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Journal of Advanced Ceramics 2021年第6期10卷 1360-1370页

作者： Ying XIONG Hongyuan XIE Zhenggang RAO Laijun LIU Zhengfeng WANG Chunchun LI College of Information Science and Engineering Guilin University of TechnologyGuilin 541004China guangxi key laboratory of optical and electronic materials and devices College of Material Science and EngineeringGuilin University of TechnologyGuilin 541004China School of materials Science and Engineering Nanchang UniversityNanchang 330031China

AB_(2)O_(4)-type spinels with low relative permittivity(ε_(τ))and high quality factor(Q×f)are crucial to high-speed signal propagation *** this work,Zn^(2+)/Ge^(4+) co-doping to substitute Ga in ZnGa_(2)O_(4) was designed to lower the sintering temperature and adjust the thermal stability of resonance frequency ***_(1+2)Ga_(2-2x)Ge_(x)O_(4)(0.1≤x≤0.5)ceramics were synthesised by the conventional solid state ***^(2+)/Ge^(4+) co-substitution induced minimal variation in the macroscopical spinel structure,which effectively lowered the sintering temperature from 1385 to 1250℃.All compositions crystallized in a normal spinel structure and exhibited dense microstructures and excellent microwave dielectric *** compositional dependent quality factor was related to the microstructural variation,being confirmed by Raman features.A composition with x=0.3 shows the best dielectric properties with ε_(τ) ≈10.09,Q×f≈112,700 THz,and ε_(τ) ≈-75.6 ppm/℃.The negative τf value was further adjusted to be near-zero through the formation of composite ceramics with TiO_(2).

关键词： ceramics spinel composition modulation dielectric properties

Quaternary antiferromagnetic Ba2BiFeS5 with isolated FeS4 tetrahedra

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Chinese Physics B 2019年第8期28卷 329-332页

作者： Shaohua Wang Xiao Zhang Hechang Lei Department of Physics and Beijing key laboratory of Opto-electronic functional materials & Micro-nano devices Renmin University of ChinaBeijing 100872China State key laboratory of Information Photonics and optical Communications & School of Science Beijing University of Posts and TelecommunicationsBeijing 100876China

We report the detailed physical properties of quaternary compound Ba2BiFeS5 with the key structural ingredient of isolated FeS4 *** and heat capacity measurements clearly indicate that Ba2BiFeS5 has a paramagnetic to antiferromagnetic transition at about 30 *** calculated magnetic entropy above ordering temperature is much smaller than theoretical value for high-spin Fe^3+ion with S=5/2,implying the possible short-range antiferromagnetic fluctuation in Ba2BiFeS5.

关键词： isolated FeS4 tetrahedra antiferromagnetic transition short-range antiferromagnetic fluctuation

Investigation of electronic,elastic,and optical properties of topological electride Ca3Pb via first-principles calculations

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Chinese Physics B 2021年第5期30卷 583-588页

作者： Chang Sun Xin-Yu Cao Xi-Hui Wang Xiao-Le Qiu Zheng-Hui Fang Yu-Jie Yuan Kai Liu Xiao Zhang State key laboratory of Information Photonics and optical Communications&School of Science Beijing University of Posts and TelecommunicationsBeijing 100876China Department of Physics and Beijing key laboratory of Opto-electronic functional materials&Micro-nano devices Renmin University of ChinaBeijing 100872China

Electrides are unique materials with the anionic electrons confined to the interstitial sites,expecting important applications in various *** this work,the electronic structure and detailed physical properties of topological electride Ca_(3)Pb are studied *** comparing the crystal structures and band structures of Ca_(3)Pb and Ca_(3)PbO,we find that after removing O^(2-)ions from Ca_(3)PbO,the remaining electrons are confined in the vacancies of the Ca6 octahedra centers,playing the role as anions and forming an additional energy band compared with that of Ca_(3)*** interstitial electrons partially result in the low work function of Ca_(3)***,the calculated mechanic properties imply that Ca_(3)Pb has a strong *** addition,the dielectric functions and optical properties of Ca_(3)Pb are also analyzed.

