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Tuning structural,electrical,dielectric and magnetic properties of Mg-Cu-Co ferrites via dysprosium(Dy^(3+))doping

Journal of Rare Earths 2024年第1期42卷 137-146,I0005页

作者： Maria Akhtar M.s.Hasan nasir Amin n.A.Morley Muhammad Imran Arshad Department of Physics Government College UniversityFaisalabad38000Pakistan Department of Physics The University of Lahore53700Pakistan Department of Materials science and Engineering The University of SheffieldS13JDUK Department of Physics&Astronomy University College LondonUK

In current research work,Dy3+substituted Mg0.5Cu0.25Co0.25Fe2-xDyxO4(0.0≤x≤0.04 with the step interval of 0.01)soft ferrites were synthesized by the sol-gel auto combustion *** prepared samples were characterized by the techniques using X-ray diffraction(XRD),scanning electron microscopy(sEM),energy dispersive X-ray spectroscopy(eds),Fourier transform infrared(FTIR)spectroscopy,curre nt-voltage(Ⅰ-Ⅴ)measurement,LCR meter,vibrating sample magnetometer(VsM)and *** data reveal that the average crystallite size is 49.71 nm and the lattice constant is 0.83703 nm for sample x=*** non-uniform grain growth was demonstrated by micrographs and impurity-free elemental composition was observed from EDX *** DC resistivity has an increasing and decreasing trend in ferromagnetic and paramagnetic regions with an increase in ***,the high resistivity is observed with the order of 1010Ω·cm,and the activation energy is 0.944 eV for samples x=*** dielectric parameters including dielectric constant,dielectric losses,and impedance gradually decrease with the increase in frequency from 8 Hz to 8 *** minimum dielectric loss at high frequency is found for sample x=*** coercivity(Hc)and saturation magnetization(Ms)are found in the ranges of 520.82-544.02 Oe and 20.5841-21.1473 emu/g,*** observations confirm that dysprosium(x=0.03)doped MCC-soft ferrites may be applicable in transformer cores,microwave absorbance,and telecommunication devices.

关键词： soft ferrites DC resistivity Dielectric loss Impedance Coercivity Rare earths

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Antibacterial HA-coatings on bioresorbable Mg alloy

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Journal of Magnesium and Alloys 2024年第5期12卷 1965-1985页

作者： K.V.nadaraia D.V.Mashtalyar M.A.Piatkova A.I.Pleshkova I.M.Imshinetskiy M.s.Gerasimenko E.A.Belov V.V.Kumeiko D.n.Kozyrev K.A.Fomenko V.V.Mostovaya B.R.Torpanov A.R.Biktimirov I.s.Osmushko s.L.sinebryukhov s.V.Gnedenkov Institute of Chemistry FEB RAs 159 Pr.100-letiya VladivostokaVladivostok 690022Russia Far Eastern Federal University 10 Ajax BayRussky IslandVladivostok 690922Russia A.V.Zhirmunsky national scientific Center of Marine Biology FEB RAs 17 St.PalchevskogoVladivostok 690041Russia Regional Clinical Dermatovenerological Dispensary 18 V St.GamarnikaVladivostok 690033Russia nMIC“Treatment and Rehabilitation Center” 3 Ivankovskoe highwayMoscow 125367Russia

In this study,a calcium-phosphate coating was formed on a Mg-Mn-Ce alloy by the plasma electrolytic oxidation(PEO).The antibiotic vancomycin,widely used in the treatment of infections caused by staphylococcus aureus(***),was impregnated into the *** with vancomycin showed high bactericidal activity against *** mechanical and electrochemical properties of the formed coatings were studied,as well as in vitro cytotoxicity tests and in vivo tests on mature male rats were *** to sEM,eds,XRD and XPs data,coatings had a developed morphology and contained hydroxyapatite,which indicates high *** analysis of roughness of coatings without and with vancomycin did not reveal any differences,confirming the high roughness of the *** electrochemical tests,an increase in corrosion resistance by more than two times after the application of PEO coatings was *** to the results of an in vivo study,after 28 days of the implantation of samples with calcium phosphate PEO coating and vancomycin,no signs of inflammation were observed,while an inflammatory reaction developed in the area of implantation of bare alloy,followed by *** release tests from the coatings show a sharp decrease in the concentration of the released antibiotic on day 7 and then a gradual decrease until day *** the experiment,no significant deviations in the condition and behavior of the animals were observed;clinical tests did not reveal a systemic toxic reaction.

