查看更多>>摘要：NH3-SCR is an effective mean of NOx removal in the non-electric industry,however,the high activation temperature and poor H2O resistance of SCR catalysts posed a barrier to its application.In this work,a series of three-dimensionally ordered macroporous(3DOM)catalysts were synthesized via a colloidal crystal template(CCT)method,and various characterizations were carried out to explore the physico-chemical property of catalysts.The experiment results reveal that Ce0.2Mn0.2/3DOM-TiO2 catalyst pre-sents the excellent low-temperature catalytic activity of nearly 100％at 100 ℃.Furthermore,the enhanced H2O resistance is achieved,certified by the unaffected NO remove at 150 ℃ in the participation of 15 vol％H2O.The characterizations results exhibit that the improved dispersion of the active component and enhanced redox ability are conducive to the low-temperature catalytic activity.N2 adsorption and desorption experiments indicate that catalyst with 3DOM support possesses a larger pore diameter and specific surface area,which may weaken the condensation of H2O in the microporosity of catalysts and improved the H2O resistance of the catalyst.In situ DRIFTS results manifest that Ce0.2Mn0.2/3DOM-TiO2 catalyst could not only absorb more NH3 and generate more surface-active sites,but inhibit the competitive adsorption between H2O and SCR reactants.
查看更多>>摘要：Excellent magnetic properties in ferrites are required for high-frequency applications and for wastewater treatment.Thus,the present study shows the comparison of magnetic and structural properties of Nd and Sm substituted Ni-Zn-Bi ferrites with the series Ni0.5Zn0.5Bi0.04NdxFe1.96-xO4(with step size 0.002)and Ni0.5Zn0.5Bi0.04SmxFe1.96-xO4(with step size 0.02)prepared using citrate precursor method.The impact of the substitution of rare earth ions(Nd and Sm)on magnetic properties of the synthesized samples is observed using a vibrating sample magnetometer(VSM).The saturation magnetization values enhance considerably from 52 to 58 emu/g for Nd3+ions and 39 to 57 emu/g for Sm3+ions,thus,making these materials magnetically hard.Further,the higher value of coercivity is also observed ranging from 133 to 167 Oe for Nd3+ions and 81 to 155 Oe for Sm3+ions.The shape of hysteresis loops indicates a super paramagnetic and ferromagnetic behavior in the obtained samples.The squareness ratio value is＜0.5,suggesting the uniaxial anisotropy of particles and hence,these ferrites are suitable for microwave-absorbing and in permanent magnetic materials.The X-ray diffraction(XRD)pattern shows the for-mation of pure cubic crystallites,where,lattice parameters range from 0.840 to 0.839 nm and from 0.838 to 0.839 nm for Nd3+and Sm3+ions substitution,respectively.The crystallite size ranges between 28.63 to 29.89 nm and 18.33 to 26.23 nm,for substitution of Nd3+and Sm3+ions,respectively.Field emission scanning electron microscopy(FESEM)shows the formation of homogeneous grains,whereas,energy dispersive spectrometer(EDS)counts describe the purity of the samples.The Sm concentration x=0.10 has the maximum surface area with value of 42.6 m2/g which proves to be having good data storage application due to high surface area.The zero-field cooled(ZFC)and field cooled(FC)data show that Nd-doped Ni-Zn-Bi nanoferrites show superparamagnetic behaviour in the room temperature range which makes them suitable for practical applications.
查看更多>>摘要：Coral-like structures of the Y3-xPrxFe5-yYbyO12,(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-Iond angle,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 coral-like structures,peaks associated with Pr3+and Yb3+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 Y3-xPrxFe5-yYbyO12 compound.The saturation magnetization(Ms),cubic anisotropy constant(K1)and coercive field(Hc)increase with the Pr3+cations content,as consequence of their magnetic nature and distribution around of Fe3+ions due to the coexistence with the Yb3+.Finally,for the first time,antibacterial tests by mean of the direct contact method were per-formed for YIG co-doped with Pr3+and Yb3+and it is shown that,relatively high dosages of Pr3+cations favored the activity against S.aureus,therefore,a new biological property for YIG doped with rare earths is presented.
