Small Amount Of Nd Research Articles

Interface reaction and properties of Sn3.5Ag0.5Cu-xNd solder joints subjected to isothermal aging

In this paper, rare earth Nd with various contents (0, 0.04 and 0.5 wt.%) was incorporated into Sn3.5Ag0.5Cu (SAC) solder. The influence of rare earth Nd on the interface reaction, microstructure development, mechanical behavior and wettability were investigated by scanning electron microscopy (SEM), joint strength measuring instrument, and wetting balance method. Adding a small amount of Nd can suppress the growth of interface IMC layer and subdivide the joint microstructure. The mechanical behavior and wettability were also improved efficiently. In the N2 atmosphere, the wettability of solder is better. In addition, the mechanical behavior of three kinds of solder joints decreases with increasing aging time, but the degree of decline of 0.04Nd solder joint is relatively slow.

Creep properties and microstructure of a Mg-6Al-1Nd-1.5Gd alloy at temperatures above 150 °C

Compressive creep behavior of a Mg-Al alloy containing a small amount of Nd and Gd (Mg-6Al-1Nd-1.5Gd) was investigated at temperatures from 150 °C to 200 °C under a constant applied stress of 90 MPa, and its microstructure before and after creep testing was compared. Results showed that steady-state creep rate of the alloy was only 1.946 × 10−8 /s at 150 °C, and was increased by four times and almost one order of magnitude at 175 °C and 200 °C, respectively. The microstructure of the alloy mainly consists of α-Mg, β-Mg17Al12 phases, and Al2RE phases, which were distributed both in dendrites of α-Mg and at grain boundaries originally. After creep for 120 h, more Al2RE phases were aggregated at grain boundaries. The continuous β-Mg17Al12 phase turned into dispersed dot-like or blocky particles. As the test temperature increased, the number of dislocation lines gradually increased due to the increase of creep strain. Meanwhile, dislocation tangle and dislocation pile-ups occurred near grain boundaries. However, obvious slip traces and slip lines appeared inside α-Mg dendrites at 175 °C and 200 °C, respectively, indicating that 〈c + a〉 non-basal slip system was activated, creep resistance decreased dramatically.

Influence of Nd and Y on texture of as-extruded Mg–5Li–3Al–2Zn alloy

Mg–5Li–3Al–2Zn alloys with the additions of Y and Nd were prepared using induction melting furnace under the atmosphere of pure argon; then they were extruded. The textures of the as-extruded alloys were analyzed by pole figures and electron backscatter diffraction. Results show that the addition of a small amount of Nd can weaken the basal texture. The further increase of Nd content has no corresponding further influence on texture. When a small amount of Y is used to replace Nd, the basal texture can be further weakened and the prismatic slip system can be further activated. In the alloy of Mg–5Li–3Al–2Zn–1.2Y–0.8Nd, the basal textures almost vanish.

Thin-Film Transistors With Neodymium-Incorporated Indium–Zinc-Oxide Semiconductors

A thin-film transistor (TFT) with a neodymium-doped indium–zinc-oxide (NIZO) channel layer was fabricated. It was found that the Nd element uniformly distributed in the whole NIZO films, which revealed a nanocrystalline structure, implying that Nd was incorporated into the IZO lattice rather than segregated as clusters. The NIZO TFT annealed at 300 °C showed a saturation mobility of 22.7 cm $^{2}\text{V}^{-1}\text{s}^{-1}$ , a turn-ON voltage of −1.32 V, a subthreshold swing (SS) of 0.23 V/decade, and small turn-ON voltage shift under negative gate bias stress (−0.42 V) and positive gate bias stress (0.40 V). As the annealing temperature increased, the threshold voltage of the NIZO TFTs became more and more negative. Compared with IZO TFTs without Nd, NIZO TFTs exhibited lower SS and less turn-ON voltage shift as the annealing temperature increased. It was found that the free carriers of NIZO can be lowered even with a small amount of Nd ( $\sim 1$ %). When annealed at a temperature of as high as 400 °C, the oxygen out-diffusion effect of NIZO was not as serious as that of IZO. Detailed studies showed that Nd atom could suppress the formation of oxygen vacancies due to the strong bonding strength of Nd–O (703 kJ/mol).

