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DFT investigation of half-metallic ferromagnetic rare earth based spinels MgHo_(2)Z_(4)(Z=S,Se)

Journal of Rare Earths 2024年第1期42卷 121-128,I0005页

作者： Maiza Zanib Mumtaz Manzoor N.A.Noor M.Waqas Iqbal Mazia Asghar H.H.Hegazy A.Laref department of Physics Riphah International UniversityLahore CampusPakistan Research Centre for Advanced materials Science King Khalid UniversityP.O.Box 9004AbhaSaudi Arabia department of Physics Faculty of ScienceKing Khalid UniversityP.O.Box 9004AbhaSaudi Arabia department of Physics and Astronomy College of ScienceKing Saud UniversityRiyadh11451Saudi Arabia

Half-metallic ferromagnetism,mechanical as well as thermoelectric properties for rare earth-based spinels MgHo_(2)Z_(4)(Z=S,Se)were investigated using density functional theory(DFT).Structural optimization was done with Perdew-Burke-Ehrenzorf(PBE)sol-generalized gradient approximation(GGA)to calculate the lattice constant of both spinels comparable to experimental *** addition,Born stability criteria and negative formation energy show that our studied spinels are also structurally and dynamically stable in the cubic *** ferromagnetic(FM)state stability,we also calculated the energy differences among FM,antiferromagnetic(AFM),and non-magnetic(NM)***,Curie temperatures of ferromagnetic phases were also *** used Trans-Blaha improved BeckeJohnson(TB-mBJ)potential functional for electronics as well as magnetic characteristics,which lead to the consistent explanation of half-metallic ferromagnetism,representing the whole band-occupancy in material with exact detail of density of states(DOS).The stable FM state was examined in spinels due to the exchange splitting of Ho cation consisting of p-d hybridizations compatible with the result achieved for electronics band structure and ***,spin magnetic moment was explained in terms of anion,cation,and sharing charge on studied *** addition,the calculated thermoelectric properties clearly show that operation range of these systems may be utilized by future experimental works for identifying the potential applications of these systems.

关键词： Ho-based spinels DFT simulations Mechanical parameters Electronic properties HM ferromagnetism Figure of merit

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Significantly enhanced superconductivity in monolayer FeSe films on SrTiO3（001） via metallic δ-doping

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National Science Review 2024年第3期11卷 119-127页

作者： Xiaotong Jiao Wenfeng Dong Mingxia Shi Heng Wang Cui Ding Zhongxu Wei Guanming Gong Yanan Li Yuanzhao Li Binjie Zuo Jian Wang Ding Zhang Minghu Pan Lili Wang Qi-Kun Xue State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University School of Physics&Information Technology Shaanxi Normal University Beijing Academy of Quantum Information Sciences department of Physics Southern University of Science and Technology International Center for Quantum materials School of Physics Peking University department of Physics The Pennsylvania State University Collaborative Innovation Center of Quantum Matter Hefei National Laboratory

Superconductivity transition temperature（Tc） marks the inception of a macroscopic quantum phase-coherent paired state in fermionic systems. For 2D superconductivity, the paired electrons condense into a coherent superfluid state at Tc, which is usually lower than the pairing temperature, between which intrinsic physics including Berezinskii–Kosterlitz–Thouless transition and pseudogap state are hotly debated. In the case of monolayer FeSe superconducting films on SrTiO3（001）, although the pairing temperature（Tp） is revealed to be 65–83 K by using spectroscopy characterization, the measured zero-resistance temperature（Tc0） is limited to 20 K. Here, we report significantly enhanced superconductivity in monolayer FeSe films by δ-doping of Eu or Al on SrTiO3（001） surface, in which Tc0is enhanced by 12 K with a narrowed transition width ΔTc～8 K, compared with non-doped samples. Using scanning tunneling microscopy/spectroscopy measurements, we demonstrate lowered work function of the δ-doped SrTiO3（001） surface and enlarged superconducting gaps in the monolayer FeSe with improved morphology/electronic homogeneity. Our work provides a practical route to enhance 2D superconductivity by using interface engineering.