查看更多>>摘要：Combinations of metal and lanthanide oxides have been done through casted films for potential medical applications.In this regard,samarium(Ⅲ)oxide/chromium(Ⅲ)oxide/graphene oxide(GO)/poly-caprolactone(PCL)based films nano-composites(NCs)were fabricated,pointing their utilization as a biological scaffold for wound dressing purposes.Also,samarium(Ⅲ)oxide and chromium(Ⅲ)oxide have been merged as promising optical constituents due to their unique optical behavior.The structural and compositional examination of the studied NCs was executed by X-ray diffraction(XRD),Raman,and field emission scanning electron microscopy(FESEM).The Sm2O3/Cr2O3/GO/PCL NC exhibits a surface with a lower roughness degree owing to the presence of GO.Cr2O3 shows size reduction upon GO insertion to reach 1.2 μm as the average grain size,whilst Sm2O3 records an average grain size of less than 1 μm.As well,the polymeric nano-compositions exhibit variation in contact angle values that hit 29.76°±3.52° for Sm2O3/PCL,and 48.62°±1.37° for Sm2O3/Cr2O3/GO/PCL as the second lowest contact angle.The optical behavior contributes to absorption edge relocation along the x-axis from 1.7 eV for pure PCL,to 2.65 eV for Sm2O3/Cr2O3/GO/PCL.Regarding biological responses,the cell exposed to 2.5 μg/mL of Sm2O3/Cr2O3/GO/PCL shows cell viability of 119.31％,while 5 μg/mL hits 99.6％.Additionally,the resulting cell attachment micrographs show layers of fibroblast tissue,besides the proliferation and growth of culti-vated cells.Thus,the Sm2O3/Cr2O3/GO/PCL scaffold provides 3D proliferation of fibroblast cells endorsing the wound healing process.
查看更多>>摘要：Computational calculations using density functional theory(DFT)were performed for the first time using the full potential linearized augmented plane wave plus local orbital method(FP-LAPW+LO)to determine the structural,elastic,electronic and magnetic properties of europium-based cubic perov-skites EuYO3(Y=Cr,Mn,Fe).The exchange correlation potentials of GGA along with some analytical methods were adopted for the computation of structural and elastic properties.Moreover,the GGA+U formalism was also added for obtaining more precise electronic and magnetic properties,particularly to address the Eu-4f and Y-3d orientations in the spin-polarized double cell symmetry.The observed lattice parameters of these compounds are consistent with experiment.The observed bulk moduli predict that EuCrO3 is harder and less compressible than EuMnO3 and EuFeO3.The calculated tolerance factors of these compounds are within the cubic symmetry range.Our computed critical radius of EuCrO3 shows that EuCrO3 has a larger migration energy.Based on their elastic properties,these compounds are ductile in nature.We also computed the thermal properties of these compounds.The band structures and density of states show that these compounds are metallic in character.The lowest ground state energy and magnetic moments of these compounds expose their ferromagnetic nature.The metallic nature and strong ferromagnetism of these compounds make them promising applicants for application in spintronic.
查看更多>>摘要：The research of poly(ethylene oxide)(PEO)-based solid composite electrolyte with high ionic conduc-tivity and excellent interfacial stability is the key to the development of all-solid-state lithium-ion bat-teries(ASSLIBs).Herein,uniform nanorod structured CeO2 fillers were controllably synthesized by electrospinning,which were subsequently filled into PEO polymer to prepare CeO2/PEO solid composite electrolyte.The addition of CeO2 nanorods can reduce both the glass transition temperature and the melting point of PEO polymer,and also interact with PEO and lithium bis(trifluoromethanesulphonyl)imide(LITFSI)by Lewis acid-base reaction.Therefore,the solid composite electrolyte exhibits a high ionic conductivity of 4.52 x 10-4 S/cm,a wide electrochemical stability window of about 4.8 V,and a good interfacial stability with Li at 55 ℃.Moreover,the LiFePO4/Li ASSLIB divulges the discharging specific capacity of 165,162,156 and 146 mA·h/g at 0.2,0.5,1 and 2 C,respectively,and achieves the capacity retention of 90.3％after 150 cycles at 0.5 C.Consequently,one dimensional CeO2 nanorods can be considered as an alternative filler for polymeric solid electrolyte.
