- Study of the thermal properties of Pr(III) precursors and their implementation in the MOCVD growth of praseodymium oxide films
-
A praseodymium adduct, Pr(hfa)3·diglyme [(H-hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentandione, diglyme = CH3O(CH 2CH2O)2CH3)] has been synthesized. It has been applied as a Pr source for the metallorganic chemical vapor deposition (MOCVD) of praseodymium containing films on silicon substrate and compared with Pr(tmhd)3 [(H-tmhd = 2,2,6,6-tetramethyl-3,S- heptandione)] precursor. Physical and thermal properties of both Pr(hfa) 3·diglyme and Pr(tmhd)3 precursors have been fully analyzed and their efficacy as MOCVD precursors for the growth of praseodymium oxide films have been fully tested. Depending on the oxygen partial pressure (PO2), different praseodymium oxide phases have been obtained.
- Lo Nigro, Raffaella,Toro, Roberta G.,Malandrino, Graziella,Fragala, Ignazio L.,Rossi, Patrizia,Dapporto, Paolo
-
-
Read Online
- Crystal structure, electronic structure, and luminescence of Cs 2KYF6:Pr3+
-
The crystal structure, electronic states and VUV spectroscopic behaviour of Cs2KYF6 doped with Pr3+ ions have been investigated both by experimental and theoretical methods. Cs 2KYF6 (Fm3m, Z = 4, a = 945.5(3) pm, R1all = 0.0297) crystallizes with the cubic elpasolite type of structure. The local relaxation of the activator ions in the host lattices has been calculated by the projector augmented wave method (computer code VASP). The electronic states have been calculated using a spin density functional procedure based on the atomic sphere approximation (computer code ASW). VUV spectroscopic measurements show fast 4f1 5d1 → 4f2 emission of nanosecond duration as well as slow 4f2 → 4f2 emission depending on the excitation energy which indicates the occupation of different sites in the host lattice. This assumption was verified by a recently developed quantum mechanical method. The combination of the experimental and the theoretical results show that the Pr3+ ions are occupying three different sites, namely the Y3+ and the Cs+ site as well as the K+ site.
- Schiffbauer, Daniel,Wickleder, Claudia,Meyer, Gerd,Kirm, Marco,Stephan, Michael,Schmidt, Peter C.
-
-
Read Online
- The differences in solid state structures of C,N-chelated nbutyltin(IV) fluorides
-
The solid state structures of products of fluorination of LCNnBuSnCl2 (where LCN is 2-[(CH3)2NCH2]C6H4 -) by different methods are reported. The reaction of 3 equiv. o
- ?vec, Petr,Padělková, Zdeňka,?erno?ek, Zdeněk,Proft, Frank De,R??i?ka, Ale?
-
-
Read Online
- Infrared spectra and quantum chemical calculations of the bridge-bonded HC(F)LnF2 (Ln = La-Lu) complexes
-
Lanthanide metal atoms, produced by laser ablation, were condensed with CHF3 (CDF3) in excess argon or neon at 4 K, and new infrared absorptions are assigned to the oxidative addition product fluoromethylene lanthanide difluoride complex on the basis of deuterium substitution and density functional theory frequency calculations. Two dominant bands in the 500 cm-1 region are identified as metal-fluorine stretching modes. A band in the mid-600 cm-1 region is diagnostic for the unusual fluorine bridge bond C-(F)-Ln. Our calculations show that most of the bridged HC(F)LnF2 structures are 3-6 kcal/mol lower in energy than the open CHF-LnF2 structures, which is in contrast to the open structures observed for the corresponding CH2-LnF2 methylene lanthanide difluorides. Argon-to-neon matrix shifts are 15-16 cm -1 to the blue for stretching of the almost purely ionic Ln-F bonds, as expected, but 10 cm-1 to the red for the bridge C-(F)-Ln stretching mode, which arises because Ar binds more strongly to the electropositive Ln center, decreasing the bridge bonding, and thus allowing a higher C-F stretching frequency.
- Gong, Yu,Wang, Xuefeng,Andrews, Lester,Chen, Mingyang,Dixon, David A.
-
p. 4443 - 4452
(2011/10/10)
-
- The versatility of solid-state metathesis reactions: From rare earth fluorides to carboiimides
-
The new carbodiimide compounds LaF(CN2) and LiPr 2F3(CN2)2 were obtained as crystalline powders by solid-state metathesis reactions from 1:1 molar ratios of REF3 (RE = rare earth) and Lisu
- Unverfehrt, Leonid,Glaser, Jochen,Stroebele, Markus,Tragl, Sonja,Gibson, Katharina,Meyer, H.-Juergen
-
p. 479 - 483
(2009/06/17)
-
- Branched NaYF4 nanocrystals with luminescent properties
-
In this article, branched NaYF4 nanocrystals have been successfully synthesized via a simple hydrothermal method. On the basis of the analysis of HRTEM and TEM images, the growth modes of the branched structure and further branching behavior have been proposed. The up- and down-conversion luminescence of branched NaYF4:Er3+/Yb3+ and NaYF4:Eu3+ have been characterized. Multiarmed NaYF 4 phosphors can be introduced into polystyrene to form composite luminescent polymers because of its special geometrical shape. In conclusion, the luminescent branched particles should be of wide potential application as building blocks in the future nanoscience and nanotechnology.
