16454-60-7Relevant academic research and scientific papers
Photoluminescence studies on rare earth titanates prepared by self-propagating high temperature synthesis method
Joseph, Lyjo K.,Dayas,Damodar, Soniya,Krishnan, Bindu,Krishnankutty,Nampoori,Radhakrishnan
, (2008)
The laser-induced luminescence studies of the rare earth titanates (R2Ti2O7) (R = La, Nd and Gd) using 355 nm radiation from an Nd:YAG laser are presented. These samples with submicron or nanometer size are prepared by the
Rare earth tungsten bronzes: A new method of synthesis. Perspectives for their application as inert matrices for transmutation of long-life actinide elements
Bessonov,Fedosseev,Krupa,Shirokova,Budantseva
, p. 182 - 188 (2002)
A new method of synthesis of oxide tungsten bronzes containing lanthanide (Ln) Nd and Eu, based on thermal degradation of polyoxotungstate compounds, is proposed. The simplicity of the method allows to consider this class of compounds with chemical formula, LnxWO3, as potential inert target for incineration or transmutation of minor actinides, Am and Cm, in neutron reactors. Nd and Eu were used as analogues of transplutonium elements. Powder X-ray diffraction patterns of compounds synthesized reveal a cubic perovskite structure. The lanthanide content in bronzes was determined by optical spectroscopy analysis. The experimental density of the pressed bronze samples was estimated at 6.58 g cm-3, i.e., 89% of the crystallographic value. The thermal stability of the bronzes synthesized was checked up to 900°C in an inert atmosphere. Leaching tests were performed for europium bronzes in nitric acid solutions using luminescence technique.
Preparation of nanopowdered M1-x R x F2+x (M = Ca, Sr, Ba; R = Ce, Nd, Er, Yb) solid solutions
Kuznetsov,Yarotskaya,Fedorov,Voronov,Lavrishchev,Basiev,Osiko
, p. 315 - 320 (2007)
The synthesis procedure has been worked out, and nanopowders of fluoride solid solutions (ss) Ca1-x R x F2+x (R = Er, Yb), Sr1-x Nd x F2+x , and Ba1-x Ce x F2+x/
Spectroscopic properties of Nd3+ in MgAl2O 4 spinel nanocrystals
Dereń,Maleszka-Bagińska,G?uchowski,Ma?ecka
, p. 39 - 43 (2012)
Nd3+ doped MgAl2O4 spinel nanocrystals have been prepared by the sol-gel method. Their size decreases from 12 to 7 nm with increasing Nd3+ concentration from 0.1 to 5%, respectively. Some crystal field component
Moderate pressure synthesis of rare earth nickelate with metal-insulator transition using polymeric precursors
Napierala,Lepoittevin,Edely,Sauques,Giovanelli,Laffez,VanTedeloo
, p. 1663 - 1669 (2010)
Rare earth nickelates exhibit a reversible metal-semiconductor phase transition that is, in the infrared range, responsible for a thermo-optical contrast. The state of the art synthesis of these compounds usually requires high oxygen pressure to stabilize Ni in the oxidation state 3+. In this work, using polymeric precursor associated with moderate pressure annealing, we show that it is possible to obtain fully oxidized rare earth nickelate with metal-insulator transition. Using thermogravimetric analysis, X-ray diffraction and transmission electronic microscopy we compare different samples synthesized at different oxygen pressures and demonstrate their structural similarity. Thermo-optical properties were measured, in the infrared range, using reflectance measurements and confirmed the metal-insulator transition at 60 °C in both samples.TEM observations lead to the conclusion that the structure commonly obtained at 175 bar is perfectly observed in the 20 bar sample without major structural defects. The two samples exhibit a thermochromic behavior and thermo-optical properties of the two samples are equivalent.
Synergistic extraction and solution structures of ternary complexes of lanthanoids with 2-thenoyltrifluoroacetone and linear poly(oxyethylene) in 1,2-dichloroethane
Gagabe, Gene Frederick,Satoh, Yuta,Satoh, Keiichi,Sawada, Kiyoshi
, p. 2357 - 2364 (2007)
Synergistic extraction of thenoyltrifluoroacetone (tta) complexes of 14 trivalent lanthanoids (Ln3+) into 1,2-dichloroethane with linear poly(oxyethylene) compounds (POE) was investigated at 25.0°C, where the linear POE [HO-(CH2CH2O-)nR] are monodispersed DEOn (R = C12H25; n = 4, 6, and 8) and polydispersed TX-100 (R = octyl-phenyl; nave = 9.6). Equilibrium studies showed a 1:1 adduct complex with POE compound, Ln(tta)3 · (POE), formed in the organic phase. The adduct formation constant, βadd, increased as the ionic radius of lanthanoid increased for any kind of POE. The very high stability of the 18-crown-6 adducts is explained by the incorporation of Ln3+ ion into the cavity of the crown ether. Adduct formation constants of the POE having short ethylene oxide (EO) chain, such as DE04 and 12-crown-4, were fairly small; thus, it was estimated that those coordinate to the metal ion as a bidentate or tridentate ligand. Relatively large values of βadd of long chain POE (n ≥ 6) indicate the indirect outer-sphere interaction of the uncoordinated residual EO units with the metal ion. Adduct formation with linear POEs significantly reduced the difference in extraction constants among the lanthanoid ions. Therefore, this synergistic extraction system is advantageous for the separation of lanthanoid ions as a group from other metal ions.