Structural, optical and electrical properties of Nd-doped SnO2 thin films fabricated by reactive magnetron sputtering for solar cell devices

The use of photon conversion layers is an interesting way to improve the overall efficiency of solar cells. Herein we report on Nd-doped SnO2 thin films with photon management property inserted further into CIGS based solar cells. The functionalized layers were deposited by reactive magnetron sputtering whose structural, optical and electrical properties were tuned by varying the deposition temperature. Careful analysis of the structure using XRD and XPS showed that the tetragonal rutile SnO2 phase can be obtained at a deposition temperature as low as 100°C. Transparency was found to be as high as 90% for all layers while the absorption edge is found to increase when increasing the deposition temperature up to 300°C. The photoluminescence measurements under 325nm UV laser excitation showed that 100°C is needed for the optical activation of the rare earth. Despite the small amounts of Nd (around 0.62at%), intense and narrow emission bands have been collected in the Near Infrared Region (NIR) which are characteristics of Nd3+ ions whose the ionic state was confirmed by the 3d XPS core levels. Thus, the emission spectra cover a good part of the spectrum useful to the solar cell. Photoluminescence excitation spectroscopy experiments were also carried out on Nd:SnO2 samples to get insights on the energy transfer. By exciting in the deep UV from 250 to 400nm intense Nd emission was collected giving an experimental evidence of the down-shifting process through a resonant energy transfer from the SnO2 host matrix to the Nd3+ ions. Hall Effect measurements showed that the n-type character and good conductivity of the Nd doped SnO2 films can be correlated to the highest optical activity of Nd in the matrix. An optimal condition is found for the Nd-doped SnO2 film grown at 300°C for which the highest PL and the best electrical data were measured. Finally, we show that the implementation of such optimized Nd–SnO2 films on CIGS based solar cells serving as a transparent conducting oxide and a down shifting converter results in the best power conversion efficiency.

Improvement of corrosion resistance and biocompatibility of rare-earth WE43 magnesium alloy by neodymium self-ion implantation

Without introducing extraneous elements, a small amount of Nd is introduced into rare-earth WE43 magnesium alloy by ion implantation. The surface composition, morphology, polarization, and electrochemical properties, as well as weight loss, pH, and leached ion concentrations after immersion, are systematically evaluated to determine the corrosion behavior. The cell adhesion and viability are also determined to evaluate the biological response in vitro. A relatively smooth and hydrophobic surface layer composed of mainly Nd2O3 and MgO is produced and degradation of WE43 is significantly retarded. Furthermore, significantly enhanced cell adhesion and excellent biocompatibility are observed after Nd self-ion implantation.

Enhanced ferroelectricity, piezoelectricity, and ferromagnetism in Nd-modified BiFeO3-BaTiO3 lead-free ceramics

Lead-free multiferroic ceramics of 0.75Bi1−xNdxFeO3 − 0.25BaTiO3 + 1 mol. % MnO2 were prepared by a conventional ceramic technique and their structure, piezoelectricity, and multiferroicity were studied. The ceramics sintered at 890–990 °C possess a pure perovskite structure. A morphotropic phase boundary of rhombohedral and monoclinic phases is formed at x = 0.05. A small amount of Nd improves the ferroelectric and piezoelectric properties of the ceramics. The ferroelectric-paraelectric phase transition becomes gradually diffusive with x increasing. After the addition of Nd, the ferromagnetism of the ceramics is greatly enhanced by ∼320%. The increase in sintering temperature improves significantly the ferroelectric, piezoelectric, and ferromagnetic properties of the ceramics. The ceramics with x = 0.05 sintered at 950–990 °C possess improved ferroelectricity, piezoelectricity, magnetism and insulation with Pr of 16.5–17.5 μC/cm2, d33 of 113–121 pC/N, Mr of 0.127–0.138 emu/g, R of ∼5 × 109 Ω·cm and high TC of 473–482 °C, indicating that the ceramic is a promising candidate for room-temperature multiferroic and high-temperature piezoelectric materials.