关键词： monolayer FeSe interface superconductivity δ-doping zero-resistance temperature superconductivity transition temperature

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An effective strategy to inhibit grain coarsening:Construction of multi-element co-segregated grain boundary complexion

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Journal of Advanced ceramics 2024年第7期13卷 1060-1071页

作者： Le Fu Gabriel Arcuri Wenjun Yu Bohan Wang Zihua Lei Ying Deng Kathryn Grandfield School of Material Science and Engineering Central South UniversityChangsha 410083China Canadian Centre for Electron Microscopy McMaster UniversityHamilton L8S 4L8Canada State Key Laboratory of New ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China department of materials Science and Engineering McMaster UniversityHamilton L8S 4L8Canada

When exposed to moderate to high temperatures,nanomaterials typically suffer from severe grain coarsening,which has long been a major concern that prevents their wider ***,we proposed an effective strategy to inhibit grain coarsening by constructing grain boundary(GB)complexions with multiple codoped dopants,which hindered coarsening from both energetic and kinetic *** demonstrate the feasibility of this strategy,multiple selected dopants were doped into a ZrO_(2)-SiO_(2)nanocrystalline glass ceramic(NCGC)to form GB *** results showed that NCGC was predominantly composed of ZrO_(2)nanocrystallites(NCs)distributed in an amorphous SiO_(2)*** layers of GB complexions(~2.5 nm)were formed between adjacent ZrO_(2)NCs,and they were crystalline superstructures with co-segregated *** addition,a small amount of quartz solid solution was formed,and it adhered to the periphery of ZrO_(2)NCs and bridged the adjacent NCs,acting as a“bridging phase”.The GB complexions and the“bridging phase”synergistically enhanced the coarsening resistance of ZrO_(2)NCs up to 1000°*** findings are important for understanding GB complexions and are expected to provide new insights into the design of nanomaterials with excellent thermodynamic stability.

关键词： Zr_(2)-Si_(2) multi-element co-segregation grain boundary(GB)complexion grain coarsening atom probe tomography(APT)

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Photoluminescence and electrical properties of Eu^3＋-doped Na0.5Bi4.5Ti4O15-based ferroelectrics under blue light excitation

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Frontiers of materials Science 2016年第1期10卷 31-37页

作者： Xing-an JIANG Xiang-ping JIANG Chao CHEN NaTU Yun-jing CHEN Ban-chao ZHANG Jiangxi Key Laboratory of Advanced ceramic materials Department of Materials Science and Engineering Jingdezhen Ceramic Institute Jingdezhen 333001 China

Na0.5Bi4.5-xEuxTi4O15 （NBT-xEu^3＋） ceramics with x= 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 and 0.40 were prepared by conventional ceramics processing. NBT-0.25Eu^3＋ ceramics show the strongest red and orange emissions corresponding to the 5D0 → 7F2 （617 nm） and 5D0→ 7F1 （596 nm） transitions, respectively. The strongest excitation band around 465 nm matches well with the emission wavelength of commercial InGaN-based blue LED chip, indicating that Eu^3＋-doped NBT ceramics may be used as potential environmental friendly red-orange phosphor for W-LEDs application. As an inherent ferroelectric and piezoelectric material, the electrical properties of this potentially multifunctional electro-optical material have been also studied. The introduction of Eu^3＋ distinctly increased the Curie temperature （Tc） of NBT-xEu^3＋ ceramics from 640℃ to 711℃ as x ranges from 0 to 0.40. For higher temperature applications, the electrical conductivity was also investigated. The conduction of charge carriers in hightemperature range originates from the conducting electrons from the ionization of oxygen vacancies. High Tc and low tanδ makes Eu^3＋-doped NBT ceramic also suitable for high temperature piezoelectric sensor applications and electro-optical integration.

