structure of the KBaGd(MoO4)3 crystal. The broad absorption band is very suitable for diode laser pumping. To sum up the spectral properties of Nd3+ : KBaGd(MoO4)3 crystal, it may be regarded as a potential solid-state laser material for diode laser pumping.
-
Growth and Structure of Nd3+-doped Li3Ba2Y3(WO4)8 crystal with a disorder Structure
CrystEngComm, 2010Co-Authors: Guojian Wang, Yisheng Huang, Lizhen Zhang, Guofu WangAbstract:An Nd3+-doped Li3Ba2Y3(WO4)8 crystal with dimensions up to 32 × 20 × 14 mm3 has been grown by the TSSG method. The Li3Ba2Y3(WO4)8 crystal crystallizes in the monoclinic system with the space group C2/c. The unit cell parameters are a = 5.181(2) A, b = 12.677(7) A, c = 19.161(10) A, β = 92.237(13)° and Z = 2. The Li3Ba2Y3(WO4)8 crystal has a high Structure disorder. The spectral properties of Nd3+-doped Li3Ba2Y3(WO4)8 crystal exhibited broad absorption and emission bands, which are caused by the Disordered Structure of the Li3Ba2Y3(WO4)8 crystal. Therefore, it may be regarded as a laser host material for diode laser pumping.
Vyacheslav A. Trofimov - One of the best experts on this subject based on the ideXlab platform.
-
Conservative finite-difference scheme for the problem of THz pulse interaction with multilevel layer covered by Disordered Structure based on the density matrix formalism and 1D Maxwell's equation.
PloS one, 2018Co-Authors: Vyacheslav A. Trofimov, Irina G. Zakharova, Svetlana A. Varentsova, Dmitry Yu. ZagurskyAbstract:On the basis of the Crank-Nicolson method, we develop a conservative finite-difference scheme for investigation of the THz pulse interaction with a multilevel medium, covered by a Disordered layered Structure, in the framework of the Maxwell-Bloch equations, describing the substance evolution and the electromagnetic field evolution. For this set of the partial differential equations, the conservation laws are derived and proved. We generalize the Bloch invariant with respect to the multilevel medium. The approximation order of the developed finite-difference scheme is investigated and its conservatism property is also proved. To solve the difference equations, which are nonlinear with respect to the electric field strength, we propose an iteration method and its convergence is proved. To increase the computer simulation efficiency, we use the well-known solution of Maxwell's equations in 1D case as artificial boundary condition. It is approximated using Cabaret scheme with the second order of an accuracy. On the basis of developed finite-difference scheme, we investigate the broadband THz pulse interaction with a medium covered by a Disordered Structure. This problem is of interest for the substance detection and identification. We show that the Disordered Structure dramatically induces an appearance of the substance false absorption frequencies. We demonstrate also that the spectrum for the transmitted and reflected pulses becomes broader due to the cascade mechanism of the high energy levels excitation of molecules. It leads to the substance emission at the frequencies, which are far from the frequency range for the incident pulse spectrum. Time-dependent spectral intensities at these frequencies are weakly disturbed by the Disordered cover and, hence, they can be used for the substance identification.
-
Substance identification by pulsed THz spectroscopy in the presence of Disordered Structure
Terahertz Emitters Receivers and Applications VIII, 2017Co-Authors: Vyacheslav A. Trofimov, Irina G. Zakharova, Svetlana A. VarentsovaAbstract:We discuss an effective method for the detection and identification of a substance, covered by a Disordered Structure, using the pulsed THz signal. The insufficiency of the standard THz-TDS method, based on the comparison of substance absorption spectra from database with the absorption spectrum of the substance under investigation, is demonstrated. To explain a physical mechanism of false absorption lines appearance in the signal we make a computer simulation on the base of 1D Maxwell's equations and density matrix formalism. For the detection and identification of substance we propose to utilize substance emission at high frequencies corresponding to the high energy levels excitation under the THz pulse action due to the cascade mechanism. In the case of a non-resonant medium we also discuss second harmonic generation and a possibility of its application to the substance detection and identification. The proposed method of the substance detection and identification is based on time-dependent integral correlation criteria calculated with the help of the spectral dynamics of medium response. A new type of the integral correlation criterion, which is less dependent on spectral characteristics of the noisy signal under investigation, is used for the identification.
