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Bandgap narrowing and polarization enhancement in(K,Na,Li)(Nb,Sb,Ta)O_(3)+x%Fe_(2)O_(3) lead-free ceramics for photovoltaic applications

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Journal of Advanced Ceramics 2023年第7期12卷 1406-1417页

作者： Jian Chen Jiaxing Mao Zihui Wang Yanhui Dong Jinming Guo Mingkai Li Yi Zhang Yinmei Lu Yunbin He key laboratory of Green Preparation and Application for Functional materials Ministry of EducationHubei Key Lab of Ferro&Piezoelectric Materials and DevicesHubei Key Laboratory of Polymer MaterialsSchool of Materials Science and EngineeringHubei UniversityWuhan 430062China Institute of Photoelectronic Thin Film devices and Technology Tianjin Key Laboratory of Thin Film Devices and TechnologyNankai UniversityTianjin 300350China

The need for ferroelectric materials with both narrow bandgaps(Eg)and large remanent polarization(Pr)remains a key challenge to the development of high-efficiency ferroelectric photovoltaic(FPV)*** this work,[(K_(0.43)Na_(0.57))_(0.94)Li_(0.06)][(Nb_(0.94)Sb_(0.06))_(0.95)Ta_(0.05)]O_(3)(KNLNST)-based lead-free ceramics with narrow Eg and large P are obtained via Fe_(2)O_(3) *** optimizing the level of Fe_(2)O_(3) doping,a KNLNST+1.3%Fe_(2)O_(3) ceramic is fabricated that simultaneously possesses a narrow Eg of 1.74 eV and a large Pr of 27.05μC/cm^(2).These values are much superior to those of undoped KNLNST ceramics(Eg=3.1 eV and Pr=17.73μC/cm^(2)).While the large P stems from the increment of the volume ratio between the orthorhombic and tetragonal phases(Vo/VT)in KNLNST ceramics by proper amount of Fe3+doping,the narrow Eg is attributed to the coupling interaction between the Fe3+dopants and the B-site Sb3+host ***,a switchable photovoltaic effect caused by the ferroelectric depolarization electric field(Edp)is observed in the KNLNST+1.3%Fe_(2)O_(3) ceramic-based *** to the narrower Eg and larger P,of the doped ceramic,the photovoltaic performance of the corresponding device(open-circuit voltage(Voc)=-5.28 V and short-circuit current density(JSC)=0.051μA/cm^(2))under a downward poling state is significantly superior to that of an undoped KNLNST-based device(Voc=-0.46 V and Jse=0.039μA/cm^(2)).This work offers a feasible approach to developing ferroelectric materials with narrow bandgaps and large Pr for photovoltaic applications.

关键词： ferroelectrics bandgap(E_(g)) remanent polarization(P_(r)) photovoltaic effect [(K_(0.43)Na_(0.57))_(0.94)Li_(0.06)][(Nb_(0.94)Sb_(0.06))_(0.95)Ta_(0.05)]O_(3)(KNLNST)

Effect of Ag Addition on the Microstructure and Magnetic Properties of FePt Thin Films

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Journal of Wuhan University of Technology(materials Science) 2008年第5期23卷 670-674页

作者：程晓敏杨晓非 Department of Electronic Science and Technology Huazhong University of Science and Technology key laboratory of ferroelectric and piezoelectric materials and devices of hubei province Hubei University

FePt thin films and [FePt/Ag]n multilayer thin films were prepared by magnetron sputtering technique and subsequent annealing process. By comparing the microstructure and magnetic properties of these two kinds of thin films, effects of Ag addition on the structure and properties of FePt thin films were investigated. Proper Ag addition was found helpful for FePt phase transition at lower annealing temperature. With Ag addition, the magnetic domain pattern of FePt thin film changed from maze-like pattern to more discrete island-like domain pattern in [FePt/Ag]n multilayer thin films. In addition, introducing nonmagnetic Ag hindered FePt grains from growing larger. The in-depth defects in FePt films and [FePt/Ag]n multilayer films verify that Ag addition is attributed to a large number of pinning site defects in [FePt/Ag]n film and therefore has effects on its magnetic properties and microstructure.