关键词： Aurivillius bismuth layered structure photoluminescence electricalproperties multifunctional materials

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半金属氢氧化物材料用于电化学水氧化

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Science China materials 2024年第5期67卷 1551-1558页

作者：王静 Mohammed-Ibrahim Jamesh 高强韩波孙睿敏 Hsien-Yi Hsu 周成冈蔡钊 Faculty of materials Science and Chemistry China University of GeosciencesWuhan430074China School of Energy and Environment Department of Materials Science and EngineeringCity University of Hong KongKowloon TongHong Kong999077China

寻找具有高本征活性的水氧化催化剂材料对许多清洁能源技术的发展至关重要.氢氧化物半导体对析氧反应具有一定的电催化活性.然而,该材料导电性较差,限制着其电催化本征活性的提升.本文提出一种兼具高导电性和高催化活性的半金属氢氧化... 详细信息

寻找具有高本征活性的水氧化催化剂材料对许多清洁能源技术的发展至关重要.氢氧化物半导体对析氧反应具有一定的电催化活性.然而,该材料导电性较差,限制着其电催化本征活性的提升.本文提出一种兼具高导电性和高催化活性的半金属氢氧化物析氧电催化材料.通过阳离子掺杂和阴离子空位协同作用,镍铁水滑石半导体可转化为半金属材料,其电阻率降低了两个数量级.相应半金属氢氧化物阵列电极的电催化活性显著提升,在10 mA cm^(-2)电流密度下其析氧过电势仅为195 mV,Tafel斜率仅为40.9 mV dec^(-1),显著优于商用RuO_(2)催化剂(316 mV,99.6 mV dec^(-1)).原位拉曼光谱和理论计算结果表明,半金属氢氧化物可在较低过电位下转化为羟基氧化物中间体,有助于高价态金属活性位点的形成与稳定,从而提升材料的析氧本征活性.本研究表明,兼具优异导电性和催化活性的半金属氢氧化物可作为先进的电极材料.

关键词： electrocatalyst hydroxide semi-metal electric conductivity intrinsic activity

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Intelligent Design of High Strength and High Conductivity Copper Alloys Using Machine Learning Assisted by Genetic Algor

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Computers, materials & Continua 2024年第4期79卷 1727-1755页

作者： Parth Khandelwal Harshit Indranil Manna Metallurgical&materials Engineering department Indian Institute of TechnologyKharagpurWest Bengal721302India Computer Science&Engineering department Indian Institute of TechnologyKharagpurWest Bengal721302India Vice Chancellor Office Birla Institute of Technology(BIT)MesraRanchiJharkhand835215India

metallic alloys for a given application are usually designed to achieve the desired properties by devising experimentsbased on experience, thermodynamic and kinetic principles, and various modeling and simulation ***, the influence of process parameters and material properties is often non-linear and non-colligative. Inrecent years, machine learning (ML) has emerged as a promising tool to dealwith the complex interrelation betweencomposition, properties, and process parameters to facilitate accelerated discovery and development of new alloysand functionalities. In this study, we adopt an ML-based approach, coupled with genetic algorithm (GA) principles,to design novel copper alloys for achieving seemingly contradictory targets of high strength and high electricalconductivity. Initially, we establish a correlation between the alloy composition (binary to multi-component) andthe target properties, namely, electrical conductivity and mechanical strength. Catboost, an ML model coupledwith GA, was used for this task. The accuracy of the model was above 93.5%. Next, for obtaining the optimizedcompositions the outputs fromthe initial model were refined by combining the concepts of data augmentation andPareto front. Finally, the ultimate objective of predicting the target composition that would deliver the desired rangeof properties was achieved by developing an advancedMLmodel through data segregation and data *** examine the reliability of this model, results were rigorously compared and verified using several independentdata reported in the literature. This comparison substantiates that the results predicted by our model regarding thevariation of conductivity and evolution ofmicrostructure and mechanical properties with composition are in goodagreement with the reports published in the literature.