-
Pulsed THz TDS of objects covered by Disordered Structure
Detection and Sensing of Mines Explosive Objects and Obscured Targets XXI, 2016Co-Authors: Vyacheslav A. Trofimov, Irina G. Zakharova, Dmitry Yu. Zagursky, Svetlana A. VarentsovaAbstract:Using both computer simulation and physical experiment, we demonstrate principal limitations of standard Time Domain Spectroscopy based on a broadband THz pulse for the detection and identification of substance placed inside the Disordered Structure. The interaction of a THz pulse with a Disordered layered Structure was simulated in order to show the influence of the Disordered layers on the spectral characteristics of the transmitted and reflected signals. Spectral characteristics of these signals were analyzed in a direct comparison with the incident pulse spectrum. We showed that a Disordered Structure disturbs the reflected pulse spectrum dramatically. To avoid this, we used the integral correlation criteria in real experiment. Computer simulation results were confirmed by physical experiment. We provided the experiments with paper bag, and ordinary sheets of paper, and napkins.
-
THz TDS of substance covered by Disordered Structure
Photonic Crystal Materials and Devices XII, 2016Co-Authors: Vyacheslav A. Trofimov, Dmitry Yu. Zagursky, Irina G. ZakharovaAbstract:Computer simulation of a few-cycle pulse interaction with a substance covered by Disordered Structure is performed in order to study the effects imposed on spectra of transmitted and reflected pulses by presence of the cover. The substance is described by semi-classic approach and the cover is described by classic electrodynamics equations for linear isotropic medium. The cover consists of a number of layers with different properties which is considered to be the cause of the distortions. The influence of relation between pulse wavelength and cover layer thickness is illustrated. Computer simulation results are compared with those of physical experiments conducted for paper and other common materials.
Yi Xie - One of the best experts on this subject based on the ideXlab platform.
-
Vacancy cluster-induced local Disordered Structure for the enhancement of thermoelectric property in Cu2ZnSnSe4
Journal of Materials Chemistry A, 2021Co-Authors: Weihui Zhang, Chenxi Zhao, Chong Xiao, Yi XieAbstract:Low thermal conductivity is commonly seen in amorphous or Disordered systems, in which electrical conductivity is also very low, bringing considerable obstacles to the development of high-performance thermoelectric materials. Present study highlights the vacancy cluster-induced local Disordered Structure in Cu2ZnSnSe4 for the simultaneous achievement of low thermal conductivity and high electrical conductivity, thereby significantly enhancing its thermoelectric property. Comprehensive evidences from positron annihilation and HRTEM characterizations indicated that the vacancies in cation-deficient (VCu, VZn, and VSn) samples existed as vacancy clusters containing both cation vacancies and intrinsic Se vacancies, which induced the formation of localized disorderly oriented domains. These cation deficiencies contributed to the improved electrical conductivity and power factor of the corresponding Cu2(1−x)Zn1−ySn1−zSe4 samples via an increase in the hole carrier concentration. Moreover, the induced local disordering contributed to further reduced thermal conductivity via stronger phonon scattering. As a result, enhanced ZT performance was achieved in all cation deficient samples. Among them, Sn-deficient Cu2ZnSnSe4 obtained the highest ZT value of 0.44 at 750 K, which was two times larger than that of pristine sample (ZT = 0.14 at 750 K). The cation–anion vacancy cluster and local Disordered Structure elucidated in the present work open up a new avenue to tackle the entanglement of thermoelectric parameters by proper vacancy modulation.
-
metallic nickel nitride nanosheets realizing enhanced electrochemical water oxidation
Journal of the American Chemical Society, 2015Co-Authors: Pengzuo Chen, Yun Tong, Hui Ding, Wangsheng Chu, Zhenmeng Peng, Yi XieAbstract:Exploring efficient and inexpensive oxygen evolution reaction (OER) electrocatalysts is of great importance for various electrochemical energy storage and conversion technologies. Ni-based electrocatalysts have been actively pursued because of their promising activity and earth abundance. However, the OER efficiency for most of the developed Ni-based electrocatalysts has been intrinsically limited due to their low electrical conductivity and poor active site exposure yield. Herein, we report metallic Ni3N nanosheets as an efficient OER electrocatalyst for the first time. The first-principles calculations and electrical transport property measurements unravel that the Ni3N is intrinsically metallic, and the carrier concentration can be remarkably improved with dimensional confinement. The EXAFS spectra provide solid evidence that the Ni3N nanosheets have Disordered Structure resultant of dimensional reduction, which then could provide more active sites for OER. Benefiting from enhanced electrical conductiv...
