A novel visible-light Nd-doped CdTe photocatalyst for degradation of Reactive Red 43：Synthesis,characterization, and photocatalytic properties

Novel high-efficiency visible-light-sensitive Nd-doped Cd Te nanoparticles were prepared with various doping concentrations of neodymium ion by a facile hydrothermal method. The reaction products were analyzed via X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), photoelectron spectroscopy(XPS), and UV-Vis diffuse reflectance spectroscopy techniques. Red shift was seen in the absorption band edge peak in the UV-Vis absorbance spectrum with increasing Nd content. The XRD and XPS results confirmed that Nd ions successfully replaced Cd atoms and were incorporated into the crystal lattice of Cd Te. SEM and TEM images indicated spherical structure and high crystallinity. Even at a very low Nd/Cd Te molar ratio of 2 mol.%, Nd doping could greatly enhance the photocatalytic activity of Cd Te. The photocatalytic activity of Nd-doped Cd Te nanoparticles was evaluated by monitoring the decolorization of RRed 43 in aqueous solution under visible-light irradiation. The color removal efficiency of Nd0.08Cd0.92 Te and pure Cd Te were 83.14% and 14.32% after 100 min of treatment, respectively. Among different amounts of the doping agent, 8 mol.% Nd indicated the highest decolorization. The presence of radical scavengers such as Cl-, CO32-, SO42-, and buthanol was found to reduce the decolorization efficiency.     

Ultraviolet to near-infrared energy transfer in NaYF_4:Nd~(3+),Yb~(3+) crystals

To convert ultraviolet(UV) light into near-infrared(NIR) light in phosphors is demanded for the development of solar cells.A series of NaYF_4:Nd~(3+),Yb~(3+) white powder samples were prepared via the hydrothermal method.The crystal structure and photoluminescence properties of the samples were carefully studied using X-ray diffractometry(XRD) and photoluminescence spectra.The excitation and emission spectra of NaYF_4:Nd~(3+),Yb~(3+) samples and the luminescence decay curves of Nd~(3+) and Yb~(3+) revealed an efficient energy transfer process from Nd~(3+) to Yb~(3+).This process resulted in the Yb~(3+) NIR fluorescent emission at 980 nm.Moreover,the lifetime of the Nd~(3+4)F_(3/2) level decreased with the increase of Yb~(3+) doping concentration.The build-up time of the decay curves of the Yb~(3+2)F_(5/2) level further verified the energy transfer process.Meanwhile,energy transfer efficiency based on different Yb~(3+) doping concentrations was achieved.     

Preparation of cerium and yttrium doped ZnO nanoparticles and tracking their structural,optical,and photocatalytic performances

Yttrium(Y) and cerium(Ce) co-doped ZnO nanoparticles(NPs) were synthesized via the simple sol-gel auto-combustion route.The effect of Ce and Y doping on the structure,morphology,optical,Zeta potential,and photocatalytic activities of ZnO NPs was examined by Fourier transform infrared(FTIR)spectrometer,X-ray diffraction(XRD),transmission electron microscope(TEM),UV-vis spectrophotometer,and Zetasizer instrument.XRD data show that the fabricated samples crystallize into a hexagonal wurtzite struct...     

Preparation and application of ZnO doped Pt-CeO2 nanofibers as electrocatalyst for methanol electro-oxidation

ZnO doped Pt/CeO₂ nanocomposites were prepared by electrospinning and reduction impregnation. X-ray diffraction (XRD), transmission electron microscopy (TEM), energy disperse spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the nanocomposites. It is observed that ZnO and CeO₂ form the hexagonal wurtzite phase and cubic fluorite phase in the nanocomposite, respectively, whilst Pt nanoparticles (NPs) with the number-averaged size of ca. 3.1 nm are uniformly distributed on the surface of nanofibers. The mass fraction of Pt NPs in the nanocomposites is about 10 wt%. The doping of ZnO is effective to promote reactive oxygen species, surface reaction sites and the interaction between Pt and oxides. The catalytic performance of nanocomposites was evaluated by the methanol electro-oxidation, indexed with the catalytic activity, stability of catalyst. As a result, it is found that the nanocomposite exhibits much higher activity and stability for methanol oxidation than the undoped Pt/CeO₂ catalyst.     

