查看更多>>摘要：Cerium oxide(CeO2),or ceria,and its doped derivatives have been extensively studied for several de-cades and are well-known oxides valued for their unique structural properties and wide range of ap-plications.These materials play a crucial role in sustainable development within society.Structural modification through defect engineering of the highly stable cubic fluorite phase enhances the versatility of this doped ceria to a new level.Among the numerous dopants of the CeO2 matrix,ceria doped with gadolinium(Gd),known as Ce1-xGdxO2-∂(CGO),is gaining popularity due to its multifunctionality.The introduction of defect-induced vacancies in the oxygen sublattice(Vo)and a change in the average valence of cerium(Ce3+/Ce4+)are primarily responsible for the improved performance compared to pristine CeO2.These materials are currently undergoing intensive research for potential use as electro-lytes in intermediate-temperature solid oxide fuel cells(IT-SOFCs)and dense oxygen-permeable mem-branes(OPMs).Additionally,they are being commercially utilized for power generation and oxygen separation.CGO materials are also attracting significant attention in various fields such as optics,pho-tocatalysis,electrostriction,spintronics,gas sensing,electrocatalysis,and biomedical applications.This review paper aims to compile the latest contributions to CGO materials and comprehensively cover their various application areas.The crystal structure,defect equilibrium in Gd3+-doped CeO2,the origin of multifunctionality,and the prospects of these materials are also exclusively discussed.
查看更多>>摘要：The envisaged design and development of individual materials to excavate a broader spectrum of desired properties and offer multiple applications are highly necessitating.Keeping this in mind,a series of forsterite-structured Mg2GeO4:Eu3+(1 mol％-9 mol％)nanophosphors was synthesized via a solution combustion method using oxalyl dihydrazide as a fuel.The X-ray diffraction patterns confirm the orthorhombic crystal system with a Pnma space group.Morphological results clearly show irregularly shaped cluster-like structures with aggregation of the particles.Employing diffuse reflectance spectra,the optical energy band gap of the Mg2GeO4:Eu3+(1 mol％-9 mol％)nanophosphors was estimated and obtained to be～4.12-4.32 eV.The photoluminescence emission spectra exhibit intense peaks at～579,589,610,661,and 707 nm,which are due to characteristic 5D0 → 7F0,5D0 → 7F1,5D0 → 7F2,5D0 → 7F3 and 5D0 → 7F4 transitions of Eu3+ions,respectively.The Commission International de L'Eclairage color coordinates are gradually tuned from pale red(0.5980,0.4012)to a pure red(0.6385,0.3611)region.Thermoluminescence glow peaks showcase excellent super-linear response at low doses of γ-irradia-tions,indicating that the prepared phosphor can be used in thermoluminescent personal dosimetry which is a biological tissue equivalent.The aforementioned results demonstrate that the prepared Mg2GeO4:Eu3+(1 mol％-9 mol％)nanophosphors are considered an excellent candidate for dual appli-cations,i.e.,red component in future generation white-light-emitting diodes(WLEDs)and personal dosimetric applications.
查看更多>>摘要：The rapid development of phosphor-converted white light emitting diodes(pc-WLEDs)requires new red phosphors with efficient and thermally stable luminescence for high-quality warm-white lighting.However,it is still a challenge to discover red phosphors with facile synthesis,high internal quantum efficiency(IQE),excellent thermal stability and high color purity.Herein,a novel red-emitting Eu3+activated barium dialuminum digermanate(BaAl2Ge2O8,BAGO)phosphor showing strong red emission at 610 nm was prepared.The IQE is improved from 32.91％to 78.84％by employing a charge compen-sation strategy.The lithium-ion co-doped BAGO:Eu3+phosphor exhibits a nearly twofold increase in integral photoluminescence(PL)intensity and the high color purity reaches 94.17％.Impressively,the PL intensity of the BAGO:Eu3+,Li+phosphor drops by only 2.6％at 150 ℃ of that at room temperature.Finally,the pc-WLED using the red BAGO:Eu3+,Li+phosphor exhibits white light with the chromaticity coordinate of(0.3515,0.3495),a high color-rendering index of 92 and a low correlated color temperature of 4746 K.All these results manifest that BAGO:Eu3+,Li+phosphor is a suitable red phosphor for near-ultraviolet(NUV)chip-based pc-WLEDs.
