Properties Of Nd Research Articles

Effect of calcination temperature on nanoparticle morphology and its consequence on optical properties of Nd:Y2O3 transparent ceramics

The morphological and size distribution change of Nd:Y2O3 nanoparticles due to calcination temperature influences the transparency of ceramic pellets.

Thermal and Mechanical Properties of Nd<sup>3+</sup>/Yb<sup>3+</sup> Co-Doped Titanate Glass with Upconversion Emissions

Thermal and Mechanical Properties of Nd<sup>3+</sup>/Yb<sup>3+</sup> Co-Doped Titanate Glass with Upconversion Emissions

Effect of composition deviation on the microstructure and luminescence properties of Nd:YAG ceramics

Non-stoichiometric compositions lead to microstructures different from that of stoichiometric Nd:YAG. Nanograins of excess Al2O3 remain inside the Nd:YAG grains in Al2O3-excess ceramics, while Y-rich compounds recrystallize at the Nd:YAG grain boundaries in Y2O3-excess ceramics.

Synthesis and Physical Properties of Nd:YVO4 Nanopowders prepared by a Chemical Method

In this paper, a simple chemical method is employed to synthesize Nd:YVO4 nanopowders without any special thermal and pressure conditions. To adjust the pH value of the solution, we used ammonia instead of sodium hydroxide. Experimental. Starting materials in this work were high-purity V2O5, Y2O3 and Nd2O3. First, 1.2 g of V2O5 was dissolved in hydrochloric acid. Then 1.5 g of Y2O3 and 0.1 g of Nd2O3 were dissolved in nitric acid to obtain a clear solution. The two solutions were mixed and ammonia was gradually added to this clear solution under vigorous stirring until its pH value reached 7–11. Ropp and Carroll [14] reported that the ionic form of vanadium was extremely sensitive to the pH of the solution. When the solution was strongly acidic, vanadium existed in the form of the VO 2+ ions. When the pH was elevated to 2, the V10O28 6– ions were observed; the increase in the pH of the solution to 5 and to 7–11 resulted in the V3O9 3– and VO4 3– vanadium ions respectively. Since the pH value in the present work was in the range of 7 to 11, the following reactions might occur: 3OH – + V3O9 3– �: 3VO 4 3– + 3H + ,

Up- and Downconversion Luminescence Properties of Nd3+Ions Doped in Bi2O3–BaO–B2O3Glass System

Physical, optical, and luminescence properties of Nd3+ions in bismuth barium borate glass system were studied. The glasses prepared by a melt quenching method were doped at various Nd2O3concentrations in compositions (40-x)B2O3 : 40Bi2O3 : 20BaO : xNd2O3(wherex= 0.00, 0.50, 1.00, 1.50, 2.00, and 2.50 in mol%). Luminescence properties of the glasses were studied under two excitations of 585 and 750 nm for downconversion. From both excitations, the results show emission bands in NIR region corresponding to the transitions between4F3/2 → 4I9/2(900 nm),4F3/2 → 4I11/2(1,060 nm), and4F3/2 → 4I13/2(1,345 nm). The luminescence intensity obtained with 585 nm excitation was stronger than 750 nm, with the strongest NIR emission at 1,060 nm. The upconversion emission spectrum exhibits strong fluorescence bands in the UV region at 394 nm (λex=591 nm). The processes are associated with excited state absorption (ESA) from4F3/2level to4D3/2level and it is the radiative decay from the4D3/2to ground levels (4D3/2 → 4I13/2) which are responsible for the emission at 394 nm.

掺钕TeO2-Al2O3-Cs2O玻璃的Judd-Ofelt理论分析与光谱特性

掺钕TeO₂-Al₂O₃-Cs₂O玻璃的Judd-Ofelt理论分析与光谱特性

Dependence of magnetic, phase-transformation and microstructural characteristics on the Cu content of Nd–Fe–B sintered magnet

