Mechanism of Phase Transformation and Formation of Barium Hexafer rite Doped with Rare-Earths in Sol-Gel Process

The phase-transformation in sol-gel preparation of barium hexaferrite and the formation of barium hexaferrite doped with La 3+ were studied by chemical p hase analysis, X-ray diffraction and infrared spectrometry analysis. The expe rimental results show that phase transformation reactions of FeCO 3, Fe 2O 3 and BaFe 2O 4, barium hexaferrite and γ-Fe 2O 3 take place in the heat tr eatment of gel. While the doping lanthanide ion replace barium ion, an equivalen t quantity of Fe 3+ are reduced to Fe 2+ to maintain the charge equili brium.

Anti-UV Capability of Rare Earth Doping TiO_2

The sol-gel process is used in the preparation of nanostructure materials with Ti(OC_ 4 H_ 9 )_ 4 as precursor in the start materials. TiO_ 2 gelatin is obtained through hydrolysis and condensation process. Rare earth such as La_ 2 O_ 3 , CeO_ 2 , Eu_ 2 O_ 3 and Gd_ 2 O_ 3 are introduced into the nanostructure TiO_ 2 to improve the anti-UV capacity. The phase structure of pure TiO_ 2 and doped TiO_ 2 and their anti-UV capacity are studied by means of XRD and UPF. The optimum doping and heat treatment temperature are chosen.

Specific mode output from multimode fiber oscillators by designing rare earth doping profiles

Based on rate equations, a theoretical model of a fiber oscillator with a multimode gain fiber was built. We studied the effect of the rare earth doping profile in the core on the output characteristics of the multimode fiber oscillator. The results indicated that a pure fundamental mode can be obtained by partly doping the core of the large mode area （LMA） ytterbium doped fiber （YDF） in the fiber laser. Furthermore, a sole specific high-order mode can also be implemented by tailoring the rare earth doping profile according to the simulations. The mode coupling effect was also taken into account in the model. In spite of the mode coupling effect, the specific mode was able to dominate in the output of the fiber laser by utilizing the designed LMA YDF.

Rare Earth Ion Yb^3+ Doping of Bi2WO6 with Excellent Visible-light Photocatalytic Activity

The rare earth ion Yb^3+ doped Bi2WO6 photocatalysts were synthesized by hydrothermal method.Moreover,XRD,XPS,FESEM,TEM,Ramam,N2 adsorption-desorption isotherm measurements and UV-vis diffusion reflectance spectra were used to characterize the Yb^3+ doped Bi2WO6 photocatalysts.The morphology,specific surface area,and pore volume distribution were greatly affected after Yb3+ ions doping.Photocatalytic performance of Bi2WO6 was effectively enhanced after Yb3+ ions doping,6% Yb^3+ doped Bi2WO6 had the best photocatalytic performance,and 96.2% Rhodamine B was degradated after irradiated 30 min,which was 1.29 times that of the pristine one.The enhanced photocatalytic performance was due to the increased specific surface area,decreased energy band gap and inhibition of photoelectron-hole recombination after Yb3+ ions doping.

Effects of Rare Earth Doping on the Properties of γ-Fe_2O_3 Magnetic Powder

The effects of rare earth doping on the formation process of α-FeOOH crystallite and the properties of γ-Fe2O3 magnetic powder were investigated. The growth of needle α FeOOH crystallite was completed by the basic process. The experimental results show that the rare earth doping can increase the aspect axial ratio of needle α-FeOOH grains. its anti-sintering capability during the heat-treatment and the thermostability of γ-Fe2O3 magnetic properties. The magnetic properties of γ-Fe2O3 doping with rare earth are as follows: the coercivity Hc=36.3 kA/m (445 Oe), the ratio saturation magnetization σs=90.4μWbm/kg (72 emu/g), the ratio remanent magnetization σr=54 μWbm/kg (43 emu/g), and the temperature coefficient of remanent magnetization of γ-Fe2O3 doping with 0.1 mol% Dy can reach -5 ×10-4℃-1.

Effect of doping elements on catalytic performance of CeO_2-ZrO_2 solid solutions

CeZr, CeYZr, LaCeZr, LaCePrZr, LaCePrYZr, and LaCePr solid solutions were prepared via the coprecipitation method, and characterized by means of X-Ray Diffraction （XRD） and Brunauer-Emmett-Teller （BET） techniques. The oxygen storage capacity （OSC） of the solid solutions was evaluated by the pulse technique and the catalytic activity was assessed using a 4-channel catalysis device. It was seen that the solid solutions presented cubic structure. The specific surface area and thermal stability could be enhanced by doping Y into the solid solutions. Doping a small amount of La had a positive effect on the thermal durability while doping a large amount of La decreased the specific surface area and the thermal stability. LaCePrZr and LaCePrYZr solid solutions synthesized using Baotou rare earth mineral residue enriched with LaCePr after Nd extraction presented a certain higher value in specific surface area and thermal stability, thereby enabling to be used as economic catalysts for automobile exhaust purification. Coating Al2O3 or SiO2 layer on the surface of ceria-zirconia solid solutions increased the specific surface area and thermal resistance.

Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....

Inhomogeneity of Rare Earth Doped Ⅲ-Ⅴ Compounds Grown by LPE

The processing of InP, GaAs and related compounds doped with rare earth metals, such as Er, Nd and Gd, grown by LPE is described. The inhomogeneity of rare earth heavily doped epi-layers is studied by SIMS, SEM and X-ray diffraction techniques.

Synthesis and Characterization of Titania and Rare Earth Doped Titania Nanoparticles by Sol-gel Process

Titania sol has been prepared by the sol-gel process with Ti（OC4H9）4, as precursor. TiO2 gel was obtained through hydrolysis and condensation process. Rare earth such as La2O3, CeO2 and Gd2O3 were introduced into the nanostructure TiO2. After TiO2 and rare earth doped TiO2 powders were calcined at 400℃, 500℃, 600℃, 700℃ and 800℃ respectively, the characteristic analyses of the TiO2 samples were studied by UV-VIS, XRD and TEM etc. It was found that there are some stringer absorption peaks at 200 - 325 nm. The rare earth doping can increase the phase transition temperature convertin8 anatase phase into rutile phase, can decrease the grain size of TiO2particles and can improve the ann-UV capacity of the coating fabrics.

Effect of rare earth Nd^(3+)doping contents on physical,structural,and magnetic properties of Co-Ni spinel ferrite nanoparticles

Rare earth(RE)low doping has a significant influence on the structural,morphological,and magnetic properties of spinel ferrite nanoparticles.Therefore,rare earth neodymium(Nd)oxide was fully doped into spinel ferrite with a composition of Co_(0.80)Ni_(0.20)Nd_xFe_(2-x)O_4(x=0.0,0.05,0.10,and 0.15)using the sol-gel auto combustion method.Structural analysis of the synthesized samples with low doping of Nd using X-ray diffraction(XRD)and Rietveld refinements reveals a pure single-phase cubic structure,while the second phase appears with increasing content of Nd^(3+)at x=0.10 and 0.15.Scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HR-TEM)show well-shaped spherical grains within the nanometer range of the pure Co_(0.80)Ni_(0.20)Fe_(2)O_(4) sample,while larger grains with the presence of agglomeration are observed with doping of Nd^(3+)into the spinel ferrite nanoparticles.The magnetic parameters,i.e.,saturation magnetization M_s,remanence and magnetic moments exhibit decreasing trend with Nd^(3+)doping and M_s values are in 65.69 to 53.34 emu/g range.The coercivity of the Nd-doped Co-Ni spinel ferrite sample was calculated to be 1037.76 to~827.24 Oe.This work demonstrates remarkable improvements in the structural and magnetic characteristics of Nddoped Co-Ni spinel ferrite nanoparticles for multiple versatile applications.

Structural,optical,electrical,and dielectric relaxation properties of rare earth containing sodium bismuth titanate Na_(0.5)Bi_(0.5)TiO_(3) perovskite:Effect of ionic radius

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.5)B_(0.5)TiO_(3),NBT) based perovskite nanomaterials.The X-ray diffraction data indicate the successful formation of the rhombohedral phase(space group R3c) of NBT nano perovskite incorporated with various rare earth ions in Bi-site.The lattice parameters were found to increase linearly with the ionic radius of the dopant cation.The ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared compositions.The grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic radius.Field emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and stoichiometry.The UV-Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap,which unfolds the application of NBT-based perovskite as photoactive material.The ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius,i.e.,La-doped NBT compound,exhibits the highest dc and bulk conductivity with the lowest activation energy.The frequency-dependent dielectric data follows Havriliak-Negami(HN) formalism and non-Debye type relaxation phenomena.Results also indicate that La-doped NBT composition exhibits the highest dielectric strength value.Thus,this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural,optical,and electrical properties.