-
controllable disorder engineering in oxygen incorporated mos2 ultrathin nanosheets for efficient hydrogen evolution
Journal of the American Chemical Society, 2013Co-Authors: Junfeng Xie, Jiajia Zhang, Fabian Grote, Xiaodong Zhang, Hao Zhang, Ruoxing Wang, Yong Lei, B C Pan, Yi XieAbstract:Molybdenum disulfide (MoS2) has emerged as a promising electrocatalyst for catalyzing protons to hydrogen via the so-called hydrogen evolution reaction (HER). In order to enhance the HER activity, tremendous effort has been made to engineer MoS2 catalysts with either more active sites or higher conductivity. However, at present, synergistically structural and electronic modulations for HER still remain challenging. In this work, we demonstrate the successfully synergistic regulations of both structural and electronic benefits by controllable disorder engineering and simultaneous oxygen incorporation in MoS2 catalysts, leading to the dramatically enhanced HER activity. The Disordered Structure can offer abundant unsaturated sulfur atoms as active sites for HER, while the oxygen incorporation can effectively regulate the electronic Structure and further improve the intrinsic conductivity. By means of controllable disorder engineering and oxygen incorporation, an optimized catalyst with a moderate degree of ...
Irina G. Zakharova - One of the best experts on this subject based on the ideXlab platform.
-
Conservative finite-difference scheme for the problem of THz pulse interaction with multilevel layer covered by Disordered Structure based on the density matrix formalism and 1D Maxwell's equation.
PloS one, 2018Co-Authors: Vyacheslav A. Trofimov, Irina G. Zakharova, Svetlana A. Varentsova, Dmitry Yu. ZagurskyAbstract:On the basis of the Crank-Nicolson method, we develop a conservative finite-difference scheme for investigation of the THz pulse interaction with a multilevel medium, covered by a Disordered layered Structure, in the framework of the Maxwell-Bloch equations, describing the substance evolution and the electromagnetic field evolution. For this set of the partial differential equations, the conservation laws are derived and proved. We generalize the Bloch invariant with respect to the multilevel medium. The approximation order of the developed finite-difference scheme is investigated and its conservatism property is also proved. To solve the difference equations, which are nonlinear with respect to the electric field strength, we propose an iteration method and its convergence is proved. To increase the computer simulation efficiency, we use the well-known solution of Maxwell's equations in 1D case as artificial boundary condition. It is approximated using Cabaret scheme with the second order of an accuracy. On the basis of developed finite-difference scheme, we investigate the broadband THz pulse interaction with a medium covered by a Disordered Structure. This problem is of interest for the substance detection and identification. We show that the Disordered Structure dramatically induces an appearance of the substance false absorption frequencies. We demonstrate also that the spectrum for the transmitted and reflected pulses becomes broader due to the cascade mechanism of the high energy levels excitation of molecules. It leads to the substance emission at the frequencies, which are far from the frequency range for the incident pulse spectrum. Time-dependent spectral intensities at these frequencies are weakly disturbed by the Disordered cover and, hence, they can be used for the substance identification.
-
Substance identification by pulsed THz spectroscopy in the presence of Disordered Structure
Terahertz Emitters Receivers and Applications VIII, 2017Co-Authors: Vyacheslav A. Trofimov, Irina G. Zakharova, Svetlana A. VarentsovaAbstract:We discuss an effective method for the detection and identification of a substance, covered by a Disordered Structure, using the pulsed THz signal. The insufficiency of the standard THz-TDS method, based on the comparison of substance absorption spectra from database with the absorption spectrum of the substance under investigation, is demonstrated. To explain a physical mechanism of false absorption lines appearance in the signal we make a computer simulation on the base of 1D Maxwell's equations and density matrix formalism. For the detection and identification of substance we propose to utilize substance emission at high frequencies corresponding to the high energy levels excitation under the THz pulse action due to the cascade mechanism. In the case of a non-resonant medium we also discuss second harmonic generation and a possibility of its application to the substance detection and identification. The proposed method of the substance detection and identification is based on time-dependent integral correlation criteria calculated with the help of the spectral dynamics of medium response. A new type of the integral correlation criterion, which is less dependent on spectral characteristics of the noisy signal under investigation, is used for the identification.
-
Pulsed THz TDS of objects covered by Disordered Structure
Detection and Sensing of Mines Explosive Objects and Obscured Targets XXI, 2016Co-Authors: Vyacheslav A. Trofimov, Irina G. Zakharova, Dmitry Yu. Zagursky, Svetlana A. VarentsovaAbstract:Using both computer simulation and physical experiment, we demonstrate principal limitations of standard Time Domain Spectroscopy based on a broadband THz pulse for the detection and identification of substance placed inside the Disordered Structure. The interaction of a THz pulse with a Disordered layered Structure was simulated in order to show the influence of the Disordered layers on the spectral characteristics of the transmitted and reflected signals. Spectral characteristics of these signals were analyzed in a direct comparison with the incident pulse spectrum. We showed that a Disordered Structure disturbs the reflected pulse spectrum dramatically. To avoid this, we used the integral correlation criteria in real experiment. Computer simulation results were confirmed by physical experiment. We provided the experiments with paper bag, and ordinary sheets of paper, and napkins.