关键词： Machine learning genetic algorithm solid-solution precipitation strengthening pareto front data augmentation

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BS_(0.5)BNT-based relaxor ferroelectric ceramic/glass-ceramic composites for energy storage

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Journal of Advanced ceramics 2023年第4期12卷 695-710页

作者： Xuhai Shi Kai Li Zong-Yang Shen Junqi Liu Chaoqun Chen Xiaojun Zeng Bo Zhang Fusheng Song Wenqin Luo Zhumei Wang Yueming Li China National Light Industry Key Laboratory of Functional ceramic materials Energy Storage and Conversion Ceramic Materials Engineering Laboratory of Jiangxi ProvinceAdvanced Ceramic Materials Research InstituteSchool of Materials Science and EngineeringJingdezhen Ceramic UniversityJingdezhen 333403China

Relaxor ferroelectric ceramics have very high dielectric constant(e)but relatively low electrical breakdown strength(Eb),while glass-ceramics exhibit higher E,due to the more uniformly dispersed amorphous phases and submicrocrystals/nanocrystals *** to effectively combine the advantages of both relaxor ferroelectric ceramics and glass-ceramics is of great significance for the development of new dielectric materials with high energy storage *** this work,we firstly prepared BaO-SrO-Bi_(2)O_(3)-Na_(2)0-TiO_(2)-Al_(2)O_(3)-SiO_(2)(abbreviated as GS)glass powders,and then fabricated(Ba_(0.3)Sr_(0.7))_(0.5)(Bi_(0.5)Na_(0.5))_(0.5)TiO_(3)+x wt%GS ceramic composites(abbreviated as ***-xGS,x=0,2,6,10,14,16,and 18).Submicrocrystals/nanocrystals with a similar composition to *** were crystalized from the glass,ensuring the formation of uniform core-shell structure in ***-xGS relaxor ferroelectric ceramic/glass-ceramic *** the addition amount of GS was 14 wt%,the composite possessed both high&r(>3200 at 1 kHz)and high E,(~170 kV/cm)at room temperature,and their recoverable energy storage density and efficiency were Wrec=2.1 J/cm’and n=65.2%,*** ***-14GS composite also had several attractive properties such as good temperature,frequency,cycle stability,and fast charge-discharge *** work provides insights into the relaxor ceramic/glass-ceramic composites for pulsed power capacitors and sheds light on the utilization of the hybrid systems.

关键词： relaxor ferroelectrics energy storage ceramics glass-ceramics Bi_(0.5)Na_(0.5)TiO_(3)(BNT) Ba_(0.3)Sr_(0.7)TiO_(3)(BST)

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Wave propagation of a functionally graded plate via integral variables with a hyperbolic arcsine function

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 547-561页

作者： Mokhtar Ellali Mokhtar Bouazza Ashraf M.Zenkour Smart structures Laboratory University of Ain TemouchentAin Temouchent 46000Algeria department of Civil Engineering University Tahri Mohamed of BecharBechar 08000Algeria department of Mathematics Faculty of ScienceKing Abdulaziz UniversityJeddah 21589Saudi Arabia Laboratory of materials and Hydrology(LMH) University of Sidi Bel AbbesSidi Bel Abbes 22000Algeria department of Mathematics Faculty of ScienceKafrelsheikh UniversityKafrelsheikh 33516Egypt

Several studies on functionally graded materials(FGMs)have been done by researchers,but few studies have dealt with the impact of the modification of the properties of materials with regard to the functional propagation of the waves in *** work aims to explore the effects of changing compositional characteristics and the volume fraction of the constituent of plate materials regarding the wave propagation response of thick plates of *** model is based on a higher-order theory and a new displacement field with four unknowns that introduce indeterminate integral variables with a hyperbolic arcsine *** FGM plate is assumed to consist of a mixture of metal and ceramic,and its properties change depending on the power functions of the thickness of the plate,such as linear,quadratic,cubic,and inverse *** utilizing Hamilton’s principle,general formulae of the wave propagation were obtained to establish wave modes and phase velocity curves of the wave propagation in a functionally graded plate,including the effects of changing compositional characteristics of materials.