We have investigated the changes in the magnetic, phase-transformation and microstructural properties of Nd–Fe–B sintered magnets as a function of Cu content (0.2–0.5at.%). The coercivity decreased (28.7→27.1kOe) with increasing Cu content without changing the remanence of the magnets under the normal post-sintering annealing (PSA) conditions. Phase-transformation temperature changes of the magnet were observed as the Cu content of the magnet was increased. In the 0.2at.% Cu magnet, the triple junction phase (TJP) and grain boundary phase (GBP), composed of the Cu-enriched C-Nd2O3 phase, were formed. However, in the 0.5at.% Cu magnet, the TJP and GBP were composed of the h-Nd2O3 phase. By considering the dependence of Cu content on the phase transformation, we have modified the 1st-PSA temperature to recover the coercivity. Through our newly established PSA conditions, the TJP and GBP in the 0.5at.% Cu magnet were formed as the C-Nd2O3 phase. As a result, the coercivity of the magnet was noticeably enhanced (27.1→29.4kOe). The reasons for the coercivity deterioration in the high-Cu-content magnet were clarified. The detailed mechanism of the microstructural and magnetic property improvements induced by the modified 1st-PSA condition is discussed. The critical role of Cu in the microstructural changes of Nd-rich TJP and GBP during the PSA is also analyzed based on these results.

Effect of DyF3 on the corrosion behavior of hot‐pressed Nd–Fe–B permanent magnets

The grain boundary diffusion process (GBDP) with DyF3 is a promising method to obtain excellent magnetic properties in Nd–Fe–B permanent magnets. Compared to conventionally prepared (Dy,Nd)–Fe–B magnets the overall content of the precious heavy rare earth Dy is reduced. Thus, the GBDP with DyF3 is highly attractive to cut down costs and save resources. However, it is not well known how the addition of DyF3 affects the corrosion resistance of Nd–Fe–B permanent magnets. In this work, the anodic polarization behavior of hot‐pressed Nd–Fe–B magnets with and without DyF3 additions was investigated in electrolytes of different pH values. The results were compared with measurements on a commercially sintered Nd–Fe–B permanent magnet. In the polarization studies the only observed significant impact of DyF3 additions is an increased passive current density in alkaline media. The pitting susceptibility in NaOH solutions containing chloride ions is not affected by DyF3. Also in contrast to expectations, first free corrosion studies indicated no significant impact of the DyF3 additions on the dissolution rate.

Highly transparent Nd:Lu2O3 ceramics obtained by coupling slip-casting and spark plasma sintering

A ceramic process coupling slip-casting of nanopowder suspensions and spark plasma sintering was used to prepare highly transparent Nd:Lu 2 O 3 ceramic without any sintering aids. The influence of shaping by slip-casting on residual microstructural defects after sintering was investigated. Green compacts of nanopowders with homogeneous and submicron pore size promotes the elaboration of highly transparent ceramics with near-to-theoretical inline transmittance of 81.3% at 1060 nm. Spectroscopic properties of Nd:Lu 2 O 3 ceramics were investigated at room temperature and 77 K.

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).

Fluorescence and radiative properties of Nd3+ ions doped zinc bismuth silicate glasses

Abstract Glasses having composition 20ZnO⋅ x SiO 2 ⋅(79.5− x )Bi 2 O 3 ⋅0.5Nd 2 O 3 with x varying from 10 to 50 mol% have been synthesized. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. Optical absorption and fluorescence spectra were measured at ambient temperature. This paper reports on different physical and absorption spectral properties of Nd 3+ doped zinc bismuth silicate glasses with varying content of Bi 2 O 3 to understand its influences on hypersensitive band intensities. From the recorded absorption spectra, Judd–Ofelt intensity parameters Ω λ = ( λ = 2, 4, 6) have been evaluated with their quality factors and are used to compute the radiative properties of Nd 3+ glasses. The calculated Judd–Ofelt parameters are found to decreasing with decrease in Bi 2 O 3 content in the glass which may be due to the decrease in Nd–O bond covalency. From these intensity parameters various radiative properties like spontaneous emission probability ( A rad ), radiative life time ( τ r ), fluorescence branching ratio ( β r ) and stimulated emission cross-section ( σ ) for various emission bands have been calculated. The stimulated emission cross-section of fluorescence transition 4 F 3/2 → 4 I 11/2 have high values and varies from 15.19 × 10 −20 cm 2 to 5.73 × 10 −20 cm 2 with Bi 2 O 3 content in the host glass. The results point out this glass system as good candidate to be used in the development of photonics devices operating in the near infrared spectral range. Further, the FTIR results reveal that the glasses have BiO 6 , SiO 4 and non-bridging oxygen as local structure.