关键词： Bioactive coatings Biocompatibility Mg alloy Plasma electrolytic oxidation Hydroxyapatite Vancomycin

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Effect of Ta_(2)O_(5)nanoparticles on bioactivity,composition,structure,in vitro and in vivo behavior of PEO coatings on Mg-alloy

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Journal of Magnesium and Alloys 2024年第6期12卷 2360-2379页

作者： D.V.Mashtalyar I.M.Imshinetskiy V.V.Kashepa K.V.nadaraia M.A.Piatkova A.I.Pleshkova K.A.Fomenko A.Yu.Ustinov s.L.sinebryukhov s.V.Gnedenkov Institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok690022Russia Far Eastern Federal University Vladivostok690950Russia Regional Clinical Dermatovenerological Dispensary Vladivostok690033Russia

The present study investigates the physical and chemical characteristics,behavior in vitro and in vivo,and biocompatibility of coatings containing Ta_(2)O_(5),which are obtained by plasma electrolytic oxidation(PEO)on MA8 magnesium *** obtained coatings demonstrate in vivo biocompatibility and in vitro *** to the base PEO coating,the layers containing Ta_(2)O_(5)facilitate the development of apatite in simulated body fluid,suggesting that the inclusion of nanoparticles improves bioactivity of the *** was found that incorporation of Ta_(2)O_(5)nanoparticles increases roughness and porosity of the formed layers by increasing particle concentration in electrolytes for the PEO process contributing to sufficient soft tissue ingrowth in *** on in vivo studies,these coatings also provide favorable tissue response and minimal inflammatory reaction in comparison with the bare magnesium alloy due to protection of living tissues from deleterious corrosion events of magnesium implant such as local alkalization and intense hydrogen *** results obtained in the present study concluded biocompatibility,tissue integration of the PEO coatings containing Ta_(2)O_(5)nanoparticles making them a promising protective layer for biodegradable magnesium implants.

关键词： Plasma electrolytic oxidation Bioactive coatings Tantalum pentoxide simulated body fluid(sBF) Apatite formation Histology

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synthesis of coral-like structures of Pr-Yb co-doped YIG: structural,optical, magnetic and antimicrobial properties

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Journal of Rare Earths 2024年第3期42卷 543-554,I0004页

作者： A.Fernandez Francisca P.Araujo Y.Guerra s.Castro-Lopes J.Matilla-Arias Idglan s.de Lima eds.n C.silva-Filho Josy A.Osajima F.Guerrero R.Pena-Garcia Federal University of Piau Graduate Program in Materials Science and EngineeringTeresinaPIBrazil Federal Rural University of Pernambuco Academic Unit of Cabo de Santo AgostinhoCabo de Santo AgostinhoPEBrazil Federal University of Piaui Department of PhysicTeresinaPBrazil Federal University of Pernambuco Graduate Program in Materials ScienceRecifePEBrazil University of Granma Departmentof Basic Sciences and Applied InformaticsFaculty of Technical SciencesBayamoCuba Federal University of Amazonas Department of PhysicManausAMBrazil Federal University of Pernambuco Department of PhysicRecifePEBrazil

Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy(eds) spectra and textural properties show corallike structures, peaks associated with Pr^(3+) and Yb^(3+) atoms and the effect of dopants on surface area,diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12)compound. The saturation magnetization(M_(s)), cubic anisotropy constant(K_(1)) and coercive field(H_(c)) increase with the Pr^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr^(3+)and Yb^(3+)and it is shown that, relatively high dosages of Pr^(3+) cations favored the activity against s. aureus, therefore, a new biological property for YIG doped with rare earths is presented.