-
THz TDS of substance covered by Disordered Structure
Photonic Crystal Materials and Devices XII, 2016Co-Authors: Vyacheslav A. Trofimov, Dmitry Yu. Zagursky, Irina G. ZakharovaAbstract:Computer simulation of a few-cycle pulse interaction with a substance covered by Disordered Structure is performed in order to study the effects imposed on spectra of transmitted and reflected pulses by presence of the cover. The substance is described by semi-classic approach and the cover is described by classic electrodynamics equations for linear isotropic medium. The cover consists of a number of layers with different properties which is considered to be the cause of the distortions. The influence of relation between pulse wavelength and cover layer thickness is illustrated. Computer simulation results are compared with those of physical experiments conducted for paper and other common materials.
Dmitry Yu. Zagursky - One of the best experts on this subject based on the ideXlab platform.
-
Conservative finite-difference scheme for the problem of THz pulse interaction with multilevel layer covered by Disordered Structure based on the density matrix formalism and 1D Maxwell's equation.
PloS one, 2018Co-Authors: Vyacheslav A. Trofimov, Irina G. Zakharova, Svetlana A. Varentsova, Dmitry Yu. ZagurskyAbstract:On the basis of the Crank-Nicolson method, we develop a conservative finite-difference scheme for investigation of the THz pulse interaction with a multilevel medium, covered by a Disordered layered Structure, in the framework of the Maxwell-Bloch equations, describing the substance evolution and the electromagnetic field evolution. For this set of the partial differential equations, the conservation laws are derived and proved. We generalize the Bloch invariant with respect to the multilevel medium. The approximation order of the developed finite-difference scheme is investigated and its conservatism property is also proved. To solve the difference equations, which are nonlinear with respect to the electric field strength, we propose an iteration method and its convergence is proved. To increase the computer simulation efficiency, we use the well-known solution of Maxwell's equations in 1D case as artificial boundary condition. It is approximated using Cabaret scheme with the second order of an accuracy. On the basis of developed finite-difference scheme, we investigate the broadband THz pulse interaction with a medium covered by a Disordered Structure. This problem is of interest for the substance detection and identification. We show that the Disordered Structure dramatically induces an appearance of the substance false absorption frequencies. We demonstrate also that the spectrum for the transmitted and reflected pulses becomes broader due to the cascade mechanism of the high energy levels excitation of molecules. It leads to the substance emission at the frequencies, which are far from the frequency range for the incident pulse spectrum. Time-dependent spectral intensities at these frequencies are weakly disturbed by the Disordered cover and, hence, they can be used for the substance identification.
-
Pulsed THz TDS of objects covered by Disordered Structure
Detection and Sensing of Mines Explosive Objects and Obscured Targets XXI, 2016Co-Authors: Vyacheslav A. Trofimov, Irina G. Zakharova, Dmitry Yu. Zagursky, Svetlana A. VarentsovaAbstract:Using both computer simulation and physical experiment, we demonstrate principal limitations of standard Time Domain Spectroscopy based on a broadband THz pulse for the detection and identification of substance placed inside the Disordered Structure. The interaction of a THz pulse with a Disordered layered Structure was simulated in order to show the influence of the Disordered layers on the spectral characteristics of the transmitted and reflected signals. Spectral characteristics of these signals were analyzed in a direct comparison with the incident pulse spectrum. We showed that a Disordered Structure disturbs the reflected pulse spectrum dramatically. To avoid this, we used the integral correlation criteria in real experiment. Computer simulation results were confirmed by physical experiment. We provided the experiments with paper bag, and ordinary sheets of paper, and napkins.
-
THz TDS of substance covered by Disordered Structure
Photonic Crystal Materials and Devices XII, 2016Co-Authors: Vyacheslav A. Trofimov, Dmitry Yu. Zagursky, Irina G. ZakharovaAbstract:Computer simulation of a few-cycle pulse interaction with a substance covered by Disordered Structure is performed in order to study the effects imposed on spectra of transmitted and reflected pulses by presence of the cover. The substance is described by semi-classic approach and the cover is described by classic electrodynamics equations for linear isotropic medium. The cover consists of a number of layers with different properties which is considered to be the cause of the distortions. The influence of relation between pulse wavelength and cover layer thickness is illustrated. Computer simulation results are compared with those of physical experiments conducted for paper and other common materials.