Improvement of infrared laser properties of Nd:CaF_2 crystals via codoping with Y^3+ and Lu^3+ buffer ions

We demonstrate that codoping Nd:CaF2 single crystals with Y3+ and Lu3+ nonoptically active ions significantly improves their absorption, emission, and fluorescence lifetime properties and their laser performance. The spectral profiles get smoother and wider, wider than that found with standard Nd:glasses; the quantum yields increase; and efficient laser operation is obtained around 1.055 μm.

Physical, electrical, transport and magnetic properties of Nd(Ba,Nd)2.1Cu3O7−δ system

In this study, the superconducting Nd(Ba,Nd)2.1Cu3O7−δ system has been prepared using conventional solid-state reaction technique. Transport properties including structural/microstructural evolution, electrical, magnetic and critical current density properties were investigated. After high temperature heat treatments at over 1,000 °C, large and strongly connected grains were obtained but weakly connected and small in size granular formation were obtained for the low temperature heat treated samples at around 900 °C. The best T c and T 0 values were obtained as 93 and 89 K respectively for the sample prepared at 1,020 °C for 24 h, which is very close to peritectic temperature of YBCO material. Magnetization of the sample heat treated at 1,020 °C was investigated in detail. The magnetization hysteresis loops are expounded to be the product of Nd-123 grains and unscreened Nd3+ ions within intergranular boundaries and vortex cores. The peak effect on the magnetization curves was described by the extended critical state model. Temperature dependencies of the irreversibility field, the peak field and the full penetration field correlate and there is scaling behavior of the pinning force as well. Thermoelectric power data was analyzed by “Modified two band model with linear T-term for superconductors”. Temperature dependence of thermal conductivity of the samples showed small peak with broad maximum just below the T c value. Thermal conductivity of samples prepared was calculated by using “The Modified Callaway Model and Wiedermann–Franz law” and results obtained discussed.

Energy transfer properties of Nd3+→Yb3+ in Nd:Yb:LiNbO3 crystals

Abstract Nd:Yb:LiNbO 3 nonlinear laser crystal is a candidate for NIR laser around 1000 nm and self-frequency-doubling laser around 500 nm, with mature pump technique using ~808-nm diode laser, via Nd 3+ absorption and efficient Nd 3+ →Yb 3+ energy transfer. High-quality Nd:Yb:LiNbO 3 crystals were grown by Czochralski method, and the main spectroscopic properties of Nd 3+ →Yb 3+ (Nd 3+ : 4 F 3/2 +Yb 3+ : 2 F 7/2 →Nd 3+ : 4 I 9/2 +Yb 3+ : 2 F 5/2 ) energy transfer in LiNbO 3 crystals were studied systemically based on emission spectra and luminescence decay curves. Energy transfer efficiency as high as 86% was obtained in a Nd 3+ (0.8 mol%) and Yb 3+ (2.0 mol%) codoped sample, so Nd:Yb:LiNbO 3 laser with a higher efficiency than that of Nd:LiNbO 3 laser might be achieved under identical pump conditions.

Electrochemical study of the properties of Nd(III) and Nd(II) ions in molten LiCl-KCl-CsCl eutectic and individual CsCl

The electrochemical behavior of NdCl3 solutions in eutectic LiCl-KCl-CsCl and individual CsCl melts was studied on an inert molybdenum electrode at temperatures in the range 573–943 K. Cyclic and differential pulse voltammetry and potentiometry at zero current and the electromotive forces method were used. The cathode reduction of Nd(III) ions to the metal was found to occur as a sequence of two stages. The formed Nd(II) ions were unstable above 798 K and underwent disproportionation 3Nd(II) ⇔ 2Nd(III) + Nd(m) in the salt melts. The conventional standard redox potential of the Nd(III)/Nd(II) pair in a eutectic LiCl-KCl-CsCl melt was measured over a wide temperature range. The main thermodynamic characteristics of the reaction NdCl2(m) + 1/2Cl2(g) ⇔ NdCl3(m) were determined.