The coupled TG-MS investigations of lanthanide(III) nitrate complexes with hexamethylenetetramine
Zalewicz,Trzesowska
, p. 525 - 534 (2004)
New transition metal compounds of the general formula Ln(NO 3)3·2[N4(CH2) 6]·nH2O, where Ln = La, Nd, Sm, Gd, Tb, Dy, Er, Lu, and n = 7-12, were obtained. The compounds and the gases evolve
Complexation thermodynamics of rare earth (III) with crown ethers. 31.Calorimetric titration of light lanthanoid (III) nitrates with dibenzo-18-crown-6 in acetonitrile
Liu, Yu,Han, Baohang,Zhang, Zhihui,Guo, Jihui,Chen, Yunti
, p. 1 - 6 (1998)
Calorimetric titrations have been performed in anhydrous acetonitrile at 25°C to give the complex stability constants (Ks) and the thermodynamic quantities for the complexation of light lanthanoid (III) nitrates (La-Gd) with 2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclooctadeca-2,11-diene (dibenzo-18-crown-6) (2). Data analyses, assuming 1 : 1 stoichiometry were successfully applied to all the light lanthanoid-crown ether combinations employed. Using the present and reported data, the complexation behaviors of (2) and 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) (1) are compared from the thermodynamic point of view. The rigid structure of (2), as compared with (1), gave the higher Ks for Nd3+ and Sm3+ among the light lanthanoid nitrates. The complex stability sequence as a function of reciprocal ionic diameter of lanthanoid showed a monotonically declining pattern for (1) except for a jump at Ce3+, and a characteristic peak profile at Nd3+ and Sm3+ for (2). Thermodynamically, the complexation of light lanthanoid nitrates with 18-crown-6 is mainly enthalpy-driven in acetonitrile, but the complexation with (2) is chiefly entropy-driven.
Effect of rare earth substitution on magnetic and structural properties of Co1-xREx Fe2O4 (RE: Nd, Eu) nanoparticles prepared via EDTA/EG assisted sol-gel synthesis
Avazpour,Shokrollahi,Toroghinejad,Zandi Khajeh
, p. 441 - 447 (2016)
Four groups of the series of rare earth (RE) substituted cobalt ferrite Co1-x REx Fe2 O4; x = 0-0.2 in steps of 0.05 and RE is Nd and Eu were prepared using the sol-gel method at annealing temperatures 550° C. The materials were characterized by powder X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM) and Fourier Transform Infrared spectroscopy (FTIR). The phase identification of the materials by XRD reveals the single-phase nature of the materials. The crystallite sizes of the materials were varied by altering the substitution content within the range of a minimum of 11 nm-31 nm. The magnetic parameters have been studied by using vibrating sample magnetometer (VSM). The saturation magnetization of the ferrite materials at room temperature decreases with the reduction of size. This has been attributed to increased surface to volume ratio and spin canting phenomena. The substituted rare-earth ions inhibit the grain growth of the materials in a systematic manner compared with that of the pure cobalt ferrite materials. There is an improvement in coercivities of the rare earth substituted cobalt ferrite especially for 5% Neodymium substituted cobalt ferrite with approximately 2 kOe coercive field. This is attributed to the contribution from the single ion anisotropy of the rare-earth ions present in the crystal lattice and the effects of a change in magnetic structures on the surface of the nanoparticles.
Synthesis of Ba4R3F17 (R stands for rare-earth elements) powders and transparent compacts on their base
Kuznetsov,Fedorov,Voronov,Samarina,Ermakov,Osiko
, p. 484 - 493 (2010)
Single-phase samples of Ba4R3F17 ? nH2O (R = La, Ce, Pr, Nd, Eu, Gd, Y, Er, or Yb; n = 2.5-3.2) were prepared by coprecipitation from nitrate solutions using hydrofluoric acid. The phases crystallize in a fluorite-type face-centered cubic lattice. The dried precipitates are transparent. Scanning electron and atomic-force microscopy and X-ray diffraction line broadening show a hierarchic structure in the samples: primary nanoparticles join into agglomerates with characteristic sizes of about 150-200 nm, these agglomerates being self-packed into parallel layers with a thickness on the order of 500 nm.