关键词： density functional theory(DFT) density of states(DOS) work function elastic constant

Tuning of Magnetic Properties of α-RuCl3 Single Crystal by Cr Doping

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Chinese Physics Letters 2020年第6期37卷 90-93页

作者： Yu-Jie Yuan Cheng-He Li Shang-Jie Tian He-Chang Lei Xiao Zhang State key laboratory of Information Photonicsx and optical Communications and School of ScienceBeijing University of Posts and TelecommunicationsBeijing 100876China Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano DevicesRenmin University of ChinaBeijing 100872China

We study the influence of Cr doping on magnetic properties ofα-RuCl3 single crystals in *** increasing Cr content,the c-axial lattice parameter increases gradually,implying that the Cr doping may weaken the interlayer *** magnetism of Ru1-xCrxCl3 single crystals evolves from a long-range AFM order to a possible spin-glass state with Cr *** appearance of a possible spin-glass state can be explained by the introduction of FM interaction by Cr3+ions,which competes with the AFM interaction between Ru3+***,the larger magnetic moment of Cr3+ion with S=3/2 than Ru3+ion with Jeff=1/2 also results in a monotonic increase of the effective moment of Ru1-xCrxCl3 single crystal.

关键词： doping interaction moment

The Valence Band Offset of an Al_(0.17)Ga_(0.83)N/GaN Heterojunction Determined by X-Ray Photoelectron Spectroscopy

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Chinese Physics Letters 2013年第5期30卷 124-126页

作者： WAN Xiao-Jia WANG Xiao-Liang XIAO Hong-Ling WANG Cui-Mei FENG Chun DENG Qing-Wen QU Shen-Qi ZHANG Jing-Wen HOU Xun CAI Shu-Jun FENG Zhi-Hong key lab of Semiconductor materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083 ISCAS-XJTU Joint laboratory of functional materials and devices for Informatics Beijing 100083 School of electronic and Information Engineering Xi’an Jiaotong UniversityXi’an 710049 National key lab of ASIC Shijiazhuang 050051

The valence band offset(VBO)of an Al_(0.17)Ga_(0.83)N/GaN heterojunction is determined to be 0.13±0.07 eV by x-ray photoelectron *** the obtained VBO value,the conduction band offset(CBO)of~0.22 eV is *** results ind... 详细信息

关键词： N/Ga heterojunction spectroscopy

Lasing dynamics study by femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy

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Chinese Physics B 2016年第5期25卷 219-222页

作者：党伟廖清毛鹏程付红兵翁羽翔 key laboratory of Soft Matter Physics Institute of Physics Chinese Academy of Sciences Hebei key lab of Optic-electronic Information and materials College of Physics Science and Technology Hebei University Beijing key laboratory for optical materials and Photonic devices Department of Chemistry Capital Normal University

Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy （FNOPAS） is a versatile technique with advantages of high sensitivity, broad detection bandwidth, and intrinsic spectrum correction func- tion. These advantages should benefit the study of coherent emission, such as measurement oflasing dynamics. In this letter, the FNOPAS was used to trace the lasing process in Rhodamine 6G （R6G） solution and organic semiconductor nano-wires. High-quality transient emission spectra and lasing dynamic traces were acquired, which demonstrates the applicability of FNOPAS in the study of lasing dynamics. Our work extends the application scope of the FNOPAS technique.

关键词： non-collinear optical parametric amplification lasing dynamics Rhodamine 6G organic semicon-ductor nano-wires

Transitional Area of Ce^4+to Ce^3+ in SmxCayCe1-x-yO2-δ with Various Doping and Oxygen Vacancy Concentrations:A GGA+U Study

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Chinese Journal of Structural Chemistry 2018年第2期37卷 198-209页

作者：吴铜伟贾桂霄王晓霞李磊安胜利 School of materials and Metallurgy Inner Mongolia University of Science and Technology The Inner Mongolia Autonomous Region key lab of Novel functional Ceramics and devices

In this work, we perform DFT ＋ U periodic calculations to study geometrical and electronic structures and oxygen vacancy formation energies of SmxCayCe1-x-yO2-δ systems （x = 0.0312, 0.0625, 0.125 and 0.250; y = 0.0312, 0.0625, 0.125 and 0.250; δ = 0.0312, 0.0625, 0.125, 0.250 and 0.50） with different oxygen vacancy and doping concentrations. The calculated results show that the VI-Sm3＋-V2 structures where there is a position relationship of the face diagonal between V1 and V2 both nearest to Sm3＋ have the lowest energy configurations. The study on electronic structures of the SmxCayCe1-x-yO2-δ systems finds that excess electrons arise from oxygen vacancies and are localized on f-level traps of their neighbor Ce, and Ca2＋ and Sm3＋ co-doping effectively restrains the reduction of Ce4＋. In order to avoid the existence of Ce3＋, x and y must be both larger than 0.0625 as δ = 0.125 or δ must be smaller than 0.125 as x = y = 0.0625. The Ce3＋/Ce4＋ change ratio k has an obvious monotonous increase with increasing the vacancy oxygen concentration. The introduction of Sm3＋ decreases k. In addition, the doped Sm3＋ can restrain the reduction of Ce4＋ when the V1-Sm3＋-V2 structure with a face diagonal position relationship in lower reduced atmosphere exists. It need be pointed out that the Sm025Ce07501.5 system should be thought of as a Sm-doped Ce2O3 one.

