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STATISTICAL APPROXIMATION BASED FINE FREQUENCY SYNCHRONIZATION FOR OFDM SYSTEMS

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Journal of Electronics(China) 2007年第6期24卷 760-764页

作者： Lu Cewu Liu xiaojun kuang Yujun Fang Guangyou Chen Qianbin The Institute of Electronics Chinese Academy of Sciences. Beijing 100080 China

The paper proposes a novel approach for fine frequency synchronization of OFDM syn- chronization systems in multi-path channels. Maximum Likelihood (ML) function of frequency offsets including integral and decimal parts in frequency domain is developed according to the law of great number to eliminate the noise impact of the signal. When the timing delay close to the actual time, the proposed function produces a deep valley indicating frequency offset when large Valley-Square- Error (VSE) appears. Coarse timing offset can also be detected when function’s Valley-Square-Error (VSE) is maximized. Simulation results shows that the proposed algorithm gives very robust estimation of frequency offset, and a coarse timing offset estimation.

关键词： Orthogonal Frequency Division Multiplexing (OFDM) Frequency synchronization Statistical approximation Maximum Likelihood (ML)

Cation Ordering and Phase Competition in Ba8M2+M'65+O24 Hexagonal Perovskite Tantalate and Niobate Dielectrics

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Cation Ordering and Phase Competition in Ba8M2+M'65+O24 Hexa...

Low Temperature Tetragonal Tungsten Bronze Oxides for Li-ion Storage

中国化学会第十届全国无机化学学术会议

作者： xiaojun kuang College of Chemistry and Bioengineering Guilin University of Technology

BaMM’O-type B-cation deficient hexagonal perovskite tantalates and niobates attract attention as microwave dielectric resonators because of their high quality factors and interesting structural chemistry. 8-layer hexagonal perovskite Niobates display twin-shift option and rarely nanometer-scale long-range cation order has been observed in the shifted BaCoNbO, BaZnNbO and BaZnNbO so far. While their Ta-counterparts form exclusively twinned structures. Here we details the correlation of the cation order and phase competition with the B-cationic size and charge differences as well as the bonding preferences associated with the bonding covalence and the second-order Jahn-Teller(SOJT) effect of d Nb and Ta in the BaMM’O hexagonal perovskites. Also we present the Ta-substitution effect on lowering the temperature coefficient of resonant frequency t of 8-lyaer shifted hexagonal perovskite dielectrics toward near-zero t values.

关键词： Microwave dielectric ceramic Hexagonal perovskite cation ordering phase competition

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Chemical Research in Chinese Universities 2024年第5期40卷 922-926页

作者： XU Chengxin ZHANG Wenda LOU Chenjie LI Chengyu XU Ligang SHI Yongchao LIU Jie LUO Huajie FU Jipeng kuang xiaojun TANG Mingxue Guangxi Key Laboratory of Electrochemical and Magnetochemical Function Materials College of Chemistry and BioengineeringGuilin University of TechnologyGuilin541006P.R.China Center for High Pressure Science and Technology Advanced Research Beijing100193P.R.China Guangxi Key Laboratory of Optic and Electronic Materials and Devices Key Laboratory of New Processing Technology for Nonferrous Metals and MaterialsMinistry of EducationCollege of Materials Science and EngineeringGuilin University of TechnologyGuilin541004P.R.China School of Materials Science and Engineering&Key Laboratory of Advanced Materials and Devices for Post-Moore Chips Ministry of EducationUniversity of Science and Technology BeijingBeijing100083P.R.China Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province Institute of Optoelectronic Materials and DevicesChina Jiliang UniversityHangzhou310018P.R.China

Nb-based tungsten bronze oxides have emerged as attractive materials in various fields,owing to the structural openings and simple synthesis *** this work,the tetragonal tungsten bronze(TTB)NaWNbO_(6) was prepared by solid state reaction at a relatively low temperature of 775°*** local structure was systematically studied by solid state nuclear magnetic resonance(SSNMR)with the aid of transition electronic microscopy(TEM).The analysis indicates that NaWNbO6 has pentagonal,square,and triangular ***,square tunnels were partly occupied(50%)by Na,which creates the ability for the Li-ion storage with a volumetric capacity of 210 A·h·L^(−1)at 0.2 *** 2D ^(23)Na-^(23)Na EXSY results further suggest the ability of ions to fast exchange between the tetragonal and pentagonal tunnels,resulting in a high-rate performance 20 C.

