Dy2O3 Nanoparticles Research Articles

Manufacture and Characterization of Dy2 O3 Nanoparticles via X-Ray Diffraction, TEM and Photoluminescence

In this research, Dysprosium Oxide (Dysprosia) nanoparticles with the composition, Dy 2 O 3 , were prepared by using the combustion method. The precursor sol was obtained from Dysprosium Nitrate and Glycine was used as the fuel. The molar ratio of cation/glycine = 1.5 was used to prepare very fine powder of dysprosium oxide. The innovative aspect of this method is the preparation of Dy 2 O 3 nanoparticles without applying calcination temperature. To study the effect of the heating and annealing on the structural and optical properties of dysprosia, three different calcination temperatures, 450 °, 550° and 650°C were applied on the initial product (no-calcined sample). Transmission Electron Microscopy (TEM) and X–Ray Diffraction (XRD) were used for structural characterization and Photo Luminescence (PL) was used for studying optical properties of the samples. XRD patterns show the ideal cubic structure for all samples. The crystallite sizes were estimated from the broadening of XRD peaks, using Scherrer’s formula. XRD estimated the crystallite sizes from 24 nm for no-calcined sample to 28 nm for the calcined sample at 650°C. TEM shows the sizes of the particles produced by this method ranged from 5 nm to 100 nm. The samples also exhibited room temperature PL, having a strong emission in the visible region. The band gap of the samples was measured by PL results.

Room Temperature Synthesis and Properties of Pure and Gadolinium Doped Dy<sub>2</sub>O<sub>3</sub> Nanoparticles

Pure and gadolinium doped Dy2O3nanoparticles were prepared by a convenient, wet chemical synthesis route and the particles were subjected to thermal, structural, morphological and optical property studies. The influence of gadolinium on particle size, lattice parameter and band gap energies were investigated. Structural and optical properties of the particles elucidated that the Gd3+ions have substituted the Dy3+ions without changing the cubic structure of Dy2O3. The optical property studies of Gd:Dy2O3nanoparticles showed enhanced optical absorption in UV region with respect to pure sample. The samples also exhibited room temperature PL, having a strong emission in the visible region.

Synthesis of Hollow SiO2 Nanoparticles from Dy2O3@SiO2 Core–Shell Nanocomposites via a Recyclable Sonochemical Method

Hollow silica nanoparticles were prepared from Dy2O3@SiO2 core–shell nanocomposites, for the first time, by a simple ultrasonic assisted sol–gel method. The Dy2O3@SiO2 core–shell nanocomposites were prepared by the deposition of a SiO2 layer onto the surface of Dy2O3 nanoparticles using a three-step coating process. The hollow SiO2 nanostructures were obtained by selective removal of the Dy2O3 cores. The structure, morphology and composition of the products were determined by the techniques of X-ray diffraction, Fourier transfom infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results indicated that hollow SiO2 nanostructures were sphere-like shape with the average size of 20 nm and had an amorphous crystal structure. The important advantage of this process is the recyclability of the Dy2O3 nanoparticles as the starting material of the reaction.

Wet chemical synthesis and characterization of pure and cerium doped Dy2O3 nanoparticles

Pure and cerium doped Dy2O3 nanoparticles were prepared by wet chemical synthesis route. The particles were subjected to thermal, structural, morphological and optical property studies. The calcination temperature was chosen based on the decomposition of the samples revealed by TG studies. EDS and FTIR results confirmed the presence of cerium in the Dy2O3 system. The particle size calculated from Williamson-Hall plot was consistent with TEM results. The effect of cerium as a dopant on the UV–vis absorption and photoluminescence intensity has been studied. XRD and PL analyses demonstrate that the cerium ions uniformly substitute dysprosium sites in Dy2O3 lattice and hence influence the optical properties.

Synthesis and photoluminescence properties of HMT passivated Dy2O3 nanoparticles

Dy2O3 nanoparticles were synthesized at room temperature through soft chemical route using dysprosium acetate hexahydrate and hexamethylenetetramine as starting materials. As-synthesized Dy2O3 nanoparticles were calcined up to 600°C and the samples were subjected to various characterizations. The decomposition course of as-prepared particles and the formation process of Dy2O3 were studied by TG/DTA. The cubic bixbyite phase formation of Dy2O3 nanoparticles was confirmed by XRD results. The particle size and morphology were investigated by TEM. The composition and surface passivation were confirmed by EDS and FTIR studies, respectively. The possible formation mechanism has been discussed based on the experimental results. Bandgap of the material was estimated from the UV–vis absorption spectra. A blue-shift was observed in the absorbance as a result of quantum confinement effect, which was supported by PL spectra.

Tuning of the Size of Dy2O3 Nanoparticles for Optimal Performance as an MRI Contrast Agent

The transverse 1H relaxivities of aqueous colloidal solutions of dextran coated Dy2O3 nanoparticles of different sizes were investigated at magnetic field strengths (B) between 7 and 17.6 T. The particle size with the maximum relaxivity (r2) appears to vary between 70 nm at 7 T (r2 approximately = 190 s(-1) mM(-1)) and 60 nm at 17.6 T (r2 approximately = 675 s(-1) mM(-1)). A small difference between r2 and r2* was observed, which was ascribed to the effect of the dextran coating. The value of r2 is proportional to B2 up to 12 T after which it saturates. Independent magnetization measurements on these particles at room temperature at magnetic field strengths up to 30 T, however, show a typical paramagnetic behavior with a magnetization of the particle that is proportional to the field strength. The saturation in the curve of r2 as a function of B2 was tentatively explained by the presence of an extremely fast relaxing component of the signal at high field strengths, which is not observable on the NMR time scale. The results of this study can be exploited for the rational design of MRI contrast agents, based on lanthanide oxide particles, with high efficiencies at magnetic field strengths of more than 1.5 T.

Minute pinning and doping additions for strong, 20K, in-field critical current improvement in MgB2

Minute additions of a combination of Dy2O3 and B4C have been used to enhance both pinning and upper critical field in MgB2. A delicate balance of Dy2O3 and B4C additions is required to improve properties. The Dy2O3 nanoparticles react with B to form 10–15nm DyB4 nanoparticles, while B4C supplies carbon into the MgB2 crystal lattice and increases the upper critical field. The optimum level of Dy2O3 and B4C additions is ∼0.5wt% of Dy2O3 and 0.04wt% of B4C, yielding a Jc (20K) of 105Acm−2 at 2.7T.

Enhanced in-field critical currents of YBCO second-generation (2G) wire by Dyadditions

The addition of dysprosium oxide nanoparticles is shown to improve thecritical current in perpendicular magnetic fields for second-generation (2G)wire formed by metal–organic deposition (MOD). Typical enhancements inJc arefrom 0.17 MA cm−2 toover 0.33 MA cm−2 at77 K and Bperp = 1.5 T. TEM analysis shows that we are introducing(Y,Dy)2O3 nanoparticles with dimensions of 10–50 nm. A simple theoretical analysis shows that themaximum pinning effect for additions is expected at excess concentrations of approximately 70%DyO1.5,i.e. for YBa2Cu3O7−δ+0.7DyO1.5 if the added nanoparticles are randomly dispersed and a strong pinning model is valid. Aninteresting feature is that the critical current in parallel field is reduced in these samples.We present evidence that shows this may be due to reduced planar defects in theYBCO.