关键词： FGM plate effects of material properties wave propagation indeterminate integral variables inverse sinus hyperbolic function

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Metal-to-insulator transition in oxide semimetals by anion doping

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Interdisciplinary materials 2024年第3期3卷 358-368页

作者： Haitao Hong Huimin Zhang Shan Lin Jeffrey A.Dhas Binod Paudel Shuai Xu Shengru Chen Ting Cui Yiyan Fan Dongke Rong Qiao Jin Zihua Zhu Yingge Du Scott A.Chambers Chen Ge Can Wang Qinghua Zhang Le Wang Kui-juan Jin Shuai Dong Er-Jia Guo Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijingChina department of Physics&Center of materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijingChina Key Laboratory of Quantum materials and Devices of Ministry of Education School of PhysicsSoutheast UniversityNanjingChina materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTennesseeUSA Physical and Computational Sciences Directorate Pacific Northwest National LaboratoryRichlandWashingtonUSA School of Chemical Biological and Environmental EngineeringOregon State UniversityCorvallisOregonUSA Beijing Advanced Innovation Center for materials Genome Engineering Department of Physical ChemistryUniversity of Science and Technology BeijingBeijingChina Environmental Molecular Sciences Laboratory Pacific Northwest National LaboratoryRichlandWashingtonUSA Songshan Lake materials Laboratory DongguanGuangdongChina

Oxide semimetals exhibiting both nontrivial topological characteristics stand as exemplary parent compounds and multiple degrees of freedom,offering a promise for the realization of novel electronic *** this work,we report the structural and transport phase transition in an oxide semimetal,SrNbO_(3),achieved through effective anion ***,the resistivity increased by more than three orders of magnitude at room temperature upon *** extent of electronic modulation in SrNbO_(3)is strongly correlated with misfit strain,underscoring its phase instability to both chemical doping and crystallographic symmetry *** first-principles calculations,we discern that elevating the level of nitrogen doping induces an upward shift in the conductive bands of SrNbO_(3−δ)N_(δ).Consequently,a transition from a metallic state to an insulating state becomes apparent as the nitrogen concentration reaches a threshold of 1/*** investigation shows effective anion engineering in oxide semimetals,offering pathways for manipulating their physical properties.

关键词： anion doping metal-to-insulator transition oxide semimetal phase transition

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Synthesis and spectral properties of Nd-doped glass-ceramics in SiO_2-CaO-MgO system prepared by sol-gel method

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Journal of Rare Earths 2013年第6期31卷 595-599页

作者： Masoud Eslami Zohreh Hamnabard Ali Nemati materials Science & Engineering department Sharif University of Technology materials Research School Ceramic Group

SiO2-CaO-MgO glass and glass-ceramic powder doped with Nd3＋ were synthesized with sol-gel method. Tetraethylorthosilicate （TEOS）, Ca（NO3）2？4H2O, Mg（NO3）2？6H2O, Nd（NO3）3？6H2O, ethanol, distilled water, and HNO3 were used as starting materials. The synthesized powder’s properties were examined with simultaneous thermal analysis （STA）, X-ray diffraction （XRD）, photoluminescence （PL） and scanning electron microscopy （SEM） analysis. The STA curves showed that the softening point and crystallization temperatures were shifted to higher temperatures with increasing dopant content. Regarding XRD patterns of glass samples, Nd was found to act as an intermediate oxide in glass matrix. The XRD patterns of glass-ceramic samples indicated that bredigite and akermanite crystallized in the glass matrix after heat treating at 900 oC. The fluorescence spectra showed that glass-ceramics emitted much stronger irradiation than glasses with the same dopant content. The SEM images illustrated uniform and homogeneous distribution of applied oxides in glass and glass-ceramic compositions.

关键词： glass glass-ceramic synthesis sol-gel method spectral properties rare earths

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