关键词： Tetragonal tungsten bronze Solid-state^(23)Na NMR ^(93)Nb NMR spectrum Fast ion exchange

Bismuth-based halide double perovskite Cs_(2)KBiCl_(6): Disorder and luminescence

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Chinese Chemical Letters 2024年第5期35卷 504-508页

作者： Pan Liu Yanming Sun Alberto J.Fernández-Carrión Bowen Zhang Hui Fu Lunhua He Xing Ming Congling Yin xiaojun kuang MOE Key Laboratory of New Processing Technology for Nonferrous Metal and Materials Guangxi Key Laboratory of Optic and Electronic Materials and DevicesCollege of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China Analytical Instrumentation Center College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Spallation Neutron Source Science Center Dongguan 523803China Chinese Academic of Science Institute of PhysicsBeijing National Laboratory for Condensed Matter PhysicsBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China College of Science Guilin University of TechnologyGuilin 541004China College of Chemistry and Bioengineering Guilin University of TechnologyGuilin 541004China

A new bismuth-based halide double perovskite Cs_(2)KBiCl_(6) was isolated successfully through solid-state reactions and investigated using X-ray and neutron *** than an ordered structure,the crystal structure consists of shifted Cs,K,Bi,and Cl sites from the ideal positions with fractional occupancy in compensation,leading to variable local coordination of Cs^(+)ions,as revealed by^(133)Cs solid-state nuclear magnetic resonance ***_(2)KBiCl_(6) displays volume hysteresis at 5-298 K range upon heating and *** Cs_(2)KBiCl_(6) has a direct bandgap of 3.35(2)eV and red-shift luminescence of around 600 nm upon Mn doping compared with the Na *** stabilization of disordered structure in Cs_(2)KBiCl_(6) is related to two factors including the large-sized K^(+)cation which prefers to coordinate with more than six Cl^(-),and the Bi^(3+)with 6s^(2) lone pair which has a preference for a local asymmetric *** findings could have general application and help to understand the structure and property of halide perovskites.

关键词： Halide perovskite Double perovskite Luminescence Disordered structure Direct bandgap

Innovative Lithium Storage Enhancement in Cation-Deficient Anatase via Layered Oxide Hydrothermal Transformation

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Innovative Lithium Storage Enhancement in Cation-Deficient A...

Hybrid coating SnO_(2)for enhanced Li ions storage

中国化学会第十五届固态化学与无机合成学术会议

作者： Fengqi Lu xiaojun kuang College of Materials Science and Engineering Guilin University of Technology

The electrochemical of cation-deficient TiO anatase could enhance significantly with the defect *** soft-chemistry synthetic routes of anatase phases usually require amorphous precursors derived from expensive and air-sensitive alkoxides. Here cation-deficient Nb-doped TiO (NTO,formulated as TiNbO) anatase has been successfully synthesized from layered KTiNbO by one-pot hydrothermal *** Rietveld refinement Neutron powder diffraction (NPD) data suggested that there was 3.8(5)%cationic vacancy in the Nb-doped TiO anatase crystal *** used as an anode of lithium ion batteries (LIBs),the NTO electrode displayed initial discharge and charge capacities of 618 and 384.6 mAh/g at a current density of 0.2 C respectively,with a remarkable discharge capacity maintained at～246.8 m Ah/g after 100 cycles,representing the highest record among the reported Nb-doped TiO anatases under low current.A full cell,fabricated using the NTO electrode as anode and commercial LiCoO cathode,is shown to deliver discharge capacity of 230.2 mAh/g after 15 cycles,which exceeds those for the most previous reported full cells based on the TiO anode and makes this NTO material a promising anode candidate for *** results present a practical synthetic strategy of tuning cationic vacancies through aliovalent cationic substitution to improve the electrochemical performance of actual LIBs and possibly to develop further relevant devices.