Presence of neodymium and gadolinium in cobalt ferrite lattice:Structural,magnetic and microwave features for electromagnetic wave absorbing

In this work,neodymium substituted gadolinium-cobalt ferrite nanoparticles were synthesized by hydrothermal method.The significant role of doping both the Nd~(3+)and Gd~(3+) ions to cobalt ferrite in manipulating the cation distribution and further in influencing structural and magnetic properties was experimentally studied and reported.The influence of Nd~(3+) substitution was investigated with step of 0.02-0.1 into the optimized Gd-Co compound.The crystal structure formation and crystallite size were explored by X-ray diffraction analysis in which the crystallite size and lattice constant decrease with increasing the Nd~(3+) substitution.The microstructural properties were studied by field emission scanning electron microscopy and atomic force microscopy studies.The obtained structural and morphological results reveal that the substitution of Nd~(3+) with more than 0.06 into the Gd-Co ferrites will change the material be havior and trends.The saturation magnetization and coercivity values were measured using a vibration sample magnetometer at room temperature.Comparative microwave absorption experiments demonstrate that the reflection loss properties enhance with increasing substitution of Nd~(3+) cations in Gd-Co ferrite spinel structure.This research reports that the as-prepared Nd~(3+) substituted Gd-Co ferrite compound stands as promising candidate for absorbing electromagnetic wave with a wider absorbing bandwidth of X-band.     

Recent progress of energy transfer and luminescence intensity boosting mechanism in Nd~(3+)-sensitized upconversion nanoparticles

Rare earth doped upconversion nanoparticles can be considered as the spice of research in the field of luminescence nanomaterials due to their unique optical properties such as near-infrared excitation.Enormous works have been reported about biomedical applications of 980 nm excited and Yb~(3+)-sensitized upconversion nanoparticles.However,980 nm excitation wavelength overlaps with the absorption band of water molecules in the biological environment,leading to overheating effect that can induce thermal damages of normal cells and tissues.Recently,Nd~(3+)-sensitized upconversion nanoparticles which can be excited with 808 nm has been widely investigated as alternative nanoparticles that can surmount this issue of overheating effect.Even though Nd~(3+)-sensitized upconversion nanoparticles can reduce the overheating effect by 20 fold as compared to Yb~(3+)-sensitized counterpart,there are several factors that reduce the upconversion luminescence intensity.In this review article,photon energy harvesting and transferring mechanisms in Nd~(3+),Yb~(3+)and emitter ions co-doped upconversion nanoparticles under 808 nm excitation are briefly discussed.Factors that affect upconversion luminescence intensity and quantum yield of Nd~(3+)-sensitized upconversion nanoparticles are also addressed.Besides,some of the important strategies that have been recently utilized to boost upconversion luminescence intensity of Nd~(3+)sensitized upco nversion nanoparticles are tho roughly summarized.Lastly,the future challenges in the area and our perspectives are in sight.     

Structural characterization and optical properties of long-lasting CaAl_2O_4:Eu~(2+),Nd~(3+) phosphors synthesized by microwave-assisted chemical co-precipitation

The present paper reported the structural and luminescent properties of Eu~(2+) and Nd~(3+) doped CaAl_2O_4 phosphor. The samples were prepared by microwave-assisted chemical co-precipitation(MA-CCP), a synthesis technique which is suitable for small and uniform particle that could be used directly without grinding. The effects of different microwave temperatures on structure and photoluminescence behavior were studied. Formation of a phosphor and phase purity were confirmed by X-ray diffraction technique(XRD) with variable microwave temperatures. XRD analysis showed that the phosphors prepared by MA-CCP method at the temperature of 750, 900oC, respectively and solid-state reaction(SSR) method at 1300oC consisted of impurities. Commission Internationale de L'Eclairage(CIE) color coordinates of CaAl_2O_4:Eu~(2+),Nd~(3+) were suitable as blue light emitting phosphor. Excitation and emission peaks of the samples prepared by different methods in this study were almost the same. The images of SEM showed that the size of the phosphors prepared by MA-CCP method reached a submicrometer.     