- Liang, Xin,Wang, Xun,Zhuang, Jing,Peng, Qing,Li, Yadong
-
p. 6050 - 6055
(2008/10/09)
-
- Controlled hydrothermal growth and up-conversion emission of NaLnF 4 (Ln = Y, Dy-Yb)
-
The controlled hydrothermal preparation of NaYF4 as both cubic and hexagonal phase types with specific associated morphologies, nanospheres and microtubes, respectively, has been achieved in the absence of organic solvents. The hexagonal NaYF4 compound can be prepared in novel microtubular form and directly co-doped with Yb3+/Er3+ ions. When excited by infrared light of 980 nm, these hexagonal NaYF4 microtubes display strong green up-conversion emission, which was much more intense than that of cubic NaYF4 or hexagonal NaYF4 nanoparticles. Other related hexagonal-prismatic microtubes of NaLnF4 (Ln = Dy-Yb) were also synthesized. A growth mechanism for the microtubes is proposed. In general, the diameter of the hexagonal NaLnF4 microtubes is strongly dependent on the Ln3+ size and increases as the rare-earth ionic radius decreases.
- Zhuang, Jianle,Liang, Lifang,Sung, Herman H. Y.,Yang, Xianfeng,Wu, Mingmei,Williams, Ian D.,Feng, Shouhua,Su, Qiang
-
p. 5404 - 5410
(2008/10/09)
-
- Solubility of YF3, CeF3, PrF3, NdF 3, and DyF3 in solutions containing sulfuric and phosphoric acids
-
The solubility of YF3, CeF3, PrF3, NdF3, and DyF3 in solutions containing 0-4.496% mol/L (0-35 wt %) of H2SO4 and 0-27.6 g/L of H 3PO4 (0-20 g/L of P2
- Lokshin,Tareeva
-
p. 1830 - 1834
(2008/10/09)
-
- Hydrothermal synthesis of rare-earth fluoride nanocrystals
-
In this paper, a hydrothermal synthetic route has been developed to prepare a class of rare-earth fluoride nanocrystals, which have shown gradual changes in growth modes with decreasing ionic radii and may serve as a model system for studying the underlying principle in the controlled growth of rare-earth nanocrystals. Furthermore, we demonstrate the functionalization of these nanocrystals by means of doping, which have shown visible-to-the-naked-eye green up-conversion emissions and may find application in biological labeling fields.
- Wang, Xun,Zhuang, Jing,Peng, Qing,Li, Yadong
-
p. 6661 - 6665
(2008/10/09)
-
- Thermochemical studies on the lanthanoid complexes of trifluoroacetic acid
-
The thermal decomposition of the lanthanoid complexes of trifluoroacetic acid (Ln(CF3COO)3·3H2O; Ln = La-Lu) was studied by TG and DTA methods. The Ln(CF3COO) 3·3H2O complexes decompose in several stages; first dehydrate to the anhydrous state, then followed by decomposition of the anhydrous salt to a stable product of LnF3. From the endothermic and exothermic data of Ln(CF3COO)3·3H2O complexes, pyrolysis behavior of the complexes is classified into three groups: (1) La-Pr salts; (2) Nd-Gd salts; (3) Tb-Lu salts. It has been shown that all the final decomposition products were found to result in the formation of LnF3.
- Yoshimura,Ohara
-
p. 573 - 576
(2008/10/09)
-
- Synthesis and characterization of ternary NH4Ln 2F7 (Ln = Y, Ho, Er, Tm, Yb, Lu) nanocages
-
In this paper, a new class of NH4Ln2F7 (Ln = Y, Ho, Er, Tm, Yb, Lu) inorganic nanocages that has been discovered will be presented. A facile template-free synthetic route was developed for one step, high yield, and large scale synthesis of ternary NH4Ln 2F7 (Ln = Y, Ho, Er, Tm, Yb, Lu) nanocages. On the basis of our studies, these nanocages are thermodynamically stable forms of this group of NH4Ln2F7 compounds. The tendency of NH 4Ln2F7 (Ln = Y, Ho, Er, Tm, Yb, Lu) to form these new-type nanostructures is believed to have a close relationship with their inherent layered structures, similar to that of inorganic fullerene-like nanoparticles. This new type of nanocage can be easily doped with other lanthanide ions, which may endow these nanocages with novel properties. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Liang, Xin,Wang, Xun,Wang, Leyu,Yan, Ruoxue,Peng, Qing,Li, Yadong
-
p. 2186 - 2191
(2007/10/03)
-
- Fullerene-like rare-earth nanoparticles
-
A low-temperature hydrothermal synthesis has been employed to prepare the title materials in the form of their fluorides and hydroxides. Electron microscopy reveals their hollow and closed-cage structures (see HRTEM image). Such nanostructures can be expected to bring forth new opportunities in important research and application fields, such as biological labeling, luminescence, and catalysis.