关键词： [FePt/Ag]n multilayer thin films FePt thin films coercivity magnetic domain patterns pinning sites

Preparation and study on performance of submicron nickel powder for multilayer chip positive temperature coefficient resistance

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Chinese Physics B 2010年第11期19卷 571-575页

作者：陈勇龚树萍傅邱云郑志平黄日明苏鹏 Department of Electronic Science & Technology Huazhong University of Science & Technology School of Physics and Electronic Technology and key laboratory of ferroelectric and piezoelectric materials and devices of hubei province Hubei University

Base metal nickel is often used as the inner electrode in multilayer chip positive temperature coefficient resistance （PTCR）. The fine grain of ceramic powders and base metal nickel are necessary. This paper uses reducing hydrazine to gain submicron nickel powder whose diameter was 200-300 nm through adjusting the consumption of nucleating agent PVP properly. The submicron nickel powder could disperse well and was fit for co--fired of multilayer chip PTCR. It analyes the submicron nickel powder through x-ray Diffraction （XRD） and calculates the diameter of nickel by PDF cards. Using XRD analyses it obtains several conclusions： If the molar ratio of hydrazine hydrate and nickel sulfate is kept to be a constant, when enlarging the molar ratio of NaOH/Ni^2＋, the diameter of nickel powder would become smaller. When the temperature in the experiment raises to 70-80 ℃, nickel powder becomes smaller too. And if the molar ratio of NaOH/Ni2＋ is 4, when molar ratio of （C2H5O）2/Ni^2＋ increases, the diameter of nickel would reduce. Results from viewing the powders by optical microscope should be the fact that the electrode made by submicron nickel powder has a better formation and compactness. Furthermore, the sheet resistance testing shows that the electrode made by submicron nickel is smaller than that made by micron nickel.

关键词： submicron nickel powder liquid-reduction process positive temperature coefficient (PTC)

Ni-BaTiO_3 interface phenomenon of Co-fired PTCR by aqueous tape casting

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中国有色金属学会会刊：英文版 2007年第6期17卷 1391-1395页

作者：陈勇龚树萍黎慧王法军余石金徐玲芳 Department of Electronic Science and Technology Huazhong University of Science and TechnologyWuhan 430074 key laboratory of ferroelectric and piezoelectric materials and devices of hubei province School of Physics and Electronic TechnologyHubei University

The green sheets with Ni paste as inner electrodes were sintered at 1 320 ℃ for 1 h under a N2/H2 mixing gas at an oxygen partial pressure p(O2)=10-8-10-12 MPa, and then reoxided at 900-1 000 ℃ to form multilayer positive temperature coefficient of resistance(PTCR). During the experiments, electronic characteristic effects of PTC with different thicknesses were contrasted. A certain extending of Ni diffusion is beneficial to the ohmic contact of multilayer PTCR but excessive diffusion is harmful to PTCR. The diffusion was studied by scanning electron microscopy(SEM) and energy-dispersive X-ray spectrometry(EDS). Inter-diffusion of element takes place along the Ni-BaTiO3 interface, especially Ni diffusion to BaTiO3 dominated the process. Furthermore, the degree of Ni diffusion is very severe as ceramic layers are very thin.

关键词： Ni-BaTiO3 阳极温度系数扩散

Dielectric Properties of Bi_4Ti_3O_(12) Ceramics by Impedance Spectroscopic Method

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Journal of Wuhan University of Technology(materials Science) 2016年第5期31卷 977-981页

作者：陈勇 SU Huyin XUE Simin LI Zhaozhi ZHANG Cancan CHEN Qi XU Lingfang 曹万强黄兆祥 School of Physics and Electronic Science Hubei University key laboratory of ferro & piezoelectric materials and devices of hubei province Wuhan 430062 China School of materials Science and Engineering Hubei University Wuhan 430062 China Department of Information Science and Technology Wenhua College Wuhan 430074 China

