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structural and optical properties of green emitting Y_(2)SiO_(5):Tb^(3+) and Gd_(2)SiO_(5):Tb^(3+) nanoparticles for modern lighting applications

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Rare Metals 2021年第11期40卷 3289-3298页

作者： Sitender Singh Devender Singh Department of Chemistry Maharshi Dayanand UniversityRohtak 124001India

The optical and structural properties of Tb^(3+)-doped yttrium and gadolinium oxyorthosilicate(Y_(2)SiO_(5) and Gd_(2)SiO_(5)) phosphors were analyzed.The samples were synthesized via sol-gel combustion method using organic fuel.The phase purity and structural properties of the samples were determined via combined approach of powder X-ray diffraction,Fourier transformation infrared(FTIR) and transmission electron microscopy(TEM).X-ray measurements revel monoclinic crystal lattice with P_(21/c) symmetry for both M_(2)SiO_(5)(pure host) and M_(2)SiO_(5):Tb^(3+)(doped) silicates,irrespective of the nature of metal(Y or Gd),presence or absence of Tb^(3+)in lattice and change in calcination temperature up to 1050℃.FTIR analysis was applied to confirm the bonding of prepared materials.The appearance of bands corresponding to SiO_(4) tetrahedra(880-1020 cm^(-1)) suggest the layered structure and support the diffraction measurements.TEM micrographs confirm the synthesis of spherical nanoparticles with filled morphology,narrow size distribution and slightly agglomerated crystallites of the samples.The elemental composition of prepared materials was determined using energy dispersive X-ray spectroscopy.The spectra show peaks only for elements assimilated within the host framework.The photoluminescence(PL) emission spectra of Tb^(3+)-doped samples show ^(5)D_(4)→^(7)F_(J)(J=3-6) transitions under 254 nm-excitation.The dominant peak at 544 nm for ^(5)D_(4)→^(7)F_(5) transition is responsible for the emission of green light on ultraviolet-visible excitation in both the Tb^(3+)-doped host matrixes.Owing to advantageous properties like intense PL and high crystallinity,these nanophosphors could possess potential applications in the mercury free lighting sources and optoelectronic devices.

关键词： structural Optical Silicates Luminescence Optoelectronic

structural, morphological, dielectrical and magnetic properties of Mn substituted cobalt ferrite

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Journal of Semiconductors 2013年第9期34卷 16-20页

作者： S.P.Yadav S.S.Shinde A.A.Kadam K.Y.Rajpure Karmveer Bhaurao Patil College VashiNavi Mumbai Maharashtra-400703India Electrochemical Materials Laboratory Department of PhysicsShivaji UniversityKolhapur Maharashtra-416004India Smt.Kashibai Navale College of Engineering Wadgaon BkPune Maharashtra-411041 India

The C01-xMnxFez04 （0 ≤ x 〈-5 0.5） ferrite system is synthesized by using an auto combustion technique using metal nitrates. The influence of Mn substitution on the structural, electrical, impedance and magnetic properties of cobalt ferrite is reported. X-ray diffraction patterns of the prepared samples confirm that the Bragg＇s peak belongs to a spinel cubic crystal structure. The lattice constant of cobalt ferrite increases with the increase in Mn content. The microstructural study is carried out by using the SEM technique and the average grain size continues to increase with increasing manganese content. AC conductivity analysis suggests that the conduction is due to small polaron hopping. DC electrical resistivity decreases with increasing temperature for a Col-xMnxFe204 system showing semiconducting behavior. The activation energy is found to be higher in the paramagnetic region than the ferromagnetic region. Curie temperature decreases with Mn substitution in the host ferrite system. Dielectric dispersion having Maxwell-Wagner-type interfacial polarization has been observed for cobalt ferrite samples. Magnetic properties have been studied by measuring M-H plots. The saturation and remanent magnetization increases with Mn substitution.

关键词： combustion Mn substitution structural dielectric magnetic

Influence of structural defects on charge density waves in 1T-TaS_(2)

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Nano Research 2023年第8期16卷 11528-11539页