查看更多>>摘要：The work focuses on the utilization of the conventional solid-state sintering procedure to synthesize white phosphors Ca2InTaO6:xDy3+(0.02≤x≤0.12).Utilizing X-ray diffraction,the phase structure of samples was examined,and the crystal structure was refined using the Rietveld method.A scanning electron microscope was used to analyze the microstructure of sample.First-principles calculations confirm that the indirect bandgap of Ca2InTaO6 is 3.786 eV.The luminous properties and energy transfer mechanism of Ca2InTaO6:xDy3+were studied using photoluminescence spectroscopy.The 4F9/2 → 6H13/2 transition of Dy3+ions is responsible for the greatest emission peak,which was measured at 575 nm.According to research,the lifespan falls as the concentration of Dy3+doping amount rises because of frequent interaction and energy transfer between Dy3+ions.The correlated color temperature of the W-LEDs packaged with Ca2InTaO6:0.08Dy3+is 4677 K and CIE 1931 chromaticity coordinates are(0.3578,0.3831).Meantime,the phosphor also shows outstanding temperature stability property,which main-tains 83.8％of its initial emission intensity at 450 K(activation energy of 0.1467 eV).The W-LEDs retain their performance for 100 min when powered at 3.4 V voltage and 600 mA current,demonstrating the packed W-LEDs'sustained operation at high temperatures.
查看更多>>摘要：In this study,a series of Mn-Ce/Al2O3 catalysts was prepared by different methods of deposition-precipitation(MnCeAl-DP),impregnation(MnCeAl-IM)and citric acid(MnCeAl-CA),and the distinct effect of preparation methods on NOx removal performance at low temperature was explored.Results show that MnCeAl-DP exhibits not only the best activity but also the highest resistance against SO2/H2O.With the assistance of comprehensive characterizations from scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),H2-temperature programmed reduction(H2-TPR),NH3-temperature programmed desorption(NH3-TPD),and X-ray photoelectron spectroscopy(XPS),it is revealed that the MnCeAl-DP sample owns admired features of large surface area and pore volume,enriched Mn4+and chemisorbed oxygen species originating from enhanced interaction between MnOx and CeO2,as well as improved adsorption capacity to NH3 and NO.All these factors contribute to activity enhancement.Further in-situ DRIFTS studies reveal that the improvement of NH3-SCR performance over MnCeAl-DP is related to the formation of abundant nitrate species,which is beneficial to the"NH4NO3"reaction pathway and thus enhances low-temperature activity.
查看更多>>摘要：Soil remediation containing numerous organic contaminants is of great significance to ecological envi-ronment.Herein,the synergetic effects of Ce-Mn/Al2O3 with different active components on catalytic thermal desorption of chlorobenzene in soil were investigated.The optimized Ce-Mn/Al2O3 drastically enhance the desorption efficiency of chlorobenzene,and the corresponding conversion reaches 100％within 1 h at a low temperature of 120 ℃.The superior performance is ascribed to the formation of Ce-Mn solid solution during the calcination process,resulting in a certain lattice change to the gener-ation of abundant oxygen vacancies and acidic sites.Combining with the analysis of in-situ diffuse reflectance infrared spectroscopy and gas chromatography-mass spectrometry,the final products of chlorobenzene are decomposed into CO2,H2O,Cl2 and HCl.This work sheds light on the rational design of highly-active catalysts for practical applications of sustainable soil remediation.
查看更多>>摘要：Due to its large magnetocrystalline anisotropy field and high Curie temperature,SmCo-based magnets are irreplaceable in high-temperature applications.The hot-deformed SmCo-based magnets are espe-cially attractive for their excellent corrosion resistance,making them more suitable for harsh environ-ments.However,it is still challenging for hot-deformed SmCo-based magnets to obtain high magnetization and high coercivity simultaneously.Therefore,it is necessary to analyze the relationship between its microstructure and magnetic properties and explore its magnetic hardening mechanism to guide the further improvement of magnetic properties.In this paper,the anisotropic heterostructure SmC05 magnet was prepared by combining large height-reduction and introducing a nano-grained Sm-rich phase.Strong c-axis texture,(BH)m of 16.1 MGOe,and Hci of 9.6 kOe were obtained via the heter-ostructure with SmCo5 micron-grain and Sm-rich nano-scale precipitates.The magnetic domain obser-vation and technical magnetization analysis demonstrate that the coercivity mechanism is dominated by nucleation.The results also show that the smooth and Sm-rich precipitated grain boundary provides weak pinning effects.It provides a reference for the development of high-performance nanocrystalline SmCo5 magnets.