关键词： Yttrium iron garnet(YIG) Coral-like structures Rare earths Band gap energy Magnetic properties Antimicrobial properties

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基于氯化胆碱的低共熔体系在Au上电沉积无枝晶Zn

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Transactions of nonferrous Metals society of China 2024年第7期34卷 2367-2380页

作者： Vesna s.CVETKOVIĆ nebojša D.nIKOLIĆ Tanja s.BARUDŽIJA silvana B.DIMITRIJEVIĆ Jovan n.JOVIĆEVIĆ Department of Electrochemistry Institute of ChemistryTechnology and MetallurgyUniversity of BelgradeNjegoševa 1211000 BelgradeSerbia Institute for nuclear sciences Vinča University of BelgradeP.O.Box 52211001 BelgradeSerbia Mining and Metallurgy Institute Zeleni bulevar 3519210 BorSerbia

以氯化胆碱和乙二醇混合液为低共熔溶剂,不使用其他添加剂,电化学沉积无枝晶Zn/Au合金。在不同的Zn(Ⅱ)浓度下,采用恒电位电沉积法在相对较低的Zn电沉积过电位下进行电沉积。通过循环伏安法(CV)和计时安培法(CA)揭示Zn电沉积的电化学机... 详细信息

以氯化胆碱和乙二醇混合液为低共熔溶剂,不使用其他添加剂,电化学沉积无枝晶Zn/Au合金。在不同的Zn(Ⅱ)浓度下,采用恒电位电沉积法在相对较低的Zn电沉积过电位下进行电沉积。通过循环伏安法(CV)和计时安培法(CA)揭示Zn电沉积的电化学机理。采用扫描电子显微镜和X射线衍射分析(XRD)对沉积层的形貌和结构进行表征,并用能谱仪对沉积层进行元素分析。CV结果表明,Zn的电沉积始于Zn欠电位沉积区,并一直持续到Zn过电位沉积(OPD)区。随着Zn(Ⅱ)浓度的增加,Zn/Zn(Ⅱ)电偶的沉积电位向更高的正值偏移。CA分析表明,在Zn的OPD区开始三维渐进形核,随后形成三维生长。形貌分析表明,电沉积始于致密Zn岛的形成,随后形成无枝晶Zn/Au合金。XRD分析表明,其物相为金属Zn、立方AuZn3和Au Zn金属间化合物。

关键词：锌电沉积低共熔溶剂锌金合金形貌结构

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source of metals related to gold occurrences in Cameroon, Central African Belt

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Acta Geochimica 2024年第2期43卷 308-324页

作者： Kevin Igor Azeuda ndonfack Jinlin Zhang Yuling Xie nsamiratou Yaya Emmanuel Archelaus Afanga Basua JCHX Mining Management Co. LtdBeijing 101500People’s Republic of China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037People’s Republic of China school of Civil and Environmental Engineering University of Science and Technology BeijingBeijing 100083People’s Republic of China Department of Earth science University of BamendaBamendaRepublic of Cameroon

suites of granitic and metamorphic rocks form a perfect geological environment in which to investigate the source of metals related to gold *** the East Province of Cameroon,the source of metals-related gold(grade~4.6 g/t)that occurs within metamorphic and granitic rocks remains *** host rocks were subjected to XRF and ICP-Ms whole-rock geochemistry and BsE/eds mineral analyses to investigate the source(s)of metals related to gold in the ***,chalcopyrite-pyrite and magnetite-ilmenite are the main sulfi des and oxides of granites,*** low-grade metamorphic rocks are sulfi de-rich consisting of ars.nopyrite,chalcopyrite,pyrite,and sphalerite,and oxides include magnetite,ilmenite,hematite,and ***,ni,Co,sb,sc,and Zn concentrations depleted in high-grade metamorphic rocks and granites compared to low-grade metamorphic *** well,Bi,Cd,Co,Cu,ni,sb,V,W,and Zn concentrations decrease with increasing temperatures from low-grade rocks to high-grade rocks and *** suite of depleted elements in high-grade rocks and granites is almost identical to those enriched in gold *** conclude that metals(Bi,Cd,Co,Cu,ni,sb,and Zn)related to gold mineralization in the East Province of Cameroon likely originated from metal-rich low-grade metamorphic rocks during prograde metamorphic processes prior to partial melting.