Improved luminescence and photocatalytic properties of Sm3+-doped ZnO nanoparticles via modified sol-gel route:A unified experimental and DFT+U approach

In the current study,a modified sol-gel route was used to produce undoped and Sm³⁺ doped(1 mol%,3 mol% and 5 mol%) ZnO nanoparticles(NPs).The study of opto-structural properties of Sm³⁺ doped NPs was carried out both experimentally and theoretically.Complete dissolution of Sm³⁺ ions into the ZnO lattice is obviously seen from X-ray diffraction(XRD) analysis.Morphological evolution with doping was studied using field emission scanning electron microscopy(FESEM) an...     

氧化钕电解的阴极过程及钕的溶解行为

本文用循环伏安法和重差法分别测定了 NdF_3-LiF-CaF_2熔体中氧化钕电解的阴极过程;金属钕在该熔体中的溶解损失;在120～300安培级电解槽中进行了氧化钕电解试验,并将所得的电解指标与氯化钕电解法进行了对比分析。     

Fabrication and properties of La modified AZO powders via a gaseous penetration processing

A new kind of AZO powders were synthesized by co-precipitation method with the doping content of Al was 3.0 wt%. Further modification of La to the powders was done via a gaseous penetration processing. Changes in constitution,structure,and electrical conductivity caused by doping and penetration were characterized. The doping of Al lowered the resistivity of AZO powders from over 1×1014(ZnO made domestically) to 4.24×107 Ω·cm. But more effective modification via gaseous penetration processing decreased the resistivity of La penetrated AZO powders to the lowest point of 2.45×105 Ω·cm. The optimal penetration conditions coordinated by orthogonal test were that La3+ content of the penetration solvent was 2.0 wt.%,and that the penetration processing lasted for 5 h at the temperature of 480 oC. XRD analysis demonstrated that the doping process of Al only leaded to the changes of the peak width and intensity without new phases appearing. Yet,new phases appeared after the processing of gaseous penetration of La,which indicated that La enter the AZO powders thus complex reactions occurred to form the extra compounds. EDAX analysis,coupling with XRD,provided the evidence that La did exist in the penetrated AZO powders and the potential sign of the generation of extra compounds. Through SEM images,it was illustrated that the gaseous penetration processing progressed the growth of grain size in the shape of rod and generated distinguishable phases of extra compounds.     

Sensitizing effect of Nd~(3+) on Tb~(3+) activated ZrP_2O_7 long persistent phosphor materials

The long persistent phosphors of Zr_(0.97)P_2 O_7:0.018 Tb~(3+),0.012 Nd3+with Nd~(3+)as sensitized ions and Tb~(3+)as emission centers were synthesized using high temperature solid state reaction.The crystal structure and defects,excitation and emission spectra,decay curves and thermoluminescence(TL) curves of the phosphors were investigated.The synthesized Zr_(0.97)P_2 O_7:0.018 Tb3+,0.012 Nd3+is essentially in line with the standard card PDF#49-1079.The emission band with main peak at 548 nm exhibits the characteristic transitions of ~5 D_3-~7 F_j(j=5,4) and ~5 D3-~7 F_j(j=6,5,4,3) of Tb~(3+).The analysis of excitation and emission spectra shows that there exists the overlap between the emission peaks of Nd~(3+)at 466 and 485 nm and the excitation of Tb3+at 443 and 485 nm,and the energy transfer from Nd3+to Tb3+plays an important role in the improvement of luminescence properties.The decay curves shows that Zr_(0.97)P_2 O_7:0.018 Tb3+,0.012 Nd3+has longer afterglow time than ZrP_2 O_7 and Zr_(0.982)P_2 O_7:0.018 Tb3+.Additionally,the TL curves indicate that the trap depth at 0.72 eV in Zr_(0.97)P_2 O_7:0.018 Tb~(3+),0.012 Nd3+is to the benefit of the afterglow time.The possible luminescence mechanism of ZrP_2 O_7:Tb~(3+),Nd3+is proposed on the basis of the XPS spectra,EPR spectra,excitation and emission spectra,decay curves,TL curves and the analysis of defect equations.     

