Amount Of Nd3 Research Articles

Controllably Modulating Oxygen Vacancies on Nonstoichiometric Nd−Ce−O Binary Oxides for Low‐temperature Oxidative Coupling of Methane

AbstractHerein, we synthesised a series of nonstoichiometric Nd−Ce−O composite oxides with a fluorite or rare‐earth C‐type phase structure using the glycine combustion method for the oxidative coupling of methane (OCM) reaction. As the amount of Nd3+ increases, the oxygen vacancies in this series of composite oxides gradually increase, leading to an amount increasing in the C2‐selective oxygen species O2− generated by the oxygen vacancies. In addition, with the increase in Nd3+, the number of moderate basic sites on the catalyst surface also improves, another significant factor affecting the OCM reaction performance of the composite oxides. Nd0.9Ce0.1O1.55 possesses optimal low‐temperature OCM reaction performance, achieving 8.0 % C2 yield at 450 °C and 14.1 % C2 yield at 700 °C. This can be attributed to the nonstoichiometric rare‐earth C‐type crystalline phase structure of Nd0.9Ce0.1O1.55, which exhibits the highest abundance of oxygen vacancies, selective oxygen species O2−, and moderate basic sites.

Investigation of radiation shielding and optical properties of neodymium doped Bismuth Boro tellurite glasses for solid state device applications

In this work, a variety of glass samples with different chemical profiles for optical applications were synthesized, and characterized. The thermal properties of the prepared glass are investigated through Differential Thermal Analysis (DTA) and we have observed the endothermic peak at 894.9 °C and exothermic peak at 1066 °C. The optical properties were investigated using a UV–Visible–NIR Spectrophotometer, and the radiation shielding properties were reported using the Phy-X/PDS software. The optical property results show that when the amount of Nd3+ ions in a glass structure grows, the oscillator strengths also increase. The high emission cross-section and excellent quantum efficiency indicate that glass has the potential for compact 1.06 μm laser applications. The Photoluminescence (PL) analysis of Nd3+ ions doped prepared glass samples are recorded at 808 nm laser diode. The emission spectra for every Nd3+ ion concentration exhibit three distinct emission peaks at wavelengths of 902 nm, 1064 nm, and 1339 nm. The investigation of luminescence kinetics revealed the development of neodymium ion clusters commencing at a neodymium concentration of 1.006 × 1020cm−3. Furthermore, we noticed that the addition of Nd2O3 increased the mass attenuation coefficient and effective atomic number of the glass samples. In terms of the glasses' ability to absorb charged particles, the Nd2O3 addition also made a difference in Half Value Layer, Mean Free Path, and Effective atomic number. The research shows that the glass samples are non-toxic, visible light transparent, and radiation-efficient.

Effect of the neodymium doping on the magnetic and structural properties of the Sr-hexaferrite obtained by the Pechini method

In this work, neodymium (Nd3+) doped strontium hexaferrite was obtained using the sol–gel based Pechini method. The cation distribution was modified by doping with different amounts of Nd3+ ions when 0.0 ? x ? 0.4 according to the chemical expression Sr1-xNdxFe12O19 the powders were sintered at 1100 °C for 1 h. The influence of the neodymium was analyzed, and the magnetic and structural properties have been associated with the fabrication method. The crystalline phases, structure, and particle morphology of the samples were determined by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. In addition, the magnetic properties were measured at room temperature using a vibrating sample magnetometer with an applied field of up to 20 kOe. Moreover, magnetization and coercivity values are influenced by the neodymium content. The results showed that the Pechini sol-gel method allows a limited solubility of the Nd3+ ions on the hexaferrite structure.

1.06 µm emission of Nd3+-doped aluminium barium lithium phosphate glasses for near IR laser medium material

Melt quenching was used to make aluminum barium lithium phosphate glasses doped with various amounts of Nd3+ ions. The absorption spectra of glasses showed twelve peaks and were increased with increasing of Nd2O3 concentrations. While the wavelength at 581 nm is the highest absorption. The emission spectra of Nd3+-doped glasses exhibited three dominant peaks at 901, 1066 and 1334 nm under exciting wavelength at 581 nm, it was related to the 4F3/2→4I9/2, 4I11/2 and 4I13/2 transitions, respectively. The wavelength at 1066 nm was observed that is the highest emission intensity. Because of the concentration quenching effect, the emission intensities accreted regarding concentration up to 1.0 mol%. After that, when it was higher than 1 mol%, the intensity decreased. The Ω2,Ω4andΩ6 were done by applying Judd-Ofelt theory to the absorption and emission results, which led to the calculation of the radiative transition probability and the stimulated emission cross-section. The JO parameters show Ω6>Ω2>Ω4 trend, it indicated more viscosity and rigidity of glasses. Glasses have had their stimulated emission cross-section determined. The results showed that Nd3+-doped aluminium barium lithium phosphate glass with a 1066 nm emission might be used as a near-infrared laser medium material.