Effect of Nd Substitution on Magnetic and Microwave Absorption Properties of Nanocrystalline Sr(MnSn)0.5Fe11O19

The preparation of Sr1-xNdx(MnSn)0.5Fe11O19 M-type hexaferrites powders by a citrate sol-gel method was investigated. The samples were determined by X-ray diffraction (XRD) and transmission electron microscope (TEM). Microwave absorption properties of hexaferrite- acrylic resin composites were measured using SWR (standing-wave-ratio) method in the range of 12 to 20 GHz. It was shown that small amounts of Nd+3 substitution could significantly modify the microwave electromagnetic parameters. Furthermore, the investigation indicated that substitution of Nd+3 ions for Sr+2 ions in Sr(MnSn)0.5Fe11O19 resonant frequency would move toward higher frequency. The results showed that the powder possesses excellent microwave absorption properties. A minimum reflection loss of –43 dB was observed for the composite, where x = 0.03. A broad bandwidth of microwave absorption (with a –10 dB reflection loss as a reference) is predicted in the composite samples containing the ferrite powders of x=0.02, and x=0.03 in Ku-band frequencies. Keywords: Chemical synthesis, magnetic materials, magnetic properties, nano crystalline materials.

Modification of thermoelectric properties in Ca3Co4Oy ceramics by Nd doping

Ca3−xNdxCo4Oy polycrystalline thermoelectric ceramics with small amounts of Nd have been synthesized by the classical solid state method. X-ray diffraction data have shown that all the Nd has been incorporated into the Ca3Co4O9 and Ca3Co2O6 phases and no Nd-containing secondary phases have been produced. Apparent density measurements have revealed that all samples are very similar, with densities around 70 % of the theoretical one. Electrical resistivity decreases in all Nd-doped samples, compared with the pure one, while Seebeck coefficient remains constant for all samples. The improvement in resistivity leads to higher power factor values than the obtained for the undoped samples.

Structural, dielectric and magnetic properties of Nd-doped Co 2Z-type hexaferrites

Z-type hexaferrites doped with Nd 3+, Ba 3− x Nd x Co 2Fe 24O 41 ( x = 0, 0.05, 0.10, 0.15, and 0.25), were prepared by solid-state reaction. The effect of the Nd 3+ ions substitution for Ba 2+ ions on the microstructure and electromagnetic properties of the samples was investigated. The results reveal that an important modification of microstructure, complex permeability, complex permittivity, and static magnetic properties can be obtained by introducing a relatively small amount of Nd 3+ instead of Ba 2+. SEM image shows that the grains of the ferrites doped with Nd 3+ were smaller, more perfect and homogeneous than that of the pure ferrite. The real part ( ɛ′) of complex permittivity and imaginary part ( ɛ″) increase at first, and then decrease with increasing Nd content. At low frequency, the imaginary part μ″ of complex permeability decreases with Nd content and then increases when frequency is above 7.0 GHz. The magnetization ( M s ) and the coercivity ( H c ) are 79.38 emu g −1 and 36.94 Oe for Ba 2.75Nd 0.25Co 2Fe 24O 41. The data of magnetism show that the ferrite doped with Nd 3+ ions is a better soft magnetic material due to the higher magnetization and lower coercivity.

Effect of Co and Dy substitutions on the structure and magnetic properties of Nd–Fe–C alloys prepared by a re-milling process

The effect of Co and Dy susbstitions on the structure and magnetic properties of Nd Fe C alloys prepared by a re-milling process has been investigated.The main magnetic phase Nd(2)(Fe,Co)(14)C coexists with a small amount of Nd(2)C(3) and Nd-rich phase in N(11)Fe(76) Co C(8) (0 <= x <= 20) alloys. The Co substitution for Fe enhances the Curie temperature T(c) and magnetic properties of the alloys. The remanence 4 pi M(r) saturation magnetization 4 pi M, and maximum energy product (BH)(max) of the N(16)Fe(76) Co C(8) (0 <= x <= 20) alloys increase up to a maximum tor x = 10. For N(16)Fe(06) C(10)C(8) (0 <= y <= 16) alloys prepared by re-milling and subsequent annealing, the introduction of Dy enhances the intrinsic coercivity due to the increase of anisotropy of the Nd(2)Fe(14)Co-type phase. (c) 2008 Elsevier B.V. All rights reserved.