作者： Iaroslav Lutsyk Karol Szalowski Pawel Krukowski Pawel Dabrowski Maciej Rogala Witold Kozlowski Maxime Le Ster Michal Piskorski Dorota A.Kowalczyk Wojciech Rys Rafal Dunal Aleksandra Nadolska Klaudia Toczek Przemyslaw Przybysz Ewa Lacinska Johannes Binder Andrzej Wysmolek Natalia Olszowska Jacek J.Kolodziej Martin Gmitra Takuma Hattori Yuji Kuwahara Guang Bian Tai-Chang Chiang Pawel J.Kowalczyk Faculty of Physics and Applied Informatics University of LodzPomorska 149/15390-236 LodzPoland Faculty of Physics University of WarsawPasteura 502-093 WarsawPoland Faculty of Physics Astronomyand Applied Computer ScienceJagiellonian UniversityLojasiewicza 1130-348 KrakowPoland National Synchrotron Radiation Centre SOLARIS Jagiellonian UniversityCzerwone Maki 9830-392 KrakówPoland Institute of Physics Faculty of SciencePavol JozefŠafárik University in KošicePark Angelinum 904001 KošiceSlovakia Institute of Experimental Physics Slovak Academy of SciencesWatsonova 4704001 KošiceSlovakia Department of Precision Engineering Graduate School of EngineeringOsaka University2-1 Yamada-okaSuita 565-0871Japan Department of Physics and Astronomy University of MissouriColumbiaMissouri 65211USA Department of Physics and Frederick Seitz Materials Research Laboratory University of Illinois at Urbana-ChampaignUrbanaIllinois 61801-3080USA

The influence of intrinsic defects of 1T-TaS_(2)on charge density waves(CDWs)is studied using scanning tunneling microscopy and spectroscopy(STM,STS),angle-resolved photoelectron spectroscopy(ARPES),and density functional theory(DFT).We identify several types of structural defects and find that most have a local character limited to a single CDW site,with a single exception which effectively behaves as a dopant,leading to band-bending and affecting multiple neighboring sites.While only one type of defect can be observed by STM topographic imaging,all defects are easily resolved in STS mapping.Our results indicate modulation of the Mott band gap commensurate with the CDW and breaking of the three-fold symmetry of electronic states.DFT calculations(with included Coulomb interactions)are used to investigate the electronic structure,focusing on both sulfur vacancy and oxygen-sulfur substitution.The sulfur vacancy system,characterized with a metallic behavior,is identified as the origin of one of the experimentally observed defects.Additionally,the effect of oxidation of 1T-TaS_(2)depends on the substitution site,leading to the heterogeneity of electronic properties.

关键词： structural charge sulfur

structural characteristics of river networks and their relations to basin factors in the Yangtze and Yellow River basins

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Science China(Technological Sciences) 2019年第11期62卷 1885-1895页

作者： CHEN XiaBin WANG YiChu NI JinRen The Key Laboratory of Water and Sediment Sciences Ministry of EducationCollege of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Beijing Innovation Center for Engineering Science and Advanced Technology(BIC-ESAT) Peking UniversityBeijing 100871China

The integration of rivers and basins highly implies the possible existence of certain relationships between hierarchical characteristics of river networks and primary basin factors.Here we investigated river networks in two large basins,the Yangtze River and the Yellow River,characterized with basic factors such as annual precipitation,slope,soil erodibility and vegetation.Hierarchical analysis demonstrated a fair self-similarity of river networks at the stream-order 1-5 in both rivers,described by the structural parameters including bifurcation ratio,side-branching ratio,drainage density,and length of headwater-river.Besides precipitation,basin slope was essential in shaping river networks in both basins,showing a significant positive correlation(R^2=0.39-0.85)to bifurcation ratio,side-branching ratio,and drainage density.Given the same basin slope(5°-15°),the higher soil erodibility and sparse vegetation would promote greater side-branching ratio and drainage density in the Yellow River,which were estimated 11.97%and 63.70%larger,respectively than those in the Yangtze River.This study highlights the importance to formulate basin-specific strategies for water and soil conservation in terms of different structures of river networks.

关键词： river network structural characteristics basin factor Yangtze River Yellow River

structural Design Optimization Using Isogeometric Analysis: A Comprehensive Review

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Computer Modeling in Engineering & Sciences 2018年第12期117卷 455-507页

作者： Yingjun Wang Zhenpei Wang Zhaohui Xia Leong Hien Poh National Engineering Research Center of Novel Equipment for Polymer Processing Key Laboratory of Polymer Processing Engineering(South China University of Technology)Ministry of EducationSchool of Mechanical and Automotive EngineeringSouth China University of TechnologyGuangzhou510641China Department of Civil and Environmental Engineering National University of Singapore 1 Engineering Drive 2E1A 07-03117576Singapore Center for Modeling Simulation and Imaging in Medicine(CeMSIM)Rensselaer Polytechnic InstituteTroyNY 12180USA.