Nd3+-Doped TiO2 Nanoparticles as Nanothermometer: High Sensitivity in Temperature Evaluation inside Biological Windows.

TiO2 nanoparticles doped with different amounts of Nd3+ (0.5, 1, and 3 wt.%) were synthetized by the sol–gel method, and evaluated as potential temperature nanoprobes using the fluorescence intensity ratio between thermal-sensitive radiative transitions of the Nd3+. XRD characterization identified the anatase phase in all the doped samples. The morphology of the nanoparticles was observed with SEM, TEM and HRTEM microscopies. The relative amount of Nd3+ in TiO2 was obtained by EDXS, and the oxidation state of titanium and neodymium was investigated via XPS and NEXAFS, respectively. Nd3+ was present in all the samples, unlike titanium, where besides Ti4+, a significantly amount of Ti3+ was observed; the relative concentration of Ti3+ increased as the amount of Nd3+ in the TiO2 nanoparticles increased. The photoluminescence of the synthetized nanoparticles was investigated, with excitation wavelengths of 350, 514 and 600 nm. The emission intensity of the broad band that was associated with the presence of defects in the TiO2, increased when the concentration of Nd3+ was increased. Using 600 nm for excitation, the 4F7/2→4I9/2, 4F5/2→4I9/2 and 4F3/2→4I9/2 transitions of Nd3+ ions, centered at 760 nm, 821 nm, and 880 nm, respectively, were observed. Finally, the effect of temperature in the photoluminescence intensity of the synthetized nanoparticles was investigated, with an excitation wavelength of 600 nm. The spectra were collected in the 288–348 K range. For increasing temperatures, the emission intensity of the 4F7/2→4I9/2 and 4F5/2→4I9/2 transitions increased significantly, in contrast to the 4F3/2→4I9/2 transition, in which the intensity emission decreased. The fluorescence intensity ratio between the transitions and were used to calculate the relative sensitivity of the sensors. The relative sensitivity was near 3% K−1 for and near 1% K−1 for .

Synergistic upconversion photodynamic and photothermal therapy under cold near-infrared excitation

Lanthanide-doped upconversion nanoparticles (UCNPs) have been extensively investigated due to their unique capabilities of upconverting near-infrared light (NIR) to visible/ultraviolet emission. However, use of conventional Yb-based UCNPs under 980 nm excitation for biomedical applications is limited due to the overheating caused by the strong light absorption by water at this wavelength. Although this could be improved by using Nd3+-Yb3+ codoped UCNPs and changing the excitation wavelength to 808 nm, the amount of Nd3+ doping is usually below 20 mol% due to the lattice strain in highly Nd-doped core–shell structures. In this study, we report Nd3+-sensitized NaYF4:Yb,Er@NaLuF4:Nd@NaLuF4 UCNPs, in which the NaLuF4 in the intermediate shell can accommodate more structural changes caused by the Nd3+ doping, and allow for high concentration of Nd3+ doping (up to 50 mol%). Due to such high Nd3+ doping in the nanostructure, the red and green upconversion emissions of as-synthesized UCNPs are significantly increased upon 808 nm excitation, which are used to activate two photosensitizer drugs, MC540 (merocyanine 540) and FePc (iron phthalocyanine), for the dual photodynamic and photothermal therapy. The results show that the generation of reactive oxygen species (ROS) upon 808 nm light excitation is substantially boosted due to the synergistic therapeutic effect, which significantly prohibits the growth of cancer cells. It is believed that the nanoplatform specially developed in this study can solve the overheating issue associated with the 980 nm light excitation and the combined photodynamic and photothermal therapy can significantly improve the cancer therapy efficacy.

Enhancement in Curie Temperature of Yttrium Iron Garnet by Doping with Neodymium.

The effect of the substitution of Y3+ by Nd3+ on the structural and magnetic properties of neodymium-doped yttrium iron garnet, NdxY3−xFe5O12 with x in the range of 0–2.5, is presented. Oxide powders of Fe2O3, Nd2O3, and Y2O3 were mixed in a stoichiometric ratio and milled for 5 h using high-energy ball milling, before being uniaxially pressed at 900 MPa and annealed at 1373 K for 2 h to obtain NdxY3−xFe5O12 (0 ≤ x ≤ 2.5). It was found that the mechanical milling of oxides followed by annealing promotes the complete structural formation of the garnet structure. Additionally, the X-ray diffraction patterns confirm the complete introduction of Nd3+ into the garnet structure with a neodymium doping concentration (x) of 0–2.0, which causes a consistent increment in the lattice parameters with the Nd3+ content. When x is higher than 2.0, the yttrium orthoferrite is the predominant phase. Besides, the magnetic results reveal an increase in the Curie temperature (583 K) as the amount of Nd3+ increases, while there was enhanced saturation magnetization as well as modified remanence and coercivity with respect to non-doped YIG.