Structural,morphological,optical and antibacterial performances of rare earth(Sm)-doped ZnO nanorods

The significant rise of ultra-violet(UV) radiation and pathogenic infectious bacteria poses a serious threat to global health.Numerous researchers' interests are attracted by novel materials with strong UVblocking ability,antibacterial activity and low toxicity to other species.In this case,a simple wet chemical method with different annealing temperatures(400,500,and 600℃) was employed to create highly effective rare earth(Sm)-doped ZnO nanorods.The(101) plane of wurtzite ZnO shifts towards a lower angle with increasing annealing temperature,according to the X-ray diffraction(XRD) study findings,which additionally establishes the consequence of lattice expansion.Occurrence of doublet peaks of Sm 3d(Sm 3d_(5/2) and Sm 3d_(3/2)) in the X-ray photoelectron spectroscopy(XPS) spectrum clearly validates the substitution of Sm^(3+) ions in the 500℃-annealed samples.The 500℃-annealed nanorods exhibit combined performances of the wide band gap,improved UV absorbance,and vivid green luminescent emission(563 nm).Additio nally,the nanorods have favorable UV-blocking execution of 96% for UVA at 360 nm,92% for UVB at 320 nm,and 57% for UVC at 225 nm,which is greater than the majority of ZnO-related materials that have been reported up to this date.Sm doping is also appropriate for improving bacterial inhibition against the two studied strains(Escherichia coli and Staphylococcus aureus),in addition to the intriguing features discussed above.Furthermore,with maximum inhibition zone diameters of 20±0.72 and 18±0.57 mm,respectively,these nanorods exhibit high inhibitory action against E.coli and S.aureus bacterial strains.The rare earth-doped material developed during the current experiment,which was annealed at 500℃,could potentially serve as an effective replacement for UV-blocking and antibacterial material,especially for biomedical applications.

Mathematical Modelling of Einstein’s Rate Equations for Zinc Phosphate Glass with Er³⁺-Yb³⁺

There is a constant growth in the demand of data information transmission capacity, that is, more and more people send data, voice, video signals, among others, through communications networks. Due to the above there is great interest in improving network devices, such as optical amplifiers, which must cover a large bandwidth and generate greater gain than those currently available. For this reason in this work a computational simulation for a Quasi-system was carried out three energy levels of Erbium and Ytterbium varying their concentrations and proving that they are optimal candidates in a zinc phosphate matrix as this type of glass contains properties such as, high transparency, low melting point, high thermal stability, high gain density due to high solubility, low refractive index and low dispersion, which makes them optimal as signal amplifiers. The results confirm that by increasing the doping of the Erbium ion the gain of the amplifier decreases, contrary to the Ytterbium ion that by increasing the doping the gain of the amplifier increases.

Enhanced strain and electrostrictive properties in lead-free BNT-based ceramics via rare earth doping

Bi_(0.5)Na_(0.5)TiO_(3)(BNT)-based ceramics are one of the most promising lead-free ferroelectrics due to their high strain property.Compared to other chemical modifications,rare earth ions doping provides sig-nificant possibility to optimize the strain property of BNT-based ceramics.In this work,the effects of rare earth ions on phase structure,microstructure,and strain&electrostrictive properties of lead-free BNT-based ceramics were systematically investigated.Rare earth ions(i.e.,La^(3+),Sm^(3+),Yb^(3+),Dy^(3+),and Nd ^(3+))were selected as the doping ions.Introducing moderate La^(3+)ions can drive the ferroelectric state of BNT-based ceramics to nonergodic relaxor state or ergodic relaxor state.The enhanced strain response of~0.40-0.42% and high converse piezoelectric coefficient of~600-630 pm/V can be achieved under 60-70 kV/cm for La^(3+)-doped ceramic with nonergodic relaxor state.Besides,the giant electrostrictive coefficient Q 33 of~0.047 m 4/C 2 can be obtained for La ^(3+)-doped ceramic with ergodic relaxor state.Other rare earth ions also present the promotion effect on strain enhancement for BNT-based ceramics.This study affords a significant guidance to optimize strain and electrostrictive properties of BNT-based ce-ramics via rare earth ions doping.

A Review on Fiber Lasers

After a half century of development, fiber laser has evolved from a concept to a great family penetrating into various fields of applications. This paper reviews the history and current development of fiber lasers, with topics covering both continuous wave and short pulse fiber lasers. Important issues such as the major rare earth dopants, fiber laser brightness, polarization effects, clad pumping technology, beam combination, mode locking and pulse shaping are discussed in this paper.