Isogeometric analysis(IGA),an approach that integrates CAE into conventional CAD design tools,has been used in structural optimization for 10 years,with plenty of excellent research results.This paper provides a comprehensive review on isogeometric shape and topology optimization,with a brief coverage of size optimization.For isogeometric shape optimization,attention is focused on the parametrization methods,mesh updating schemes and shape sensitivity analyses.Some interesting observations,e.***.the popularity of using direct(differential)method for shape sensitivity analysis and the possibility of developing a large scale,seamlessly integrated analysis-design platform,are discussed in the framework of isogeometric shape optimization.For isogeometric topology optimization(ITO),we discuss different types of ITOs,e.g.ITO using SIMP(Solid Isotropic Material with Penalization)method,ITO using level set method,ITO using moving morphable com-ponents(MMC),ITO with phase field model,etc.,their technical details and applications such as the spline filter,multi-resolution approach,multi-material problems and stress con-strained problems.In addition to the review in the last 10 years,the current developmental trend of isogeometric structural optimization is discussed.

关键词： Isogeometric analysis structural optimization shape optimization topology optimization sensitivity analysis.

structural, electronic, and mechanical properties of cubic TiO_2:A first-principles study

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Chinese Physics B 2018年第1期27卷 492-500页

作者： Debashish Dash Chandan K Pandey Saurabh Chaudhury Susanta K Tripathy Department of Electrical Engineering National Institute of TechnologySilchar Assam Department of Electronics and Communication Engineering National Institute of TechnologySilchar Assam

We present an analysis of structural, electronic, and mechanical properties of cubic titanium dioxide （TiO2） using an all electron orthogonalzed linear combinations of atomic orbitals （OLCAO） basis set under the framework of density functional theory （DFT）. The structural property, especially the lattice constant a, and the electronic properties such as the band diagram and density of states （DOS） are studied and analyzed. The mechanical properties such as bulk moduli, shear moduli, Young＇s Moduli, and Poison＇s ratio are also investigated thoroughly. The calculations are carried out on shear moduli and anisotropy factor for cubic TiO2. The Vickers hardness is also tested for fluorite and pyrite cubic-structured TiO2. Furthermore, the results are compared with the previous theoretical and experimental results. It is found that DFT- based simulation produces results which are approximation to experimental results, whereas the calculated elastic constants are better than the previous theoretical and experimental values.

关键词： density functional theory cubic TiO2 structural electronic and mechanical properties

structural, Electronic and Optical Properties of BiAl _(x)Ga_(1−x)O_(3) (x=0, 0.25, 0.5 and 0.75)

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Chinese Physics Letters 2011年第8期28卷 285-288页

作者：龚赛王月花赵新印张旻赵娜段益峰 Department of Physics China University of Mining and TechnologyXuzhou 221116

A first principles study using the full potential linearized augmented plane wave(FP-LAPW)method is applied to study the structural,electronic and optical properties of BiAlxGa1−xO3.The results show that the alloys become markedly hard as the Al concentration increases.The calculated structural parameters are in good agreement with the experimental data.The band structure and density of states are obtained,which indicate that BiAlxGa1−xO3 has an indirect band gap.Moreover,the optical properties are calculated and analyzed in detail.It is proposed that BiAl_(x)Ga_(1−x)O_(3) is a promising dielectric material.

关键词： material alloys structural

structural, Optical and Electrical Properties of Evaporated CdSe Films

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Journal of Materials Science & Technology 1995年第2期11卷 97-101页

作者： H.P. Sarma, N.Rangaraan and K.R.Murali(Central Electrochemical Research Institute, Karaikudi -623 006, India) Central Electrochemical research Inst Karaikudi India

CdSe films are of great interest for use in thin film photoelectric devices. A simple chemical precipitation method is adopted for the first time to synthesise CdSe powder. Films on glass obtained at different substrate temperatures TS such as 300, 373, 423 and 473 K have been characterised by X-ray diffraction, optical absorption and Hall measurements.

关键词： CdSe ASTM structural Optical and Electrical Properties of Evaporated CdSe Films

structural TRANSFORMATION AND ITS REVERSIBILITY IN LIQUID Al-13%Si ALLOY AT HIGH TEMPERATURES

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中国有色金属学会会刊：英文版 1998年第2期8卷 55-59页

作者： Wang Weimin Bian Xiufang Qin Jingyu Ye Yifu S.I.Sljusarenko College of Mater ials Science and Engineering Shandong University of TechnologyJi'nan 250061P.R.China Institute for Metal Physics Ukraine Academy of ScienceKievUkraine

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关键词： Al-13%Si alloy structural transformation X-ray diffraction analysis