Preparation Of Nd Research Articles

Preparation of Nd–Fe–B Films via a Low-Temperature Process

Preparation of Nd–Fe–B Films via a Low-Temperature Process

High‐Performance Nd: AIZO/Al2O3 Dual Active Layer Design Without Thermal Annealing: High‐Speed Electron Transport and Defect Modification in Thin Film Transistors

Flexible wearable electronics have been developing rapidly in recent years, and one of its core devices, thin‐film transistor (TFT), is also attracting attention. Current TFT preparation processes usually require high annealing temperatures (>350 °C), which is not conducive to their application on most flexible substrates (PET, PEN, nanopaper, etc.). In this article, a strategy for the room temperature preparation of Nd:AIZO/Al2O3 dual‐layer TFT devices is proposed, which has appreciable electrical properties without additional annealing treatment. Taguchi orthogonal experimental methods are used to investigate the effects of three essential process parameters on the performance of the films and devices. As Nd:AIZO deposition time decreases and Al2O3 oxygen percentage and time during deposition increase, the μsat and SS of TFT devices are improved. With the preferred combination of parameters applied to the device preparation, the device exhibits a saturation mobility μsat of 24.3 cm2 V−1 s−1, a threshold voltage Vth of −1.4 V, a subthreshold swing SS of 0.21 V decade−1 and an Ion/Ioff ratio of 4.26 × 108. The ultra‐thin Al2O3 layer act as defect modification and form high‐speed electron transport in channel layer. The room temperature preparation of the dual‐layer TFT process proposed in this article is compatible with large‐size low‐cost flexible substrates. It has great potential for application in green flexible wearable electronics.

Study on the Preparation of Nd–Doped Zinc Cobalt Oxide Porous Film and Its Electrochemical Properties

In this paper, ZnCo2O4(Nd–ZnCo2O4) films were prepared using a hydrothermal method and an electrodeposition method. We characterized the samples using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The effect of Nd–ZnCo2O4 doping on the stability of the materials was studied. The results show that the Nd−ZnCo2O4 prepared in the experiment presents a porous network structure, no other impurity peaks and impurity elements exist, and the purity is high. In the experiment, the electrochemical properties of Nd−ZnCo2O4 were studied. When the current density is 3 A·g−1, the specific capacitance F·g−1 of the electrode is 1982 F·g−1. When the current density is changed 100 times, and every time it is changed back to 3 A·g−1, the specific capacitance F·g−1 is 1973 F·g−1, which is 99.5% of the initial specific capacitance F·g−1. 1982 F·g−1 indicates that Nd−ZnCo2O4 has good stability and can be reused many times. In the cycle stability performance test of Nd–ZnCo2O4//CNTs devices, when the current density is 3 A·g−1, the specific capacitance is 180 F·g−1. After 10,000 cycle charge discharge tests, the specific capacitance F·g−1 becomes 162 F·g−1, maintaining 90% of the initial specific capacitance. These results show that the electrode material has a long cycle life and good cycle stability.

37.1: Invited Paper: A Room‐Temperature Manufacturing Strategy: Nd:AIZO/Al2O3 Thin‐Film Transistor

Metal oxide semiconductors (MOS) have shown great application potential as the active layer of thin film transistors (TFTs). However, MOTFTs usually require an annealing process(≥300°C), which is not conducive to its application in flexible substrates. Here, we establish a Room‐Temperature manufacturing strategy of TFT, which consist of a Nd:AIZO/Al2O3 bilayer structure as the active layer. The Nd:AIZO/Al2O3 bilayer TFTs without further thermal annealing processing show reasonable device characteristics with mobility(µsat) of 28.7 cm2 V‐1 s‐1, an Ion/Ioff ratio of 108, a threshold voltage(Vth) of 0.2 V, and a subthreshold swing(SS) of 0.25 V/decade. The room‐ temperature preparation of Nd:AIZO/Al2O3 bilayer TFT is compatible with low‐cost flexible substrates, which is anticipated in the application of large‐size flexible electronic devices, especially of the "green" flexible display area.