关键词： Niobium-doped TiO2 anatase cationic deficiency neutron powder diffraction hydrothermal reaction

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Chinese Chemical Letters 2023年第12期34卷 396-400页

作者： Yanan Gao Jie Liu Chenjie Lou Hailiang Geng Jipeng Fu Chengyu Li Yongjin Chen Cong Wang Wenda Zhang xiaojun kuang Yifan Liu Xiang Gao Mingxue Tang School of Physical Science and Technology Inner Mongolia UniversityHohhot 010000China Center for High Pressure Science and Technology Advanced Research Beijing 100193China Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province Institute of Optoelectronic Materials and DevicesHangzhou 310018China College of Mathematics and Physics Bejing University of Chemical TechnologyBejing 100029China MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materials Guangxi Key Laboratory of Optic and Electronic Materials and DevicesCollege of MaterialsGuilin 541100China

Anode SnO_(2)in lithium-ion batteries suffers from volume expansion and ***,the SnO_(2)nanoparticles are hybrided with ZrO_(2)particles by the support of carbon nanotube *** obtained SnO_(2)/C/ZrO_(2)composite shows improved electrochemical *** reveal that the carbon nanotubes shorten the transmission path of electrons and Li^(+) *** milling with ZrO_(2)promotes the formation of nanosized SnO_(2)to weaken the internal strain change,being beneficial to buffering volume change during electrochemical cycling ***-resolution 6.7Li NMR investigations indicate that conversion and alloying reactions are stepwise involved for SnO_(2)/C/ZrO_(2)*** strategy of designing SnO_(2)/C/ZrO_(2)composite from the morphology-controlled metal-organic frameworks for energy storage widens the possibility to fabricate promising materials with enhanced performances.

关键词： Hybrid regulation Lithium-ion batteries Fast migration Volume confinement Energy storage

A Nonlinear Optical Switchable Sulfate of Ultrawide Bandgap

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CCS Chemistry 2021年第7期3卷 2298-2306页

作者： Yanqiang Li Congling Yin Xiaoyan Yang xiaojun kuang Jie Chen Lunhua He Qingran Ding Sangen Zhao Maochun Hong Junhua Luo State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian 350002 University of Chinese Academy of Sciences Beijing 100049 MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materials Guangxi Key Laboratory of Optical and Electronic Materials and DevicesCollege of Materials Science and EngineeringGuilin University of TechnologyGuilinGuangxi 541004 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190 Songshan Lake Materials Laboratory DongguanGuangdong 523808 Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China FuzhouFujian 350108

Nonlinear optical(NLO)switchable materials have attracted intense attention because of their promising applications in optoelectronic ***,previous studies are mainly limited to molecular-based compounds that usually exhibit narrow ***,we report all-inorganic Li_(9)Na_(3)Rb_(2)(SO_(4))_(7) as an ultrawide-bandgap NLO switchable material.

关键词： ultrawide bandgap NLO optics switchable material phase transition sulfates

Correlating O-deﬁciency and luminescence property of Tb^(3+)þdoped SrO

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Advanced Powder Materials

Advanced Powder Materials 2023年第3期2卷 28-35页

作者： Kaina Wang Jipeng Fu Shuqin Chang Xuan Sun Tianyi Sun Su Zhang Ran Pang Lihong Jiang xiaojun kuang Evan Wenbo Zhao Chengyu Li Shiqing Xu Mingxue Tang Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province Institute of Optoelectronic Materials and DevicesChina Jiliang University310018 HangzhouChina Center for High Pressure Science and Technology Advanced Research 100094 BeijingChina State Key Laboratory of Rare Earth Resources Utilization Changchun Institute of Applied ChemistryChinese Academic of Sciences130022 ChangchunChina Guangxi Key Laboratory of Electrochemical and Magneto-chemical Functional Materials College of Chemistry and BioengineeringGuilin University of TechnologyGuilin 541004PR China Magnetic Resonance Research Center Institute for Molecules and MaterialsRadboud UniversityNijmegen6525AJthe Netherlands

