13765-26-9Relevant articles and documents
The phase diagram of the system LiF-GdF3
Ranieri,Bressiani,Morato,Baldochi
, p. 95 - 98 (2004)
The phase diagram of the system LiF-GdF3 has been revised, using differential thermal analysis (DTA). We observed a eutectic reaction at 25mol% of GdF3 and 698°C and a peritectic reaction at 34mol% of GdF 3 and 755°C. We found indications for a GdF3 phase transformation from hexagonal to orthorhombic at 900°C. An identification of the formed phases was made by X-ray diffraction and SEM.
Variation in Eu3+ luminescence properties of GdF 3:Eu3+ nanophosphors depending on matrix GdF3 polytype
Zhang, Xiaoting,Hayakawa, Tomokatsu,Nogami, Masayuki,Ishikawa, Yukari
, p. 2076 - 2080 (2011)
Hexagonal and orthorhombic GdF3:Eu3+ nanophosphors separately synthesized at room temperature were well characterized by X-ray diffraction (XRD) analysis and photoluminescence excitation and emission spectral measurements. Hexagonal GdF3:Eu3+ nanophosphors intrinsically exhibited stronger Eu3+ luminescence intensity under ultraviolet excitation. The Rietveld fitting of well-defined XRD data elucidated that the interatomic distances between Gd3+ ions in the hexagonal structure were shorter than those in the orthorhombic structure and that most Eu ions in GdF3:Eu3+ occupy Gd sites. The stronger luminescence in the hexagonal structure was conclusively explained by the much more efficient energy transfer from Gd to Eu in the hexagonal structure than in the orthorhombic structure, as determined on the basis of the interatomic distance between Gd and Eu.
Comparison of different NaGdF4:Eu3+ synthesis routes and their influence on its structural and luminescent properties
Karbowiak, Miros?aw,Mech, Agnieszka,Bednarkiewicz, Artur,Str?k, Wies?aw,K?piński, Leszek
, p. 1008 - 1019 (2005)
Eu3+:NaGdF4 samples were obtained via co-precipitation in aqueous solution (CP), reversed micelle (RM) method, reaction between solid GdF3 and NaF solution (SR) as well as a solid-state reaction at high temperatures (SS). The synthesised materials were characterised using X-ray powder diffractometry, TEM microscopy, infrared spectroscopy and TGA analysis. For discussion of optical properties excitation and emission spectra were recorded and emission decay times were measured. The CP and RM methods allow to obtain powders with crystallite size of ～10 nm, which may be smoothly increased to about 1 μm during post-fabrication heat treatment. Differences in structural and especially in optical properties of phosphors prepared by different techniques are emphasised and applicability of wet-chemistry routes for synthesis of fluoride powders is argued.
Phase transitions and thermal properties of gadolinium trifluoride
Stankus,Khairulin,Lyapunov
, p. 30 - 33 (1999)
The temperature dependence of gadolinium trifluoride density in the solid and liquid states was determined by a gamma attenuation technique. Volume changes on solid-solid and liquid-liquid transitions were measured. The density and volume coefficient of thermal expansion of the liquid salt at the melting point are equal to 5609±25 kg m-3 and (16.2±0.5)×10-5 K-1, respectively. The relative density reduction on melting equals 16.7±0.15%. The polymorphic transformation from the low-temperature orthorhombic modification (a lattice of β-YF3 type) into the high-temperature hexagonal phase (LaF3 type) occurs with an increase of the density (about 2.1%). The peculiarities of the thermal expansion of the solid rare earth fluorides, undergoing phase transition β-YF3-type→LaF3-type, are discussed.
Lanthanide pentafluorophenolates. Synthesis, structure and luminescent properties
Maleev, Alexander A.,Fagin, Anatoly A.,Ilichev, Vasily A.,Lopatin, Mikhail A.,Konev, Alexey N.,Samsonov, Maksim A.,Fukin, Georgy K.,Bochkarev, Mikhail N.
, p. 126 - 132 (2013/11/19)
The pentafluorophenolates of lanthanides Ln(OC6F 5)3 (Ln = Nd (1), Tb (2), Er (3)) were prepared by the reactions of pentafluorophenol with appropriate silylamides Ln[N(SiMe 3)2]3 in benzene or toluene solution. The same reactions in ether or methanol medium afforded the solvated complexes Ln(OC 6F5)3(Et2O)3 (Ln = Nd (4), Eu (5), Tb (6), Er (7), Gd (8)) or Nd(OC6F5) 3(MeOH)3 (9), respectively. The phenanthroline complexes Ln(C6F5O)3(phen) (Ln = Pr (10), Nd (11), Er (12)), Ln(OC6F5)3(phen)2 (Ln = Sm (13), Tb (14), Ho (15), Ln(OC6F5)3(phen) 2(Et2O) (Ln = Eu (16), Yb (17)), and Ln(OC 6F5)3(phen)(Et2O)3 (Ln = Eu (18), Nd (19), Ce (20), Dy (21)), Ln(OC6F5) 3(phen)2(H2O) (Ln = Sm (22), Ho (23)), and Gd(OC6F5)3(phen)2(MeOH) (24) were obtained when the reactions were carried out in the presence of 1,10-phenanthroline. The complexes with pyridine Tb(OC6F 5)3(py)5 (25) and 2,2′-bipyridyl Ln(OC6F5)3(bpy)2 (Ln = Tb (26), Yb (27)) were synthesized similarly. Compounds 7, 22, 23, and 24 were characterized by X-ray analysis. The complexes Ln(OC6F5)3 decompose above 150 C in vacuum to give lanthanide fluorides and octofluorodibenzo-p-dioxine. Phenanthroline derivatives are stable up to 310 C. Luminescence spectra of all the obtained complexes in visible region contain a broad band of ligand-centered emission peaked at 405-415 nm. Spectra of samarium 13, europium 5, 16, 18 and terbium 14, 25, 26 derivatives display also the characteristic narrow bands of Sm3+, Eu3+ and Tb 3+ ions.
Preparation of REFeAsO1-xFx (R E=Sm and Gd) superconductors at a relatively low temperature
Cui,Chen,Cheng,Yang,Wang,Li,Zhao
, p. 449 - 452 (2011/07/07)
A series of the SmFeAsO1-xFx and GdFeAsO 1-xFx (x=0.05, 0.1, 0.15, 0.2, 0.25) samples have been prepared using nano-scaled ReF3 as the fluorine resource at a relatively low temperature. The samples have been sintered at 1100 and 1120 °C for SmFeAsO1-xFx and GdFeAsO1-xF x, respectively. These temperatures are at least 5060° lower than other previous reports. All of the so-prepared samples possess a tetragonal ZrCuSiAs-type structure. Dramatically supression of the lattice parameters and increase in Tc proved that this low temperature process was more effective to introduce fluorine into REFeAsO. Superconducting transition appeared at 39.5 K for SmFeAsO1-xFx with x=0.05 and at 22 K for GdFeAsO1-xFx with x=0.1. The highest Tc was detected to be 54 K in SmFeAsO0.8F0.2 and 40.2 K in GdFeAsO0.75F0.25. The use of the nano-scaled ReF3 compounds has improved the efficiency of the present low temperature method in synthesizing the fluorine-doped iron-based superconductors.