查看更多>>摘要：In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu7-type SmFex(x＞9)by the low-temperature diffusion-reduction(LTRD)process using LiCl-KCl eutectic molten salts.Firstly,the Sm-Fe phase transformation depending on the Sm-Fe composition,the LTRD temperature,and time was investigated,and it is found that the obtained metastable phase is only TbCu7-type SmFe～8.5,which is not a Fe-rich phase.This Fe content does not change even after an expended LTRD process,and the metastable TbCu7-type SmFe～8.5 tends to transform to the stable Sm2Fe17 phase.In addition,it is found that the Sm-Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe2,SmFe3,and SmFe8.5 as the LTRD temperature increases(when the time was 10 h)or the LTRD time increases(when the temperature was 550 ℃).Core-shell-like particles are observed in the case of a short LTRD time,and the core and the shell are Fe and the Sm-rich Sm-Fe phase,respectively,indicating that the Sm-rich phase begins to produce on the surface of the Fe particles.It is difficult to synthesize a Fe-rich TbCu7-type SmFex(x＞9)phase with the Sm-Fe binary system,suggesting that a different approach,such as addition of other elements,will be necessary.
查看更多>>摘要：The tumor microenvironment(TME)differs from normal tissue cells in its physiological and biochemical characteristics.The construction of TME-responsive nanoplatforms requires a tedious preparation pro-cess and complex multicomponent modification.In this work,Er@EGCG-Cu,a TME-responsive nano-platform,was simply and rapidly synthesized by combining rare earth-doped nanomaterials(NaLuF4:Yb,Er)with EGCG-Cu which is based on the ability of metal ions to coordinate with polyphenols to form a metal-phenolic network(MPN)structure.The MPN structure is then destroyed under an acidic TME,releasing the chemotherapy(CT)drug EGCG,which can cause apoptosis.CuxSy is generated by combining Cu2+with H2S overexpressed in human colorectal cancer cells and can be used for photo-thermal therapy(PTT).Cell experiments show that laser irradiation improves the CT/PTT synergistic effect of Er@EGCG-Cu.This study has significance for the construction of TME-responsive nanomedicines with simple and rapid preparation for synergistic therapy.
Ahmed H.IbrahimYehia M.AbbasH.A.AyoubMarwa H.Ali...
1903-1911页
查看更多>>摘要：Herein,we report the synthesis of a Dy-Gd co-doped cubic phase-stabilized Bi2O3 solid electrolyte system via solid-state processing under atmospheric conditions.Doping with Dy3+and Gd3+has been observed to significantly enhance the densification process during sintering for stabilization purposes,thereby improving the electrical properties of δ-Bi2O3-type polymorphs.The synthesized ceramics were characterized using X-ray diffraction(XRD),field emission scanning electron microscopy-energy dispersive X-ray spectroscopy(FESEM-EDX),thermal gravimetry/differential thermal analysis(TG/DTA),and the four-point probe technique(4PPT).XRD analysis reveals that the samples Bi1-x-yGdxDyyO1.5(y=0.05/x=0.05,0.10,0.15,and 0.20,and x=0.05/y=0.10,0.15,and 0.20)exhibit a stable face-centered cubic δ-phase and a mixed-phase crystallographic structure.The XRD analysis of the stabilized δ-phase suggests that the prepared oxides show a face-centered cubic(FCC)structure with a space group of Fm-3m.FESEM micrographs reveal that the composition Bi0.90Gd0.05Dy0.05O1.5 has no significant holes.Nevertheless,an evident increase in the pore formation is observed as the amount of Gd2O3 increases until it reaches 20％.This finding suggests that dense pellets are formed during the sintering process at 900-1000 ℃.The DTA analyses were performed to verify the phase stability,which agrees with the XRD results.The electrochemical performance of the synthesized Dy-Gd co-doped Bi2O3 solid electrolyte system was evaluated and analyzed in detail by using the electrochemical impedance spectroscopy(EIS)technique.Based on EIS and conductivity measurements,Bi0.75Gd0.20Dy0.05O1.5 ex-hibits the lowest activation energy of 0.519 eV and the highest conductivity value of 0.398 S/cm at 627 ℃ compared to the other samples;this composition can be used as a solid electrolyte for intermediate-temperature solid oxide fuel cells(SOFCs).
NETL
NSTL
万方数据