Nd3+ dopant influence on the structural and spectroscopic properties of microcrystalline La2Mo2O9 molybdate

In this paper we report the detailed analysis of both structural characterization by XRD, DSC, Raman, SEM techniques and high resolution spectroscopic properties of microcrystalline Nd3+-doped La2Mo2O9 (LAMOX) dilanthanum dimolybdate obtained by the conventional solid state reaction. Basing on the analysis of a series of compounds with a wide range of Nd3+ ion concentration we discovered that the amount of Nd3+ dopant substituting La3+ ions affects significantly on structural and spectroscopic properties. Pure Nd3+-doped phases with monoclinic structure (α-form, the space group P21) were observed for the concentration of optically active ion up to 15%. When the concentration of Nd3+ ions is higher a cubic structure (β-form, the space group P213) starts to form. However, up to concentration of 50mol% of the Nd3+ ion a mixture of the monoclinic and cubic phases has been observed. Pure cubic phase was obtained when the Nd3+ contents had reached 50mol%. The spectroscopic analysis has shown that the Nd3+-doped monoclinic phase might be useful for application in the future as phosphors and ultra-short pulses (pico, femto) laser materials. The cubic phase could be useful to fabricate transparent ceramics and might be an important challenge for laser applications.

Synthesis, characterization, and application of Nd, Zr–TiO2/SiO2 nanocomposite thin films as visible light active photocatalyst

A novel Nd, Zr–TiO2/SiO2 nanocomposite thin film was successfully prepared with various amounts of Nd3+ and Zr4+ as codopant ions for self-cleaning applications. In the first step, two types of Zr, Nd–TiO2/SiO2 thin films were prepared using ZrCl4 and ZrOCl2 compounds as a source of second doping agent ions. The result of the scanning electron microscopy (SEM) indicated that ZrOCl2 precursor produces a more monotonous thin film, but study of the photocatalytic activity of these thin films showed that ZrCl4-based thin film possess a more significant photocatalytic activity. Based on these results, ZrCl4 was chosen as a source of doping ion. Two kinds of Nd, Zr–TiO2/SiO2 nanocomposite thin films A and B were synthesized using various techniques. Type A thin film was coated on a glass substrate by heat treatment, but Type B was coated on polycarbonate sheets without any heat treatment process. The SEM images and XRD pattern showed that the optimum amount of doping ion in relation to Ti3+ is 0.1 %. In this circumstance, the most monotony of film was seen and the main formed phase was anatase. The sample structures were characterized by infrared spectroscopy. The nanocomposite films were found to be active for photocatalytic decomposition of methyl orange as an organic pollutant.

Microstructure and dielectric properties of Nd doped CaCu3Ti4O12 synthesized by sol–gel method

Ca(1−3x/2)NdxCu3Ti4O12 (x = 0, 0.1, 0.2 and 0.3) powders and ceramics were prepared by sol–gel method. Effect of Nd on microstructure and dielectric properties were investigated. XRD patterns suggest that pure perovskite-like CCTO phase were obtained after calcining at 800 °C for 2 h. SEM pictures reveal that particle size monotonously decreases from 250 to 120 nm with increase of Nd concentration. The lattice parameters show an increasing trend with the enhancing amount of Nd3+ substitution. The average grain size of CCTO ceramics decrease from 2.0 to 0.8 μm with increase in Nd doping, which indicates that high concentration of Nd inhibits grain growth of CaCu3Ti4O12. Both of the dielectric constant and dielectric loss decrease with increase in Nd concentrations. Ca(1−3x/2)NdxCu3Ti4O12 ceramics with x = 0.3 shows the lowest dielectric constant of 1.12 × 104 as well as the lowest dielectric loss value of 0.12 at 20 °C(10 kHz).