Spectroscopic properties and energy transfer of Nd3+/Ho3+-doped Ga2O3-GeO2 glass by codoping Yb3+ ion

This study presented the luminescence properties of Nd³⁺/Yb³⁺/Ho³⁺ dopant ions inside a host based on Ga₂O₃-GeO₂-Li₂O（GGL） glass. The measured differential scanning calorimetry result showed that GGL glass exhibited excellent stability against devitrification with ?T=135 oC. Obvious 543 and 657 nm emissions were observed in Nd³⁺/Ho³⁺-codoped sample. The incorporation of Yb³⁺ into Nd³⁺/Ho³⁺-codoped glass system had resulted in enhanced upconversion emission intensity under the excitation of 808 nm and/or 980 nm laser diode（LD）. The possible mechanisms and related discussions on this phenomenon were presented. It was noted that the presence of Yb³⁺ yielded an enhancement about 7 and 11 times in the 543 and 657 nm emission intensities respectively under 808 nm excitation due to the energy transfer from Nd³⁺ to Ho³⁺ via Yb³⁺ ion. Here Yb³⁺ played a major role as a bridging ion. While enhanced 543 and 657 nm emission intensities under the excitation of 980 nm LD originated from the sensitization effect of Yb³⁺. Our results showed that Nd³⁺/Ho³⁺/Yb³⁺ triply doped GGL glass might be a promising candidate for the development of visible-laser materials.     

Synthesis and characterization of rare earth metal doped tungsten trioxide photocatalyst for degradation of Rhodamine B dye

Nowadays,it is concern for researchers that due to high recombination rate of photogenerated charge carriers in tungsten trioxide(WO₃) nanoparticles,the future applications are limited in the field of photocatalysis.Herein we attempt to synthesize tungsten trioxide nanoparticles with different doping concentrations of lanthanum i.e.2 wt%,4 wt%,6 wt% and 8 wt%.The synthesized samples were characterized by using various characterization techniques:X-ray diffraction(XRD),Raman spectrosco...     

Enhancement of terbium efficiency by gallium and copper co-doping in (Pr,Nd)-Fe-B sintered magnets

It is well known that Tb substitution for (Pr, Nd) in (Pr, Nd)-Fe-B based sintered magnetic materials is an effective way to increase intrinsic coercivity, but it is not quite clear whether the increment depends on the different matrix phases with various doping ingredient or not, which is essential to develop high quality magnets with high coercivity more efficiently and effectively with economic consumption of expensive Tb and other costly heavy rare earths. In this paper, we investigated the efficiency of Tb substitution for magnetic property in (Pr, Nd)-Fe-B sintered permanent magnets by co-doping Ga and Cu elements. It is shown that Ga and Cu co-doping can effectively improve the efficiency of Tb substitution to increase the thermal stability and the coercivity. The intrinsic coercivity increases up to 549 and 987 kA/m respectively by 1.5 wt% and 3.0 wt% Tb substitution in Ga and Cu co-doped magnets while the intrinsic coercivity increases up to only 334 and 613 kA/m respectively by the same amounts of Tb substitution in non-Ga and low-Cu magnets. In other words, it demonstrates that there is about 329–366 kA/m linear equivalent enhancement of intrinsic coercivity by 1.0 wt% Tb substitution for (Pr, Nd) in Ga and Cu co-doped magnets. The temperature coefficients of both intrinsic coercivity β and remanence α at 20–150 °C by 3.0 wt% Tb substitution for the magnets with Ga and Cu co-doping are −0.47%/K and −0.109%/K respectively, and in contrast those values are −0.52%/K and −0.116%/K respectively for the non-Ga and low-Cu magnets. It is the principal reason for more efficient enhancement of magnetic property by Tb substitution in the Ga and Cu co-doped magnets in which Tb atoms are expelled from triple junction phases (TJPs) to penetrate into the grain boundary phases (GB phases) and thus modify the grain boundary. It is prospected that the efficiency of Tb substitution would rely on different matrix phases with various doping constituents.     