Hydrothermal Synthesis of Nd–Fe–B Nanoparticles with Enhanced Magnetic Properties by Nd Content Tunning and Dy Doping

This paper reports a novel, facile and low-energy consumption chemical method to synthesise Nd–Fe–B and Dy-substituted Nd–Fe–B magnetic nanoparticles with enhanced magnetic properties. NdxFe95-xB5 (15≤ x≤ 40) and Nd35-yDyyFe60B5 (0≤ y ≤8) magnetic nanoparticles were synthesised using a hydrothermal method, followed by a reduction-diffusion annealing process. We carried out a detailed experimental study of the effects of Nd content and Dy substitution on the phase assemblage and magnetic properties in the two systems. The results indicated that the coercivity of the Nd–Fe–B powders increased with increasing Nd content, and the maximum coercivity measured was 262.5 kA/m for Nd40Fe45B5 (by weight percentage). Conversely, the saturation magnetisation decreased with increasing Nd content. When the addition of Dy was less than 8 wt%, both the coercivity and the saturation magnetisation varied monotonically with the amount of Dy added, and a coercivity of 548.9 kA/m was measured for Nd27Dy8Fe60B5. The results show that hydrothermal method followed by a reduction-diffusion process is simple and economical in preparing Dy-substituted Nd2Fe14B magnetic nanoparticles, and the controllable and enhanced magnetic properties can be realised by simply adjusting the ratio of raw materials. This is also a good complement to the preparation of Nd–Fe–B nanoparticles by chemical methods.

Three-dimensional macroporous wood-based selective separation membranes decorated with well-designed Nd(III)-imprinted domains: A high-efficiency recovery system for rare earth element

Three-dimensional (3D) basswood materials, for the first time, were successfully used for the construction of rare-earth Nd(III)-imprinted nanocomposite membranes. Herein, polydopamine (PDA)-modified layers could be initially synthesized on basswood surfaces. After the double-bonded modification procedure, the 3D wood-based ionic imprinted membranes (3DW-IIMs) system was finally accomplished by developing a re-modified two-step-temperature free radical polymerization process. The as-design PDA@basswood surface structure was first proposed and applied as imprinting-initiated factors for the preparation of Nd(III)-imprinted sites. Importantly, excellent rebinding capacity (120.87 mg g−1), adsorption kinetics and permselectivity coefficients (more than 10) were achieved successfully. Furthermore, an important research result had also been found that the PDA-modified layers caused significant promotions to the rebinding capacities of the as-prepared 3DW-IIMs, that is to say, more and more Nd(III)-imprinted sites could be synthesized because of the PDA-modified surfaces. The as-obtained selective rebinding and separation results together with the green natural wood-based materials strongly demonstrated that our synthesis methodology of 3DW-IIMs had great potential for applications in various fields of rare earth separation, chemical industry, and environment protection.

Preparation and characterization of neodymium hydroxide powder via the hydration method

The preparation of Nd(OH) 3 powder by the direct hydration method using Nd 2 O 3 as a raw material was studied, and the effects of stirring mode, H 2 O and Nd 2 O 3 molar ratio, stirring rate, and reaction time on temperature change and conversion rate in a hydration system were analyzed. The reasonable process conditions for the direct hydration of Nd(OH) 3 by Nd 2 O 3 were then determined. Process, morphology, and structure were considered in the preparation of neodymium hydroxide powder, and its composition was investigated by X-ray powder diffraction, scanning electron microscopy, laser particle size analysis, thermogravimetric differential thermal analysis, and chemical analysis. It has been proved that the process is simple and feasible, in line with the concept of modern green chemistry, and the products also meet the market requirements. The hydration method is that Nd 2 O 3 and H 2 O are directly mixed in the heat insulation reactor that is an environmentally friendly method for the preparation of neodymium hydroxide. Experiments show that this method is feasible in industry which involves a short process and takes into account the cost and energy savings. The particle size of the product is small (629 nm) and the dispersion of the product is good.