Various lead-free ceramics have been investigated in search for new high-temperature dielectrics. In particular, Bi_4Ti_3O_（12） is a type of ferroelectric ceramics, which is supposed to replace leadcontaining ceramics for its outstanding dielectric properties in the near future. ferroelectric ceramics of Bi_4Ti_3O_（12） made by conventional mixed oxide route have been studied by impedance spectroscopy in a wide range of temperature. X-ray diffraction patterns show that Bi_4Ti_3O_（12） ceramics are a single-phase of ferroelectric Bi-layered perovskite structure whether it is calcined at 800 ℃ or after sintering production. This study focused on the effect of the grain size on the electric properties of BIT ceramics. The BIT ceramics with different grain sizes were prepared at different sintering temperatures. Grain becomes coarser with the sintering temperature increasing by 50 ℃, relative permittivity and dielectric loss also change a lot. When sintered at 1 100 ℃, r values peak can reach 205.40 at a frequency of 100 k Hz, the minimum dielectric losses of four different frequencies make no difference, all close to 0.027. The values of Ea range from 0.52 to 0.68 e V. The dielectric properties of the sample sintered at 1 100 ℃ are relatively better than those of the other samples by analyzing the relationship of the grain, the internal stresses, the homogeneity and the dielectric properties. SEM can better explain the results of the dielectric spectrum at different sintering temperatures. The results show that Bi_4Ti_3O_（12） ceramics are a kind of dielectrics. Thus, Bi_4Ti_3O_（12） can be used in high-temperature capacitors and microwave ceramics.

关键词： Bi_4Ti_3O_(12) temperature sensitivity permittivity loss(tanδ) activation energy(Ea)

Resistive switching performance improvement of In GaZnO-based memory device by nitrogen plasma treatment

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Journal of materials Science & Technology 2020年第14期47卷 1-6页

作者： Li Zhang Zhong Xu Jia Han Lei Liu Cong Ye Yi Zhou Wen Xiong Yanxin Liu Gang He Faculty of Physics and Electronic Science Hubei UniversityHubei Key Laboratory of Ferro-&Piezoelectric Materials and DevicesHubei Key Laboratory of Applied MathematicsWuhan430062China School of Physics and materials Science Radiation Detection Materials&Device LabAnhui UniversityHefei230039China School of Microelectronics Tianjin Key Laboratory of Imaging and Sensing Microelectronic TechnologyTianjin UniversityTianjin300072China

With the demand of flat panel display development,utilizing the non-volatile memory devices based on indium-gallium-zinc-oxide(IGZO)film may be integrated with IGZO thin film transistors(TFTs)to accomplish system-on-panel *** this work,1×1μm^2 via hole structure IGZO based memory device was fabricated and the resistive switching(RS)behavior was *** inserting a nitrogen doping layer IGZO:N by plasma treatment in Pt/IGZO/Ti N device,highly improved RS performance including lower forming voltage,remarkable uniformity,large memory window of 102,retention property of 10^4 s at 125℃,excellent pulse endurance of 10^7 cycles were *** X-ray photoelectron spectroscopy analysis indicates that plasma doping method can evenly dope nitrogen and induce more non-lattice oxygen in the IGZO *** is deduced that the N atoms of the inserting layer can influence the random formation of oxygen vacancy type conducting filaments,which results in more stable and uniform performance.

关键词： Memory device Resistive switching Plasma treatment Indium-gallium-zinc-oxide Memristor

Growth-Parameter Spaces and Optical Properties of Cubic Boron Nitride Films on Si（001）

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Chinese Physics Letters 2009年第5期26卷 187-190页

作者：范亚明张兴旺游经碧应杰谭海仁陈诺夫 key Lab of Semiconductor materials Science Institute of Semiconductors Chinese Academy Sciences Beijing 100083 key laboratory of ferroelectric and piezoelectric materials and devices of hubei province Hubei University Wuhan 430062

Cubic boron nitride （c-BN） films were deposited on Si（001） substrates in an ion beam assisted deposition （IBAD） system under various conditions, and the growth parameter spaces and optical properties of c-BN films have been investigated systematically. The results indicate that suitable ion bombardment is necessary for the growth of c-BN films, and a well defined parameter space can be established by using the P/a-parameter. The refractive index of BN films keeps a constant of 1.8 for the c-BN content lower than 50%, while for c-BN films with higher cubic phase the refractive index increases with the c-BN content from 1.8 at χc =50% to 2.1 at χc = 90%. Furthermore, the relationship between n and p for BN films can be described by the Anderson-Schreiber equation, and the overlap field parameter γ is determined to be 2.05.