Effect of Sm substitution on microwave dielectric properties of Nd(Mg0.5Sn0.5)O3 ceramics

The microwave dielectric properties of Nd(1−x)Smx(Mg0.5Sn0.5)O3 ceramics were examined with a view to their exploitation in mobile communication. The Nd(1−x)Smx(Mg0.5Sn0.5)O3 ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the Nd0.98Sm0.02(Mg0.5Sn0.5)O3 ceramics revealed no significant variation of phase with sintering temperatures. A density of 6.87 g/cm3, a dielectric constant (e r ) of 19.2, a quality factor (Q × f) of 104,300 GHz, and a temperature coefficient of resonant frequency (τ f ) of −57 ppm/°C were obtained for Nd0.98Sm0.02(Mg0.5Sn0.5)O3 ceramics that were sintered at 1,550 °C for 4 h.

Enhancing the microwave dielectric properties of Nd (Mg0.5Sn0.5)O3 ceramics by substituting Nd3+ with Ca2+

The microwave dielectric properties of Nd(1−2x/3)Cax(Mg0.5Sn0.5)O3 ceramics were examined to evaluate their exploitation for mobile communication. Nd(1−2x/3)Cax(Mg0.5Sn0.5)O3 ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the Nd2.9/3Ca0.05(Mg0.5Sn0.5)O3 ceramics revealed no significant variation of phase with the sintering temperature. Nd2.9/3Ca0.05(Mg0.5Sn0.5)O3 ceramics that were sintered at 1,550 °C for 4 h had the following properties: a density of 6.86 g/cm3, a dielectric constant (er) of 19.3, a quality factor (Q × f) of 99,000 GHz, and a temperature coefficient of resonant frequency (τf) of −65 ppm/°C.

Improvement of optical properties of Nd:YAG transparent ceramics by post-annealing and post hot isostatic pressing

The Nd:YAG transparent ceramics were fabricated by vacuum sintering. The Nd:YAG samples were annealed at 1450°C for 20h in air and followed by hot isostatic pressing (HIP) at 1700°C for 2h in 200MPa Ar and then re-annealed at 1250–1450°C for 10h in air. The experimental results showed that the optical properties of Nd:YAG samples varied markedly with different post treatments. After air annealing at 1450°C for 20h and HIP at 1700°C for 2h under 200MPa of Ar and then air re-annealing at 1250°C for 10h, the transmittances of the samples increased from 51.2% to 77.2% (at 400nm) and 78.4% to 83.6% (at 1064nm), respectively. The annealing and HIP are effective post treatments to reduce oxygen vacancies and intergranular pores respectively in Nd:YAG transparent ceramics.

GRAIN TEXTURE, Nd CONTENT AND PROCESSING CONDITION EFFECTS ON MAGNETIC PROPERTIES OF NdFeB COMPOSITE MAGNETS

The effects of grain texture, Nd content, processing conditions on magnetic properties and behavior of NdFeB nanocomposite magnet were investigated. The results demonstrate that mechanically activated disproportionation and desorption–recombination combined with plastic deformation process (M-HDDR & D) is an effective way to produce anisotropic NdFeB -type magnet. Magnetic anisotropy significantly enhances the magnetic properties of Nd 16 Fe 76 B 8 nanocomposite magnet, with the intrinsic coercivity (H ci ), magnetic induction (Br), and the energy product (BH) max achieving 0.88 T, 676.8 kA/m, and 135.2 kJ/m3, respectively. Decrease in Nd content improves the remanence but deteriorates the coercivity of NdFeB ternary composites. A low annealing temperature or short annealing time leads to an incomplete recombination, while a high temperature or long annealing time may result in grain overgrowth, and the optimum processing condition is found to be 780°C × 30 min. Pinning mechanism dominates in the magnetic hardening mechanism of Nd 16 Fe 76 B 8 composites prepared by both complete and incomplete recombination process, and particularly reversal nucleation process is also responsible for the latter case.

Continuous-wave Nd : GYSGG laser properties in 1.3 and 1.4 µm regions based on 4F3/2 to 4I13/2 transition

Continuous-wave laser properties of Nd : GYSGG crystal based on the transition from 4F3/2 to 4I13/2 are investigated. With different output couplers, single or multiple wavelength lasers operating at 1321, 1336, 1404 and 1424 nm are obtained, which provide new options in these wavelength bands. In the 1.3 µm region, the maximum output power is 2.5 W, corresponding to the conversion efficiency of 18.5%. In the 1.4 µm region, the maximum output power at 1424 nm is 707 mW, corresponding to the conversion efficiency of 6.8%. The output power and conversion efficiency can be improved with better anti-reflection coatings for the laser crystal.