Production of Permanent Magnets for Magnetically Hard Alloys Using Rare-Earth Metals

A requirement for improving powder metallurgy technology of alloys for permanent magnets containing rare-earth metals based on the use of secondary resources and a replacement of rare-earth metals and fine control of the semifinished products chemical composition is demonstrated. These approaches are realized successfully in the preparation of Nd–Fe–B system magnetically hard materials by a binary mixture method using rare earth metal hydrides and their alloys. Analysis of the magnetic properties of Sm–Co–Cu–Fe–Zr system permanent magnets according to the results of the primary ingot chemical composition control minimizes production costs.

Inducing magnetic anisotropy and optimized microstructure in rapidly solidified Nd–Fe–B based magnets by thermal gradient, magnetic field and hot deformation

Direct preparation of Nd–Fe–B alloys by rapid solidification of copper mold casting is a very simple and low cost process for mini-magnets, but these magnets are generally magnetically isotropic. In this work, high coercivity Nd24Co20Fe41B11Al4 rods were produced by injection casting. To induce magnetic anisotropy, temperature gradient, assisted magnetic field, and hot deformation (HD) procedures were employed. As-cast samples showed non-uniform microstructure due to the melt convection. The thermal gradient during solidification led to the formation of radially distributed acicular hard magnetic grains, which gives the magnetic anisotropy. The growth of the oriented grains was confirmed by phase field simulation. A magnetic field up to 1 T applied along the casting direction could not induce significant magnetic anisotropy, but it improved the magnetic properties by reducing the non-uniformity and forming a uniform microstructure. The annealed alloys exhibited high intrinsic coercivity but disappeared anisotropy. HD was demonstrated to be a good approach for inducing magnetic anisotropy and enhanced coercivity by deforming and refining the grains. This work provides an alternative approach for preparing fully dense Nd-rich anisotropic bulk Nd–Fe–B magnets.

An electrodeposition metal layers method for magnetic powders and warm-pressing preparation of Nd–Fe–B/Sn-bonded magnets

The method of magnetic stirring in fluid-bed galvanic deposits was used for cladding low-melting-point metallic tins onto the surface of rapid quenching Nd–Fe–B magnetic powders. This form of bonding was also used to make Nd–Fe–B/Sn composite magnets by warm pressing at 300 °C. The tin-plating layers of the Nd–Fe–B magnetic particles were observed by scanning electron microscope (SEM). The magnetic properties of the coated and uncoated powders were examined by vibrating sample magnetometer (VSM), respectively. Furthermore, both the compressive strength and magnetic properties of Sn-coated Nd–Fe–B/Sn-bonded magnets were measured. The results indicate that not only the tin plated and magnetic powders were bonded closely, but also the content of tin-plated layers can be controlled by the electrical current. The (BH)max and Br value of magnetic powders decrease with the increasing content of plated tin. An increase in the tin-plated content results in an elevation in magnetic properties of composite magnets by warm-pressing preparation. The composite magnets exhibit excellent integrated magnetic property when the content of Sn was 5.079 wt.%, at (BH)max = 113.7 kJ m−3, Br = 0.821 T, Hcj = 732.6 kA m−1. The results indicate that the required electrodeposited tin is less than 5 wt.% achieving the same magnetic properties and compressive strength which demands 10 wt.% tin in mechanical mixing method.

Preparation of Nd–Fe–B sintered magnets from HDDR-processed powder

The electric-current sintering technique was used to fully densify hydrogenation–disproportionation–desorption–recombination (HDDR)-processed Nd–Fe–B powder at temperatures below the grain growth temperature in order to produce high-coercive bulk magnets. However, the sintered magnets exhibited anomalous coercivity reduction that depended on sintered density. Reheating examination of the sintered magnets revealed that the reduced coercivity was increased in proportion to the heating temperature, resulting in complete recovery of coercivity. As a result, the combination of electric-current sintering and post-annealing produced sintered magnets with a coercivity of 15kOe. Scanning and transmission electron microscopy revealed no evidence that associated the anomalous coercivity reduction and recovery with grain boundary morphology. On the other hand, various HDDR powders with different particle sizes were sintered, and finer powders yielded lower coercivity after sintering, implying that the anomalous coercivity reduction was associated with particle surface oxides of the raw powder.