关键词： East Province of Cameroon Metamorphic rocks Granites Oxide–sulﬁdes Metal and gold Geochemistry

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synthesis of spherical Y_(2)O_(3):Er emitting particles with variable radial composition by controlled double-jet precipitation of layered precursors

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Particuology 2023年第3期74卷 92-102页

作者： Danil K.Aleshin Maxim A.Mashkovtsev Anastasiya s.Kosykh Yulia A.Kuznetsova Anatoly F.Zatsepin Vladimir n.Rychkov Institute of Physics and Technology Ural Federal University19 Mira Str.620002YekaterinburgRussia

spherical(Y_(0.98)Er_(0.02))_(2)(OH)_(5)(nO_(3))·xH_(2)O particles were synthesized by controlled double-jet precipitation,with a“core”of pure layered yttrium hydroxide nitrate,and a“shell”of co-precipitated yttrium-erbium layered hydroxide *** an increase in precipitation pH from 7 to 9.5,the size of layered“building units”decreases and the architecture of their assemblies changes from flower-like through network-like spherical to irregular *** there,spherical particles gradually increase their diameter due to the continuous uniform growth of curved layered sheets on their *** was established that such growth behavior and network-like architecture of spherical particles was retained even when yttrium was replaced by erbium ions in the layered host lattice during the formation of an Er-enriched“shell”.Analysis of sEM,eds,XPs,photoluminescence spectra and concentration quenching effects of heat-treated Y_(2)O_(3):Er(2 at.%)particles indicate that the radial distribution of erbium in particles is most controllable in a narrow pH range of co-precipitation of layered precursors(pH8).Вy widely varying the elemental composition of“building units”during co-precipitation,one can simultaneously finely control the composition of layered hydroxides in the radial direction of the spherical particles and grow multicomponent“multi-shell”powders with desired properties.

关键词： Layered hydroxides Erbium Controlled precipitation Emitting particles Photoluminescence Concentration quenching

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TiO_(2)/WO_(3)heterogeneous structures prepared by electrospinning and sintering steps:Characterization and analysis of the impedance variation to humidity

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Journal of Advanced Ceramics 2019年第2期8卷 238-246页

作者： Evando s.ARAuJO Victor n.s.LEAO Research Group on Electrospinning and nanotechnology Applications(GPEA-nano) Department of Materials ScienceUniversidade Federal do Vale do Sao Francisco

Relative humidity(RH) is a critical environmental variable for transportation and storage of products and for the quality guarantee of several other production processes and services. Heterogeneous structures prepared from the selective semiconductor oxides may improve the sensitivity to humidity due to the better electronic and surface properties, when compared to pristine oxides. This work shows an alternative fabrication route for producing titanium dioxide/tungsten trioxide(TiO2/WO3) heterogeneous structures(by electrospinning and sintering) for potential application on the RH detection. The microstructural properties of the materials were analyzed by scanning electron microscopy(sEM), energy dispersive X-ray analysis(eds), X-ray diffraction, and Raman spectroscopy. The electrical characterization of the structures was performed by electrical impedance spectroscopy in RH range of 10%–100%. Results indicated a p-to n-type conduction transition at around 30%–40% RH for all tested settings. The analysis of the impedance signature to humidity showed that the amount of fiber layers on the electrode and working temperature are important parameters to improve the humidity sensing of the TiO2/WO3 systems.