查看更多>>摘要：The present research investigated the effect of reduced graphene oxide(rGO)integration with as-synthesized Er2O3/ZnO nanocomposites on dielectric properties.The samples were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM),diffuse reflectance spectroscopy(DRS),and energy dispersive spectroscopy(EDS).Complex impedance spectroscopy was utilized to characterize dielectric relaxation phenomena in Er2O3/ZnO and Er2O3/ZnO/rGO nanocomposites.All the samples exhibit single relaxation phenomena which are ascribed to grain boundaries.The addition of rGO to Er2O3/ZnO nanocomposite results in the enhancement of dielectric response due to increased local field intensity caused by the formation of conducting-insulating interfaces.Furthermore,the AC conductivity of the Er2O3/ZnO/rGO is increased at higher frequencies due to the presence of free charge carriers in rGO.At higher frequencies,Er2O3/ZnO/rGO nanocomposite with increased concentration of ZnO exhibits a more stable dielectric constant with extremely low dielectric loss.Hence,the inclusion of rGO in Er2O3/ZnO nanocomposites makes it a novel prospective candidate in the field of energy storage devices.
查看更多>>摘要：The effects of Y2O3 on the microstructure,microhardness,wear resistance,high-temperature oxidation resistance,hot corrosion resistance,and electrochemical corrosion behaviour of CoCrFeNiTiNb high entropy alloy coatings formed on Ti-6Al-4V alloy surfaces were studied.The results show that the addition of Y2O3 changes the proportion of the phase but does not change its type.The average grain size is only 1/4.7 of that of the high entropy alloy(HEA)coating,and the fine-grained strengthening leads to increases in the microhardness and wear resistance of 21.8％and 26.9％,respectively.The addition of Y2O3 enhances the denseness and bonding properties of the oxide and corrosion product layers,reducing the oxidation and hot corrosion rates by 60.3％and 40.3％,respectively.The addition of Y2O3 doubles the corrosion resistance which is attributed to the refinement of the grains,the increased proportion of HCP and TiN,and the weakening of galvanic coupling corrosion.
查看更多>>摘要：To develop pure aluminum alloys with high conductivity and strength,Al-0.2Ce and Al-0.2Ce-0.1Y alloys were prepared by rolling and annealing processes in this study.The effects of trace rare earth elements on the strength and electrical conductivity of the pure aluminum alloys were investigated.It is revealed that the addition of Ce and Y to pure aluminum can effectively enhance the strength and electrical conductivity of the alloys.In Al-0.2Ce,the addition of Ce can effectively refine the grain size of α-Al,with an average grain size of 90.68 μm in the as-cast state.The grain size of the alloy is further reduced to 87.55 μm by the simultaneous addition of Y.The synergistic addition of Ce and Y changes the properties of the alloy.The addition of Ce and Y also produces the Al11Ce3 and Al3Y second phases,which have coherent relationship with α-Al.The two-dimensional mismatch degree was calculated to be only 4.43％and 0.85％,respectively,which can provide a certain amount of nucleation substrate for α-Al in the in-cubation stage.The interfacial match between the L12 structure of Al3Y and α-Al was calculated using first-principles simulations.The results indicate that Al3Y has a strong bonding effect with α-Al.Nano-scale second phases at grain boundaries can be effective in reducing resistivity due to dislocation motion.Nanoscale second phases with better matching interfaces to the substrate have no positive effect on the scattering motion of electrons.
查看更多>>摘要：In this study,the in-situ synthesized ZrB2 nanoparticles and rare earth Sc were introduced to enhance the strength and ductility of 7N01 aluminum alloy,via the generation of high-melting and uniform nano-dispersoids.The microstructure and mechanical property evolution of the prepared composites and the interaction between ZrB2 and Sc were studied in detail.The microstructure investigation shows that the introduction of rare earth scandium(Sc)can promote the distribution of ZrB2 nanoparticles,by improving their wettability to the Al melt.Meanwhile,the addition of rare earth Sc also modifies the coarse AlZnMgMnFe precipitated phases,refines the matrix grains and generates high-melting Al3(Sc,Zr)/Al3Sc nanodispersoids.Tensile tests of the composites show that with the combinatorial introduction of ZrB2 and Sc,the strength and ductility of the composites are improved simultaneously compared with the corresponding 7N01 alloy,ZrB2/7N01 composite and Sc/7N01 alloy.And the optimum contents of ZrB2 and Sc are 3 wt％and 0.2 wt％in this study.The yield strength,ultimate strength and elongation of(3 wt％ZrB2+0.2 wt％Sc)/7N01 composite are 477 MPa,506 MPa and 9.8％,increased about 18.1％,12.2％and 38％compared to 7N01 alloy.Furthermore,the cooperation strengthening mechanisms of ZrB2 and Sc are also discussed.
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