Correction: Preparation of Nd–Fe–B by nitrate–citrate auto-combustion followed by the reduction–diffusion process

Correction for ‘Preparation of Nd–Fe–B by nitrate–citrate auto-combustion followed by the reduction–diffusion process’ by Hao Xuan Ma, et al., Nanoscale, 2015, 7, 8016–8022.

Preparation of Nd-Fe-B by nitrate-citrate auto-combustion followed by the reduction-diffusion process.

The Nd2Fe14B alloy has been successfully synthesized by nitrate-citrate auto-combustion followed by the reduction and diffusion process with low energy consumption. H3BO3, Fe(NO3)3·9H2O, and Nd(NO3)3·6H2O were used as precursors and citric acid was used as the chelating ligand of metal ions. Ammonia water was used to adjust pH to 7. CaH2 was used as a reducing agent for the reduction and diffusion process. NdFeO3 and Fe2O3 were produced during auto-combustion of gel. The combustion process of the gel was investigated by TGA/DTA curve measurements. The phase compositions were studied by XRD measurements. The differences of the overall morphology and magnetic properties were measured by SEM, TEM and vibrating sample magnetometry (VSM) at 300 K. The comparison of the magnetic properties of the reduced samples between the pellet type and the random powder type was done with VSM and it showed better magnetic properties of the pellet type Nd2Fe14B. Making a compact pellet type sample for reduction is more efficient for solid reduction and phase transition for higher coercivity.

Amine-Assisted Synthesis and Characterization of Lanthanide Hydroxide Nanorods and Derived Oxides

One-step synthetic route has been developed for the preparation of Nd ( OH )3 nanorods in the presence of n-butylamine. The as-prepared sample is in hexagonal phase with good crystallinity, and made up of highly dispersed nanorods of 14–15 nm in diameter and up to 40–50 nm in length at 120°C for 24 h. Optical measurements show that these nanorods have intensive photoluminescence (PL) at room temperature and have the potential to become optical materials. Thermogravimetric analysis (TGA) of the Nd ( OH )3 nanorods reveals that the nanorods remain stable up to 220°C and decompose to the derived oxide of Nd 2 O 3 at higher temperatures. The derived oxides show the promise active catalyst for the oxidation of carbon monoxide. In addition, this synthetic route has been developed for the synthesis of a series of other lanthanide hydroxides nanorods including Pr ( OH )3, Sm ( OH )3, Eu ( OH )3, Gd ( OH )3, Tb ( OH )3 and Dy ( OH )3, and their PL properties, thermostability and catalytic properties are investigated.

Preparation of Nd:YAG Nanopowders by the Urea Co-Precipitation

Nd:YAG nanopowder was prepared by urea co-precipitation method. XRD, TG-DTA, SEM and spectra analysis were utilized to study the properties of the powder. Results indicated that fine Nd:YAG nanopowder can be acquired at 1000°C for 10h. The fluorescence spectra shown that the strongest peak was located at 1061nm, corresponding to the 4F3/24I11/2 energy level transition of Nd3+ ion.

Development of methods for preparation of Nd : YAG nanoparticles

Methods for synthesis of nanosized precursors for the preparation of yttrium-aluminum garnet from organic-inorganic derivatives of yttrium and aluminum have been developed. It has been shown that most of the methods for carrying out the process result in the formation of precursors with high specific surface area. The precursor obtained using nanosized powder of aluminum oxide and yttrium acetylacetonate is the least agglomerated. The data obtained can be used when preparing optical ceramic from yttrium-aluminum garnet.