Fabrication and properties of La modified AZO powders via a gaseous penetration processing

A new kind of AZO powders were synthesized by co-precipitation method with the doping content of Al was 3.0 wt%. Further modification of La to the powders was done via a gaseous penetration processing. Changes in constitution, structure, and electrical conductivity caused by doping and penetration were characterized. The doping of Al lowered the resistivity of AZO powders from over 1×10¹⁴ (ZnO made domestically) to 4.24×10⁷ Ω·cm. But more effective modification via gaseous penetration processing decreased the resistivity of La penetrated AZO powders to the lowest point of 2.45×10⁵ Ω·cm. The optimal penetration conditions coordinated by orthogonal test were that La³⁺ content of the penetration solvent was 2.0 wt.%, and that the penetration processing lasted for 5 h at the temperature of 480 °C. XRD analysis demonstrated that the doping process of Al only leaded to the changes of the peak width and intensity without new phases appearing. Yet, new phases appeared after the processing of gaseous penetration of La, which indicated that La enter the AZO powders thus complex reactions occurred to form the extra compounds. EDAX analysis, coupling with XRD, provided the evidence that La did exist in the penetrated AZO powders and the potential sign of the generation of extra compounds. Through SEM images, it was illustrated that the gaseous penetration processing progressed the growth of grain size in the shape of rod and generated distinguishable phases of extra compounds.     

Effect of RE~(3+) electronegativities on luminescence property of Ba_5Si_8O_(21):Eu~(2+) persistent phosphor

A series of Ba_5Si_8O_(21):0.02Eu~(2+),0.09RE~(3+) persistent phosphors were synthesized by the solid-state reaction method.The measurement results of photoluminescence(PL),phosphorescence and thermoluminescence(TL)were analysed and discussed.The XRD results showed that samples codoped with different RE~(3+) were Ba_5Si_8O_(21) single pure phase.Under the excitation,all samples exhibited a broad Eu~(2+) characteristic emission,and the La~(3+) co-doped sample emitted the brightest photoluminescence even though its persistent luminescence property was the worst because of the weakest electronegativity.However,Nd~(3+) electronegativity was suitable,thus after activation,the Ba_5Si_8O_(21):Eu~(2+),Nd~(3+) sample had the best persistent luminescence performance with the highest phosphorescence intensity and the persistent luminescence decay time beyond 8 h.The Nd~(3+) co-doped sample also had the largest thermoluminescence integral area which proved effectively it had longer persistent luminescence time.The luminescence mechanism was also proposed to study the photoluminescence and persistent luminescence process.These results showed that RE~(3+) electronegativities were distinctly important for persistent phosphors and choosing suitable electronegativity codopant was conducive to enhancing the phosphorescent performance.     

Photoluminescence properties of LaF3：Eu^3＋ nanoparticles prepared by refluxing method

The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), UV-vis diffuse reflectance spectrum, and photoluminescence spectra. The results of XRD indicated that the obtained LaF3: Eu3+ nanoparticles were well crystallized with a hexagonal structure. The FE-SEM image illustrated that the LaF3: Eu3+ nanoparticles were spherical with an average size around 30 nm. Under irradiation of UV light, the emission spectrum of LaF3: Eu3+ nanoparticles exhibited the characteristic line emissions arising from the 5D0→7FJ (J=1, 2, 3, 4) transitions of the Eu3+ ions, with the dominating emission centered at 590 nm. In addition, the emissions from the 5D1 level could be clearly observed due to the low phonon energies (-350 cm-1) of LaF3 matrix. The optimum doping concentration for LaF3: Eu3+ nanoparticles was determined to be 20mol.%.     