Double‐metal complexation of heterogels containing cyanobacterial polysaccharides

AbstractCryogenic‐transmission electron microscopy of metal complexes with cyanobacterial polysaccharides, sacran, extracted from Aphanothece sacrum biomaterials reveals that Nd3+ complexes form networks composed of thick strings with a thickness ranging 10–20 nm while Fe2+ ones make dense entanglement of very thin strings. When Fe2+ and Nd3+ double complexation occurs, dense nanonetworks composed of thick strings with a thickness around 10 nm are formed. Next we prepared heterogels by crosslinking poly(vinyl alcohol) chains in the presence of sacran and investigated the effects of double complexation on metal sorption. The amount of Nd3+ sorbed into the heterogels in the 1 : 1 miscible solution of Fe2+ and Nd3+ is higher than that in the solution containing only Nd3+, suggesting that Fe2+ assists the Nd3+ sorption. In addition, it is found that the amount of sorbed Nd3+ is much higher than that of sorbed Fe2+ even in the acidic condition of pH 2. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Nd3+ → Yb3+ energy transfer in a codoped metaphosphate glass as a model for Yb3+ laser operation around 980 nm

A complete spectroscopic investigation of a metaphosphate glass with composition Pb(PO3)2 doped with various amounts of Nd3+ and Yb3+ (1 up to 10 at.%) is reported. Efficient Nd3+ → Yb3+ energy transfers occur both radiatively and non-radiatively, the latter being dominant and partly resonant and partly phonon-assisted by phonons of the order of 950 cm−1, which fits well with the reported Raman spectrum of the material. These transfers mainly concern the 4F3/2 → 4I9/2 emission and the 2F7/2 → 2F5/2 absorption transitions of the Nd3+ and Yb3+ ions around 900 nm, respectively. They are analysed both via spectral and temporal data. The results show that about 5% Nd3+ and 5% Yb3+ ions have to be incorporated to reach energy transfers exceeding about 65%, which is in agreement with data recently reported in the case of a YAl3(BO3)4 crystal. Simulations based on the obtained data show that laser thresholds of a few tens of mW should be easily attainable by operating the materials in a channel waveguide configuration.

Experimental studies of spontaneous emission from dopants in an absorbing dielectric

We report the first measurements, to our knowledge, of the modification of spontaneous emission rates of Eu3+ ions in the visible region owing to an absorbing medium. Precise levels of the absorption coefficient are introduced by codoping with different amounts of Nd3+. We use a binary glass system PbO-B2O3 as the host, the compositional variation of which leads to a change in the real part of the refractive index. Measured lifetimes are found to follow the real cavity model, and the data are analyzed by the model proposed by Scheel et al. [Phys. Rev. A 60, 4094 (1999)]. We give estimates of the parameter that is related to the radius of the cavity around Eu3+.

Crystallization study of (TiO2, ZrO2)-rich SiO2-Al2O3-CaO glasses Part I Preparation and characterization of zirconolite-based glass-ceramics

Nuclear power reactors generate long-lived radionuclides such as minor actinides (Np, Am, Cm) which are mainly responsible for the long term radiotoxicity of high level nuclear wastes obtained after reprocessing of nuclear spent fuel. Specific highly durable matrices such as glass-ceramics appear as good candidates for the immobilization of minor actinides. This work concerns the synthesis and the characterization of zirconolite (CaZrTi2O7) based glass-ceramics prepared by controlled devitrification of (TiO2, ZrO2)-rich SiO2-Al2O3-CaO parent glasses for which neodymium was selected to simulate the radioactive trivalent minor actinides. The present study reports the effect of increasing TiO2, ZrO2 and CaO amounts in glass composition on the structure and the composition of the zirconolite crystals (formed as the only crystalline phase in the bulk of the glass), on their nucleation rate I(Z) and on the volume proportion of crystalline phase V of the glass-ceramics. It appears that I(Z) and V strongly increase when the parent glass composition changes. Neodymium electron spin resonance (ESR) shows that the total amount of Nd3+ ions incorporated in the zirconolite phase increases with TiO2, ZrO2 and CaO amounts in parent glass composition.

Neodymium cations Nd3+ were transported to the interior ofEuglena gracilis 277

Euglena gracilis 277, a unicellular green alga, demonstrated remarkable ability to transport Nd3+ to the cell compartments. For a given amount of Nd3+ and cells, the results of ICP-AES indicated that the cellular uptake of Nd3+ was independent of Nd3+ concentration in the bulk solution. The average uptake of Nd3+ per cell (mNd) is proportional to a parameter ξ — the ratio of neodymium content to the cell counts of the system. A novel approach for probing cellular neodymium by tetraiodotetra chlorofluorescein (I4TCF) has been devised. Data derived from the cryosections of I4TCF-Nd3+ stained cells and EDAX of the fast freezing ultrathin cryosections indicate that Nd3+ is distributed over the cell compartments. Chloroplasts are the major compartments as the residence of Nd3+ in the alga. The transport should be against a concentration gradient of Nd3+ on the order of five, even higher. It is proposed that a calcium ion channel would play an important role in the Nd3+ transportation.