关键词： electrospinning heterogeneous structures preparation relative humidity semiconductors

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Effect of B_(4)C on strength coefficient,cold deformation and work hardening exponent characteristics of Mg composites

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Journal of Magnesium and Alloys 2022年第5期10卷 1381-1400页

作者： s.suresh M.navaneetha Krishnan s.C.Vettivel Department of Mechanical Engineering University College of EngineeringNagercoilTamilnaduIndiaPin:629004 Department of Mechanical Engineering Universal College of Engineering and TechnologyVallioorTamilnaduIndiaPin:627117 Department of Mechanical Engineering Chandigarh College of Engineering and TechnologyChandiagarh 160019India

The emphasis of this exploration was to examine the workability and work hardening performance of Mg(Magnesium)specimen and Mg-B_(4)C composites created via the powder metallurgy *** pure Mg and Mg-B_(4)C composites are made with distinct weight percentages(Mg-5%B_(4)C,Mg-10%B_(4)C,and Mg-15%B_(4)C)at the unit aspect *** powders and composites characterization are executed by sEM(scanning Electron Microscope),eds(Energy Dispersive spectrum)with an elemental map,and XRD(X-ray Diffraction)*** displays that,the B_(4)C particles were dispersed consistently with the Mg *** workability and work hardening examination was conducted in triaxial stress conditions using the cold deformation *** consequence of workability stress exponent factor(β_(σ)),distinct stress proportion factors(σ_(m)/σ_(eff)and σ_(θ)/σ_(eff)),instantaneous work hardening exponent(n_(1)),work hardening exponent(n),coefficient of strength(k)and instantaneous coefficient of strength(k_(1))are *** outcome displays that Mg-15%B_(4)C specimen has greater workability and work hardening parameter,initial relative density,and triaxial stresses compared with the Mg specimen and Mg-(5–10%)B_(4)C composites.

关键词： Powder metallurgy Cold deformation Workability Instantaneous work hardening exponent Workability stress exponent Triaxial stress

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Influence of ZrO_(2)/siO_(2) nanomaterial incorporation on the properties of PEO layers on Mg-Mn-Ce alloy

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Journal of Magnesium and Alloys 2022年第2期10卷 552-566页

作者： D.V.Mashtalyar I.M.Imshinetskiy K.V.nadaraia A.s.Gnedenkov s.L.sinebryukhov A.Yu.Ustinov A.V.samokhin s.V.Gnedenkov Institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok 690022Russian Federation Far Eastern Federal University Vladivostok 690922Russian Federation A.A.Baikov Institute of Metallurgy and Materials science Russian Academy of SciencesMoscow 119991Russian Federation

The properties of coatings formed on the MA8 magnesium alloy by the plasma electrolytic oxidation in electrolytes containing mechanical mixture of zirconia and silica nanoparticles in concentrations of 2,4 and 6 g/l have been *** has been established by sEM,eds,and XPs that ZrO_(2)/siO_(2)nanoparticles successfully were incorporated into the ***-Raman spectroscopy showed the presence of ZrO_(2)in tetragonal and monoclinic forms in the PEO-coating composition as well as Mg_(2)siO_(4) in tetrahedral configuration uniformly distributed in the outer part of *** coatings significantly reduce corrosion current density in comparison with bare Mg alloy and base PEOlayer(from 2.4×10^(–7)A/cm^(2) for base PEO layer to 0.7×10^(–7)A/cm^(2) for coatings with nanoparticles).It has been found that the presence of solid nanoparticles in the composition of coating has a positive effect on their hardness(this parameter was increased from 2.1±0.3 GPa to 3.1±0.4 GPa)and wearproof(the wear was reduced from(4.3±0.4)×10^(–5)mm^(3)/(n×m)to(3.5±0.2)×10^(–5)mm^(3)/(n×m)).

关键词： Plasma electrolytic oxidation Composite coatings nanoparticles Zirconia silica Protective coatings

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