Effects of grain boundary ternary alloy doping on corrosion resistance of(Ce,Pr,Nd)-Fe-B permanent magnets

To satisfy the application of different environments,grain boundary doping is commonly used in the preparation of sintered magnets to improve the coercivity and the corrosion resistance.In this paper,the alloys were prepared by mixing different ratios of the master alloy(Ce,Pr,Nd)-Fe-B and the sintering aid(Pr,Nd)-Al.The coercivity of sintered(Ce,Pr,Nd)-Fe-B magnet is substantially enhanced by doping 2 wt%of(Pr,Nd)-Al,while the maximum energy product decreases slightly.We systematically investigated the corrosion behavior and micro structure of the sintered magnets in order to determine the mechanism of the degradation.The sintered(Ce,Pr,Nd)-Fe-B magnets with 2 wt% of(Pr,Nd)-Al addition exhibit the decreasing corrosion rate compared with others,due to the distribution of intergranular phases.The electrode potential difference between the main phase and the RE-rich phase is reduced by the addition of Al,improving the potential and stability of RE-rich phase due to the higher electrode potential of Al than that of Nd,Pr or Ce.In addition,the element distribution of the magnets doped by(Pr,Nd)-Al indicates that the Al-rich shell formed at the marginal area of the Ce-rich phase improves its stability.Therefo re,intergranular adding te rnary(Pr,Nd)-Al alloy powders results in both high coe rcivity and good corrosion resistance synchronously.     

Enhanced visible-light photocatalytic activity of samarium-doped zinc oxide nanostructures

In the present work,we have synthesized samarium doped zinc oxide nanostructures(Zn_(1-x)Sm_xO;x=0.00,0.02,0.04 and 0.06) via chemical precipitation method and studied their structural,morphological,optical and photocatalytic properties.X-ray diffraction(XRD) patterns,PL and Raman spectra results indicate that the undoped and Sm-doped ZnO nanostructures are crystallized in a hexagonal wurtzite structure.FESEM images show that the morphology of the sample changes from cubical to hexagonal nanostructures with increase in Sm~(3+)doping concentration.The EDX spectra confirm the incorporation of Sm~(3+)ion in ZnO.The influence of Sm~(3+)doping on the structure,morphology,absorption,emission and photocatalytic activity of ZnO nanostructures were investigated systematically.The addition of Sm~(3+)ion leads to a red shift in the optical energy band gap from 3.19 to 2.67 eV and hence,increases the visible light absorption ability.The presence of E_2(H) and E_1(LO) modes in microRaman spectra confirms the crystallinity and defects in the samples.The detailed photocatalytic experiments reveal that Sm-doped ZnO nanostructures show the maximum photodegradation efficiency for Methylene blue(MB) dye for x=0.04,i,e.,94.94%,under visible light irradiation.The photocatalytic efficiency improves by 6.98 times when ZnO is doped with rare earth metal ion(Sm~(3+)) and is a potential candidate for practical applications.The investigation demonstrates that as-synthesized nano-sized photocatalysts act as an efficient photocatalyst for the degradation of MB dye.     

Influence of Doping Rare Earth on Performance of Lithium Manganese Oxide Spinels as Cathode Materials for Lithium-Ion Batteries

The cathode material plays an important role inthe performance of lithium ion batteries. Commerciallithium cells use lithium cobalt oxide cathodes and thehigh cost of this material has prompted the design andsynthesis of alternate insertion hosts. Among these al ternatives, spinel LiMn2O4 has been found to bepromising in terms of specific energy, non toxicity,and low cost[1~3]. It is thought that lithium man ganese oxides will be used in lithium ion batteries forel…