- Wang, Xun,Li, Yadong
-
p. 3497 - 3500
(2007/10/03)
-
- Judd-Ofelt intensity parameters of trivalent lanthanide ions in a NaPO3-BaF2 based fluorophosphate glass
-
The spectroscopic properties of the trivalent lanthanide ions Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+ and Tm3+ in the fluorophosphate glass 75NaPO3-24BaF2-1LnF3 (where Ln = lanthanide ion) are described. The dipole strengths of the transitions in the absorption spectrum are parameterized in terms of three Ωλ (λ = 2, 4 and 6) Judd-Ofelt intensity parameters.
- Van Deun,Binnemans,Gorller-Walrand,Adam
-
-
- Thermodynamics of the rhombohedral-cubic phase transition of ROF with R=Y, La, Pr, Nd, Sm-Er
-
The temperatures and enthalpies of the rhombohedral-cubic phase transition of stoichiometric ROF with R=Y, La, Pr, Nd, Sm-Er, have been determined by differential scanning calorimetry. The temperatures of transition are found in the range 742-880 K in sat
- Petzel,Marx,Hormann
-
-
- Synthesis and thermal study of tris(ammonium) hexafluoro metallates(III) of some rare earths
-
Fluorination of oxides of rare earths using ammonium hydrogen fluoride at room temperature gave new compounds 3MF6*nH2O, where M = Y, La, Nd, and Pr.In the case of cerium, 4CeF8 is formed.The course of thermal decomposition of all these compounds is studied by thermogravimetry/differential thermal analysis (TG/DTA) and X-ray powder diffraction(XRD).Key words: hexafluoro metallates, rare earths, ammonium hydrogen fluoride, thermal decomposition, X-ray diffraction.
- Patwe, S. J.,Wani, B. N.,Rao, U. R. K.,Venkateswarlu, K. S.
-
p. 1815 - 1818
(2007/10/02)
-
- Syntheses, X-Ray Structures, and Properties of Complexes of Macrocyclic Hexaimines with Lanthanide Nitrates
-
Complexes 1> 1 = 2,7,13,18-tetramethyl-3,6,14,17,23,24-hexaazatricyclo8,12>tetracosa-1(23),2,6,8,10,12(24),13,17,19,21-decaene>, 1(H2O)>NO3.H2O (M = La, Ce, or Pr), and 1(H2O)2>2>NO33.4H2O (M = Nd, Sm, Eu, Gd, Tb, Dy, Ho, or Er) have been synthesized by a template condensation or by ligand exchange.The X-ray crystal structures of a member of each series, 1>, 1(H2O)>NO3.H2O, and 1(H2O)2>2>NO33.4H2O have been determined; the complexes contain the hexadentate macrocycle L1 co-ordinated to the lanthanide ion and are respectively 12-, 11-, and 10-co-ordinate.Properties including n.m.r. paramagnetic shifts are described.
- Arif, Ata M.,Backer-Dirks, J. D. Julius,Gray, Colin J.,Hart, F. Alan,Hursthouse, Michael B.
-
p. 1665 - 1674
(2007/10/02)
-
- Thermochemistry of rare-earth trifluorides, I. Fluorine bomb calorimetric determination of the enthalpies of formation of LaF3, PrF3, NdF3, GdF3, DyF3, HoF3, and ErF3
-
The energies of combustion of high-purity samples of lanthanum, praseodymium, neodymium, gadolinium, dysprosium, holmium, and erbium in fluorine to form the respective trifluorides were measured in a bomb calorimeter.The results obtained for the standard enthalpies of formation, ΔH0f(298.15 K)/kJ mol-1, are as follows: LaF3, -(1699.5 +/- 2.0); PrF3, -(1689.1 +/- 2.6); NdF3, -(1679.4 +/- 1.9); GdF3, -(1699.3 +/- 2.3); DyF3, -(1692.0 +/- 1.9); HoF3, -(1697.8 +/- 2.3); and ErF3, -(1693.6 +/- 1.9).
- Johnson, Gerald K.,Pennell, Rebecca G.,Kim, Kwang-Yil,Hubbard, Ward N.
-
p. 125 - 136
(2007/10/02)
-