关键词： gamma-ray bursts gamma-rays relativity

A Bulk‑Heterostructure Nanocomposite Electrolyte of Ce_(0.8)Sm_(0.2)O_(2‑δ)-SrTiO_(3) for Low‑Temperature Solid Oxide Fuel Cells

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Nano-Micro Letters 2021年第3期13卷 66-79页

作者： Yixiao Cai Yang Chen Muhammad Akbar Bin Jin Zhengwen Tu Naveed Mushtaq Baoyuan Wang Xiangyang Qu Chen Xia Yizhong Huang State key laboratory for Modification of Chemical Fibers and Polymer materials Key Laboratory of High Performance Fibers and ProductsEngineering Research Center of Technical TextilesMinistry of EducationCollege of Materials Science and EngineeringDonghua University201620 ShanghaiPeople’s Republic of China key laboratory of ferro and piezoelectric materials and devices of hubei province Faculty of Physics and Electronic ScienceHubei UniversityWuhan 430062HubeiPeople’s Republic of China School of materials Science and Engineering Nanyang Technological UniversitySingapore 639798Republic of Singapore

Since colossal ionic conductivity was detected in the planar heterostructures consisting of fluorite and perovskite,heterostructures have drawn great research interest as potential electrolytes for solid oxide fuel cells(SOFCs).However,so far,the practical uses of such promising material have failed to materialize in SOFCs due to the short circuit risk caused by *** this study,a series of fluorite/perovskite heterostructures made of Sm-doped CeO2 and SrTiO3(SDC–STO)are developed in a new bulk-heterostructure form and evaluated as *** prepared cells exhibit a peak power density of 892 mW cm−2 along with open circuit voltage of 1.1 V at 550°C for the optimal composition of 4SDC–*** electrical studies reveal a high ionic conductivity of 0.05–0.14 S cm^−1 at 450–550°C,which shows remarkable enhancement compared to that of simplex *** AC impedance analysis,it has been shown that the small grain-boundary and electrode polarization resistances play the major roles in resulting in the superior ***,a Schottky junction effect is proposed by considering the work functions and electronic affinities to interpret the avoidance of short circuit in the SDC–STO *** findings thus indicate a new insight to design electrolytes for low-temperature SOFCs.

关键词： Bulk-heterostructure SOFC electrolyte Ionic conductivity Schottky junction Work function

Carrier Transport Across Grain Boundaries in Polycrystalline Silicon Thin Film Transistors

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Journal of Wuhan University of Technology(materials Science) 2016年第1期31卷 87-92页

作者：陈勇 ZHANG Shuang 李璋 HUANG Hanhua WANG Wenfeng ZHOU Chao CAO Wanqiang 周郁明 Faculty of Physics&Electronic Science Hubei UniversityWuhan 430062China hubei key laboratory of ferro&piezoelectric materials and devices Wuhan 430062China School of Electrical&Information Engineering Anhui University of TechnologyMaanshan 243002China

We established a model for investigating polycrystalline silicon（poly-Si） thin film transistors（TFTs）.The effect of grain boundaries（GBs） on the transfer characteristics of TFT was analyzed by considering the number and the width of grain boundaries in the channel region,and the dominant transport mechanism of carrier across grain boundaries was subsequently *** is shown that the thermionic emission（TE） is dominant in the subthreshold operating region of TFT regardless of the number and the width of grain *** a poly-Si TFT model with a 1 nm-width grain boundary,in the linear region,thermionic emission is similar to that of tunneling（TU）,however,with increasing grain boundary width and number,tunneling becomes dominant.

关键词： carrier transport grain boundaries thin film transistors polycrystalline silicon