Nd L3-edge x-ray absorption near-edge structure spectroscopy of nanocrystal-dispersed soft-magnetic alloys containing very small amounts of Nd

The Nd L3-edge XANES spectra of Nd-added FINEMET type soft magnetic alloys were characterized. Meltspun amorphous metallic alloys with compositions of Fe73.5Si13.5B9Cu0.5Nb3Nd0.5 and Fe73.5Si13.5B9Nb3Nd1 were heart-treated at 850 K for various durations up to 1 h in order to induce crystallization of nanocrystalline phases inside the alloys. The introduction of small amounts of Nd to the FINEMET-type alloys resulted in enhanced crystallization temperatures. The structural evolution of Nd over time was inferred based on changes of the Nd L3-edge x-ray absorption near-edge structure spectra. When coexisting with Cu atoms, Nd atoms clustered at the early stage of heat treatment and generally remained unaltered over time. In the absence of Cu atoms, however, the neighboring atoms of Nd changed over time. Magnetic properties of the heat-treated samples were discussed in connection with such local structural changes occurring at Nd sites in addition to the typical role of Cu atoms in crystallization behaviors.

Influence of a small addition of Nd on structure and magnetic properties of nanocrystalline Fe–B alloys

The influence of the addition of a few atomic percent of Nd on the structure and magnetic properties of Fe–B alloys was investigated. It is found that nanocrystalline Fe–B alloys with a small amount of Nd consist of body-centered-tetragonal Fe 3B and α-Fe phases. A small addition of Nd causes a dramatic change of magnetic properties from soft magnetic to hard magnetic. With increasing Nd content the coercivity increases from 0.2 to 2.3 kOe. High remanence and maximum energy product have been obtained in (Fe,Nd) 3B/α-Fe magnets and is explained by exchange coupling at interface separating nanocrystalline hard magnetic phase (Fe,Nd) 3B and soft magnetic phase α-Fe.

Structure and magnetic properties of Nd xFe 83− xB 17 alloys

The crystallization, crystal structure, microstructure and magnetic properties of Nd x Fe 83− x B 17 alloys have been investigated. It is found that with increasing Nd content, the crystallization temperature of amorphous Nd x Fe 83− x B 17 alloys increases, but the magnetization decreases. On annealing, amorphous alloys crystallize to different crystalline phases and the coercivity increases, depending strongly on Nd content. A new hard magnetic alloy of Nd 3Fe 80B 17 has been obtained. This alloy consists of α-Fe and Fe 3B phase containing a small amount of Nd. The hard magnetic properties originate from the Fe 3B phase containing Nd.

Defect Engineering for Control of Polarization Properties in SrBi2Ta2O9

Defect engineering to design for remanent polarization (Pr) and coercive field (Ec) in SrBi2Ta2O9 (SBT) is proposed. Cation vacancies coupled with substituents or oxide vacancies are shown to play an essential role in determining the polarization properties. High-resolution neutron powder diffraction studies revealed that trivalent-cation (Bi, La, and Nd) substitution induces Sr vacancies for the requirement of charge neutrality. Polarization measurements of dense ceramics indicated that Bi substitution led to an increase in 2Pr and the 2Pr value for Sr0.73Bi2.18Ta2O9 was twice as large as that of SBT. Structural refinements revealed that Bi substitution enhances spontaneous polarization (Ps) and the improvement of Ps is responsible for the larger 2Pr observed. La substitution with Sr vacancies increased Pr slightly, but the 2Ec value (41 kV/cm) of La0.33Sr0.5Bi2Ta2O9 was much smaller than that for SBT (57 kV/cm). Nd-substituted SBT showed almost the same Pr of La–SBT, while a high 2Ec (125 kV/cm) was attained for Nd0.33Sr0.5Bi2Ta2O9. It is suggested that the higher Ec found in Nd–SBT is attributed to oxide vacancies produced by the substitution of a very small amount of Nd at the Ta site. Defect engineering is expected to open the way for the design of the polarization properties in SBT.

Room-Temperature Magnetic Refrigerate System Gadolinium-Terbium-Neodynium

A system of magnetic materials suited for a room temperature magneto-refrigeration, Gd-Tb-Nd, has been investigated. Samples were melted in an argon-protected high-frequency magnetic induction furnace. Magnetization curves were measured with a vibrating-sample magnetometer, in order to obtain the magnetic entropy change. Experimental results show that the Curie temperature (T c ) of the present system is near room temperature and decreases as the Tb and Nd contents increase. By addition of a small amount of Nd, the magnetic entropy change is comparable with that of Gd-Tb, and the transition temperature changes greatly. Therefore Nd can be used as a working temperature regulator. The Gd-Tb-Nd system is a prospect for realizing a large-scale room-temperature refrigeration in low magnetic fields.