关键词： cerium oxide oxygen vacancies doping electronic structures GGA+U

Physical simulations and experimental results of 4H-SiC MESFETs on high purity semi-insulating substrates

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Chinese Physics B 2009年第10期18卷 4474-4478页

作者：陈刚柏松李哲洋吴鹏陈征韩平 Jiangsu Provincial key lab of Advanced Photonic and electronic materials Department of Physics Nanjing University National key laboratory of Monolithic Integrated Circuits and Modules Nanjing Electronic Devices Institute

In this paper we report on DC and RF simulations and experimental results of 4H-SiC metal semiconductor field effect transistors （MESFETs） on high purity semi-insulating substrates. DC and small-signal measurements are compared with simulations. We design our device process to fabricate n-channel 4H-SiC MESFETs with 100 #m gate periphery. At 30 V drain voltage, the maximum current density is 440 mA/mm and the maximum transconductance is 33 mS/mm. For the continuous wave （CW） at a frequency of 2 GHz, the maximum output power density is measured to be 6.6 W/mm, with a gain of 12 dB and power-added efficiency of 33.7%. The cut-off frequency （fT） and the maximum frequency （fmax） are 9 GHz and 24.9 GHz respectively. The simulation results of fT and fmax are 11.4 GHz and 38.6 GHz respectively.

关键词： 4H-SiC MESFET simulation microwave

Precision measurements with cold atoms and trapped ions

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Chinese Physics B 2020年第9期29卷 51-69页

作者： Qiuxin Zhang Yirong Wang Chenhao Zhu Yuxin Wang Xiang Zhang Kuiyi Gao Wei Zhang Department of Physics Renmin University of ChinaBeijing 100872China Beijing key laboratory of Opto-electronic functional materials and Micro-nano devices Renmin University of ChinaBeijing 100872China

Recent progresses on quantum control of cold atoms and trapped ions in both the scientific and technological aspects greatly advance the applications in precision measurement. Thanks to the exceptional controllability and versatility of these massive quantum systems, unprecedented sensitivity has been achieved in clocks, magnetometers, and interferometers based on cold atoms and ions. Besides, these systems also feature many characteristics that can be employed to facilitate the applications in different scenarios. In this review, we briefly introduce the principles of optical clocks, cold atom magnetometers, and atom interferometers used for precision measurement of time, magnetic field, and inertial forces. The main content is then devoted to summarize some recent experimental and theoretical progresses in these three applications, with special attention being paid to the new designs and possibilities towards better performance. The purpose of this review is by no means to give a complete overview of all important works in this fast developing field, but to draw a rough sketch about the frontiers and show the fascinating future lying ahead.

关键词： precision measurement optical clock magnetometer force measurement atomic interferometer

Stability enhancement of PbS quantum dots by site-selective surface passivation for near-infrared LED application

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Nano Research 2021年第3期14卷 628-634页

作者： Xinsu Zhang Yujuan Chen Linyuan Lian Zizhen Zhang Yixuan Liu Li Song Chong Geng Jianbing Zhang Shu Xu Tianjin key laboratory of electronic materials and devices School of Electronics and Information EngineeringHebei University of TechnologyTianjin300401China School of optical and electronic Information Huazhong University of Science and TechnologyWuhan430074China

Infrared lead chalcogenide quantum dots(QDs)suffer fast degradation due to the easy oxidation of surface chalcogen ***,we report a trioctylphosphine-mediated surface passivation method to improve the air stability of PbS *** mechanism study reveals an in situ surface reaction,which leads to site-selective passivation of surface S atoms with lead *** surface capping motif sufficiently protects PbS QDs from oxygen and improves their stability as well as quantum efficiency regardless of the QD size and original ligands on surface *** modified PbS QDs display no obvious fluorescence quenching and surface oxidization after 30 days of air *** robust surface capping also provides high compatibility of PbS QDs with polymers for optoelectronic device *** near-infrared LEDs based on the modified PbS QDs display a slight degradation of only 1.47%from the maximum intensity after continuous operation in air for 250 hours(lifetime>10,000 h)at 0.5 W/cm^(2) power density,indicating the surface passivation route is promising strategy for promoting practical optoelectronic application of PbS QDs.

关键词： PbS quantum dot surface modification stability light-emitting diode