Cubic rock salt can lower down or break the rare earth transition barrier through interstitial or vacancy defects owing to its great deformation and rotationﬂ***,we demonstrate that oxygen vacancies in SrO are induced by proper oxidization and atmosphere adjustment,resulting in defects with various depths and crystalﬁeld *** thermally assisted tunneling from defects to 5 D_(4) state and electronic population decrease on 5 D_(3) state of Tb^(3+)þare observed by the deformation of adjacent oxygen octahedral ***,the asprepared SrO:0.01 Tb^(3+)þphosphors,commercial BaMgAl10O17:Eu^(2+)þblue phosphor,and CaAlSiN3:Eu^(2+)þred phosphor are mixed and coated onto 280 nm deep-ultraviolet LED chip to assemble white light-emitting LED *** LEDs show CCT of 3850 K,4136 K,and 4741 K,with color rendering index of 90.3,90.8,and 92.1,*** insights will advance the fundamental knowledge of crystal engineering in cubic rock salt,and enable new ways to manipulate energy transfer and electronic transition via defects.

关键词： Oxygen vacancy Spectral modulation Long-lasting phosphorescence White LEDs Energy transfer

串联扰动型金属有机框架玻璃的热诱导晶化及结构转变

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硅酸盐学报 2024年第8期52卷 2566-2574页

作者：刘涛殷政匡小军曾明华广西电磁化学功能物质重点实验室桂林理工大学化学与生物工程学院广西桂林541004 药用资源化学与药物分子工程省部共建国家重点实验室广西师范大学化学与药学学院广西桂林541004

晶化行为极大影响玻璃材料的加工赋形及力学、光、电等性能,但晶化过程中微观结构演变机制远不明晰;对于全新类别金属有机框架(MOF)玻璃,相关晶化及高温动态配位化学系统研究更为匮乏。动态高孔穴四重穿插钻石网型MOF–[Co(L1)_(2)]_(4... 详细信息

晶化行为极大影响玻璃材料的加工赋形及力学、光、电等性能,但晶化过程中微观结构演变机制远不明晰;对于全新类别金属有机框架(MOF)玻璃,相关晶化及高温动态配位化学系统研究更为匮乏。动态高孔穴四重穿插钻石网型MOF–[Co(L1)_(2)]_(4n),在水分子配位及热去除多层级协同扰动下可不经高温熔融直接玻璃化。作为首个串联扰动法获得的传统MOF成功玻璃化实例,热重和差热分析发现去水扰动不定形态MOF在T_(g)=560 K处发生玻璃化转变,过冷液体于558~586K间稳定,随后在T_(c)=597 K处发生明显晶化,并进一步在T_(d)=695 K以上发生结构分解;原位变温(PXRD)跟踪并证实了MOF去水无定形→玻璃化→过冷液化→再晶化的相态演变过程;X射线全散射原子对分布函数(PDF)揭示了玻璃态及再晶化态样品的短–中–长程结构特征。基于CCDC数据库结构检索以及铜基同构MOF的合成,结合MOF玻璃晶化相高分辨PXRD谱的Rietveld拟合结构验证,确认了致密六重穿插钻石网MOF–[Co(L_(1))_(2)]_(6n)的生成。MOF过冷液体不同温度淬冷所制备玻璃保有气体可接触孔性并呈现温度依赖变化,揭示了相均一MOF过冷液体内部液态结构差异性。这一研究构建了MOF“晶态–扰动态–过冷液态–玻璃态–晶化态”多相结构演变有趣例证,揭示了MOF玻璃及其过冷液体独特的高温配位自识别和有序化结构自组装行为。

关键词：金属有机框架玻璃结构与相态演变过冷液体晶化气体吸附