Effect of rare earth ions doping on properties of LiFePO_4/C cathode material

LiFe0.99RE0.01PO4/C cathode material was synthesized by solid-state reaction method using FeC2O4-2H2O, Li2CO3, NH4H2PO4, RE（NO3）3·nH2O as raw materials and glucose as a carbon source. The doping effects of rare earth ions, such as La3＋, Ce3＋, Nd3＋, on the structure and electrochemical properties of LiFePO4/C cathode material were systematically investigated. The as-prepared samples were characterized by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM） and particle size analysis. The electrochemical properties were investigated in terms of constant-current charge/discharge cycling tests. The XRD results showed that the rare earth ions doping did not change the olivine structure of LiFePO4, and all the doped samples were of single-phase with high crystallinity. SEM and particle size analysis results showed that the doping of La3＋, Ce3＋ and Nds＋ led to the decrease of particle size. The electrochemical results exhibited that the doping of La3＋ and Ce3＋ could improve the high-rate capability of LiFePO4/C cathode material, among which, the material doped with 1% Ce3＋ exhibited the optimal electrochemical properties, whose specific discharge capacities could reach 128.9, 119.5 and 104.4 mAh/g at 1C, 2C and 5C rates, respectively.

Synthesis,structure and luminescence properties of KEu_(0.01)Gd_(0.19)Yb_(0.8)(WO_4)_2 powder

The synthesis of co-doped KEu0.01Gd0.19Yb0.8（WO4）2 was achieved by a modified Pechini method at 750℃. The structure of obtained compound was confirmed using X-ray diffraction measurement and Raman spectroscopy. The Scherrer＇s formula was used to confirm the grain sizes visualized by TEM technique. The grain sizes of about 100 nm of monoclinic KGW were successfully obtained by this meth- odology. In order to study spectroscopic properties of the prepared system the emission spectra were measured. The effective down- and up-conversion processes in non-resonant system were investigated.

Electro-catalytic degradation properties of Ti/SnO_2–Sb electrodes doped with different rare earths

Ti/SnO2–Sb electrode has a good effect on the removal of organic pollutants. But its short service life limits its large-scale application in industry. Electro-catalytic degradation performances and service life of the electrode can be significantly improved by doping rare earth（RE） ions into the oxide coating of Ti/SnO2–Sb electrode. Ti/SnO2–Sb electrodes doped with different RE elements（Ce, Dy, La, and Eu） were prepared by the thermal decomposition method at 550 ℃. Electro-catalytic degradation performances of electrodes doped with different RE elements were evaluated by linear sweep voltammetry（LSV） and Tafel curves. During the electrolysis,the conversion of p-nitrophenol was performed with these electrodes as anodes under galvanostatic control. The structures and morphologies of the surface coating of the electrodes were characterized by scanning electron microscope（SEM）. The results demonstrate that the electro-catalytic degradation performances of Ti/SnO2–Sb electrodes are improved to different levels by doping different RE ions. Improved Ti/SnO2–Sb electrodes by the introduction of different RE have higher oxygen evolution potential, better electro-catalysis ability, better coverage,and longer electrode life.

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(WO_(3)) 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 spectroscopy,Fourier transform infrared spectroscopy(FTIR),photoluminescence spectra(PL),transmission electron microscopy(TEM),energy dispersive X-ray(EDX) and UV-Vis spectroscopy.WO_(3) retains its monoclinic structure even after doping which was confirmed by XRD analysis.FTIR helps to descry functional groups present in the samples.The size of nanoparticles was calculated by using TEM.EDX confirms the absence of any impurity in the synthesized samples.Raman spectroscopy confirms the presence of a large number of imperfections induced in the lattice of WO_(3).The rate of recombination was analyzed by photoluminescence(PL) spectroscopy and is minimum in 4 wt% doping of lanthanum.The optical bandgap was calculated using UV-Vis spectroscopy and becomes narrow along with the doping concentrations.Intriguingly,it is found that doping of La in WO_(3) has considerably ameliorate the photocatalytic activity by reducing rate of recombination due to the trapping of electrons by defects introduced in the lattice.Photocatalytic decolorization of Rhodamine B(RhB) dye was performed and the values of c/c_0 and rate constant(k) confirm that the 4 wt% doping shows maximum degradation efficiency.The kinetic study for photodegradation of Rhodamine B was done by using various kinetic models and results show that the reaction follows first order kinetics very well.Therefore,optimum doping of lanthanum increases the decolorization ability of WO_(3) towards RhB dye.

Influence of La-dopant on the Material Characteristics and Supercapacitive Performance of MnO_2 Electrodes

Manganese dioxide was synthesized by electrodeposition method with Mn （CH3COO）24H2O as a raw material. La（NO3）3？6H2O was doped in electroyte during the preparing process to improve the performance of MnO2 electrodes. The micrographs, crystal structure and element content of electrodes were analyzed by SEM, XRD and atomic absorption spectroscopy, respectively. It is found that the La content ratio in the dioxide can be easily controlled by adjusting the composition of the plating solution. Appropriate amount of doped La can increase the surface area of Mn/La materials, resulting in the supercapacitive behavior enhancement. Electrochemical tests show that the specific capacitance is significantely increased from 198.72 F？g-1 to 276.60 F？g-1 by La-doping.