Substitution effect on ferromagnetism inLa4Ba2Cu2O10

The magnetic properties of $({\mathrm{La}}_{1\ensuremath{-}x}{R}_{x}{)}_{4}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{2}{\mathrm{O}}_{10}$ were studied for $R=\mathrm{Nd},\mathrm{Sm},\mathrm{Gd},\mathrm{and}\mathrm{Eu},$ of which the end material, ${\mathrm{La}}_{4}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{2}{\mathrm{O}}_{10},$ is known as a rather exceptional ferromagnet among the known copper-oxide insulators. It was found that the average ionic radius of the elements at the La site r determines the solubility limit of R elements. When r is larger than $\ensuremath{\sim}1.11\mathrm{\AA{}}\mathrm{},$ the compound has the ${\mathrm{La}}_{4}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{2}{\mathrm{O}}_{10}$-type structure, while for smaller r, the ${\mathrm{Y}}_{2}{\mathrm{BaCuO}}_{5}$ type structure is formed. The magnetic behavior of the compounds depended on the R element; even a rather small amount of Nd altered the ferromagnetic ground state to an antiferromagnetic one, with a possible spin-glass state in between. For $R=\mathrm{Sm}$ and Gd, the experimental results suggest a similar change of ferromagnetism to antiferromagnetism, but a ferrimagnetlike behavior was observed for intermediate compositions. On the other hand, ferromagnetism resided up to the solubility limit for $R=\mathrm{Eu}.$ The application of high pressure up to 8.0 GPa hardly affected the magnetism of ${\mathrm{La}}_{4}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{2}{\mathrm{O}}_{10}.$ This result, as well as the results of Rietveld analyses of R-substituted ${\mathrm{La}}_{4}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{2}{\mathrm{O}}_{10},$ indicate that the reduction of ferromagnetism with the increase in x is not attributable to the structural change induced by the substitution, the chemical pressure effect.

Processing and grain boundary effects in Nd/sub 1-x/Ba/sub 2-x/Cu/sub 3/O/sub 7+d/ superconductors

Nd/sub 1-x/Ba/sub 2-x/Cu/sub 3/O/sub 7+d/ samples have been prepared with sharp superconducting transitions, with careful attention given to the details of sample preparation. Two causes for broad samples have been observed. The first is sample inhomogeneity, which is more difficult to eliminate than in the YBa/sub 2/Cu/sub 3/O/sub 7/ case, and the second appears to be associated with site disorder within a homogeneous sample. Very reasonable intragranular critical currents have been obtained in a sample with a small amount of Nd substituted on the Ba sites, but it is not clear if the Nd plays a direct role in flux pinning. Intergranular critical currents are still quite low due to the large grain size in the high-temperature-processed material and the Nd-deficient layer on the grain boundaries.

Auger spectroscopy of rare earth-transition metal-boron magnets in relation to the mechanism of coercivity

Magnets of composition Nd/sub 15/Fe/sub 78/B/sub 7/ were examined by SEM (scanning electron microscopy) and Auger spectroscopy. The sample was fractured in the ultra-high-vacuum chamber of the spectrometer, and examination of the fracture surfaces provided information which is taken to be representative of the internal structure and composition of Nd-Fe-B magnets. The grains were found to be coated with an Nd-rich film that was presumably generated by the high reactivity between oxygen and Nd. The technique provided information as to the changes occurring during postsintering. The two main effects are reduction in grain size by about a factor of two and the development of a more homogeneous (Nd-rich) film. Prior to postsintering, a small amount of Nd was observed on the grain surface. Afterward, the Nd content had risen sharply (a factor of three or more). The results are used to provide fresh insight into the mechanism of coercivity. The Nd-rich film is thought to be a magnetic dead layer which insulates the particles and makes the system behave as an assemblage of weakly interacting fine particles. Nucleation, which is a rare event, is isolated by the dead layer in the grain of origin, giving rise to the large observed coercivity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>