Preparation of Nd and Co Co-Doped BiFeO<sub>3</sub> Thin Films Co-Doping Nd and Co by Sol-Gel Method

BiFeO3 thin films co-doping Nd and Co were prepared on FTO/glass substrate by sol-gel method with Bi(NO3)3•5H2O, Fe•(NO3)3•9H2O, Nd(NO3)3•6H2O and Co(NO3)2•6H2O as raw materials, 2-methoxyethanol together with acetic anhydride as a solvent. XRD, FE-SEM, Agilent E4980A Precision LCR Meter and TF 2000 Ferroelectric Analyzer were used to characterize the structure, morphology, dielectric property and ferroelectric property of the BiFeO3 thin films. The results show that after Nd and Co co-doping, the BiFeO3 thin films still keep the perovskite structure. The crystal structure turns square or orthogonal from rhombus. The thickness of the BiFeO3 thin films is about 500nm and the grain size is 80nm to 30nm. BiFeO3 thin films co-doping Nd and Co have the larger dielectric constant and the lower dielectric loss compared with Nd doping. BiFeO3 thin films co-doping Nd10% and Co1% have the dielectric constant of over 170 and the dielectric loss of below 0.03. Both have the better frequency stability. Co-doping Nd and Co could decrease the coercive electric field of BiFeO3 thin films.

Effect of annealing on the optical properties of Nd:YAG transparent ceramics

The Nd:YAG transparent ceramics were fabricated by vacuum sintering at 1750 °C for 20 h, where the raw nanopowders were synthesized by a modified co-precipitation method. Subsequently the Nd:YAG ceramic specimens were annealed or even re-annealed in air or vacuum at 1250–1500 °C for 20 h. The Nd:YAG ceramic specimens were investigated by X-ray diffraction, ultraviolet spectroscopy, inductively coupled plasma atomic emission spectroscopy, electron paramagnetic resonance spectroscopy and scanning electron microscopy. The results showed that post-annealing could improve the optical properties and microstructure of Nd:YAG transparent ceramics. By air annealing, the in-line transmittances of the specimens increased, mainly due to the decrease of oxygen vacancies concentration in specimens. The air annealing at 1450 °C for 20 h was optimum for preparation of Nd:YAG transparent ceramics. Furthermore, the red shift of UV absorption edge after air annealing could be attributed to the absorption by Fe 3+ charge transfer bands.

Preparation of Nd:Y3Al5O12 nanocrystals by low temperature glycol route

AbstractY3Al5O12, yttrium aluminum garnet (YAG) single crystals are extensively used as host materials for solid‐state lasers. The materials in nano sizes are of immense importance due to their fascinating physical and chemical properties. Nanocrystals of Nd doped YAG were synthesized by low temperature glycol route. This method consists of a mixing of nitrates in an aqueous media at reasonably low temperatures. The Nd doping concentration was optimized and kept at 2 mol%. The prepared material was annealed at different temperatures. Single phase Nd:YAG nanocrystals were obtained at 850 °C. The prepared nanocrystals were characterized by XRD, SEM and TEM techniques for the crystalline phase, crystalline size and structure. The crystalline sizes were obtained in the range of ∼20–30 nm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Microwave-assisted synthesis and characterization of Nd 1.5Mg 17Ni 0.5–Fe 3O 4 hydrogen storage composite

This work reports the preparation of Nd 1.5Mg 17Ni 0.5–Fe 3O 4 hydrogen storage composite in a single mode 2.45 GHz microwave cavity. The physicochemical properties (thermodynamic and kinetic characteristics, hydrogen absorption/desorption properties, thermal behavior, phase composition and morphology) were characterized by pressure-composition isotherms, differential scanning calorimetry, X-ray diffraction, scanning electron microscope with an energy dispersive X-ray spectrometer, transmission electron microscopy, and laser granulometry. The proposed microwave synthesis, in contrast with conventional sintering method, offers rapid heating, makes homogenous composition and hence improves the hydrogen storage properties of the composite.