Showing papers on "Lanthanum published in 1971"
TL;DR: Lanthanum cobalt oxide as potential auto exhaust catalyst from studies of activity in gas phase shows high potential for use as a catalyst for combustion.
Abstract: Lanthanum cobalt oxide as potential auto exhaust catalyst from studies of activity in gas phase
338 citations
Patent•
23 Dec 1971
TL;DR: In this paper, heat resistant and strengthened composite materials are obtained by mixing, and sintering in a non-oxidizing atmosphere, the combination of powders of aluminum nitride and/or silicon nitride, with powders or whiskers of silicon carbide, boron nitride or carbon.
Abstract: Heat resistant and strengthened composite materials are obtained by mixing, and sintering in a non-oxidizing atmosphere, the combination of powders of aluminum nitride and/or silicon nitride, with powders of an oxide of lanthanum, cerium, scandium, yttrium, and/or yttrium aluminum garnet, and with powders or whiskers of silicon carbide, boron nitride and/or carbon. The composite material so produced is characterized by high shock resistance and excellent mechanical strength.
75 citations
TL;DR: In the presence of fluoride complexing cations, the lanthanum fluoride electrode responds theoretically to free fluoride one to three decades below lO -6 M, the accepted limit in non-complexing solutions as discussed by the authors.
70 citations
TL;DR: The rare earth series consists of the elements 57, lanthanum, through 71, lutetium, and Yttrium, and is also found to occur with these elements in nature and to display similar chemical behavior as discussed by the authors.
Abstract: Publisher Summary The replacement of the tedious fractional crystallization method of separation by the ion-exchange techniques used commercially today has made most of the lanthanide elements available in large-scale quantities of high purity. The increased availability of these metals and their compounds in the past few years has in turn promoted research which has resulted in new commercial applications. The rare earth series consists of the elements 57, lanthanum, through 71, lutetium. Yttrium, element 39, is also found to occur with these elements in nature and to display similar chemical behavior and is therefore generally classified with them. All four compounds are pyrophoric, rather thermally stable, and give positive tests with Michler's ketone. Reactions with mercuric chloride, carbon dioxide, and benzophenone give, respectively, phenyl mercuric chloride, benzoic acid, and triphenylcarbinol in good yields. A polymeric formulation has been suggested to explain the involatility and insolubility of the dried products, the initially isolated solids being benzene soluble, possibly as the result of monomer stabilization by tetrahydrofuran coordination.
47 citations
TL;DR: A series of transition metal sulfides LaMS3, where M = Cr, Mn, Fe, and Co has been synthesized by high temperature sulfurization of the corresponding ternary oxides with CS2 as discussed by the authors.
31 citations
29 citations
Patent•
24 May 1971
TL;DR: Palladium-cerium and palladium-yttrium membranes are particularly suitable for use in the separation process of hydrogen from gaseous mixtures containing hydrogen as discussed by the authors.
Abstract: Membranes suitable for use in the separation of hydrogen from gaseous mixtures containing hydrogen, comprise an alloy of palladium and one or more elements selected from the group consisting of Yttrium and the Lanthanides but excluding Lanthanum and Praseodymium. Palladium-cerium and palladium-yttrium membranes are particularly suitable for use in the separation process.
28 citations
TL;DR: In this article, the metal-ligand ratios have been determined and it has been found that the extractions are uneffected by addition of sodium chloride and an inverse third-power relation is observed between D and the hydrogen ion concentration for varying HCl concentrations.
23 citations
TL;DR: In this paper, the ternary metal-alizarin complexan-fluoride systems were studied by recording absorption and continuous variations curves, and plotting theoretical curves of continuous variations for various ML-fluoricide complexes.
22 citations
Patent•
25 Jan 1971
TL;DR: A rare earth halide preferably a rare earth fluoride such as cerium tri-fluoride or lanthanum tri fluoride is used as a lubricant for die casting components as discussed by the authors.
Abstract: A rare earth halide preferably a rare earth fluoride such as cerium tri-fluoride or lanthanum tri-fluoride is used as a lubricant for die casting components.
22 citations
TL;DR: In this article, Thorium can be separated from uranium, yttrium, lanthanum and cerium by elution first with DMSO and then with 2 M nitric acid.
TL;DR: In this paper, the rate equation for the forward exchange reaction was shown to be: R=k T [H + ][ Eu 3+ ] [ La(EDTA) 1− ][ La 3+ ].
TL;DR: In this paper, the chemistry of diamagnetic nitrilotriacetate complexes of scandium, yttrium, lanthanum and lutecium in aqueous solution is studied.
Abstract: Proton nuclear magnetic resonance has been used to study the chemistry of the diamagnetic nitrilotriacetate complexes of scandium, yttrium, lanthanum and lutecium in aqueous solution Complexes with ligand-to-metal ratios of 1 and 2 are present depending of the solution conditions The ligand exchanges by spontaneous and by acid catalysed dissociation of the metal-bis-nitrilotriacetate, and also by a bimolecular process involving the free ligand and the complex The ligand exchange rate constants decrease with the ionic radii:lanthanum > yttrium > lutecium > scandium
Patent•
10 Nov 1971
TL;DR: In this article, an erbium metaphosphate mixture with ytterbium was used to produce laser emission at a wavelength of 1.536 microns, when disposed in a resonant cavity having an output reflector whose reflectance was a maximum of 80 percent.
Abstract: A laser device uses a material for incorporating into a glass laser host consisting essentially of a phosphate glass composed principally of an erbium metaphosphate admixed with an ytterbium metaphosphate. The properties of the glass may be varied by additional R(PO3)3 and S(PO3)2 contents wherein said R is a trivalent ion selected from the group consisting of aluminum, lanthanum, gadolinium, gallium, scandium, yttrium, neodymium, cerium, europium, manganese, molybdenum and chromium, and said S is a divalent ion selected from the group consisting of zinc, magnesium, cadmium, calcium, strontium or barium. The resulting glass composition provides a material capable of producing laser emission from the erbium ion at a wavelength of 1.536 microns, when disposed in a resonant cavity having an output reflector whose reflectance is a maximum of 80 percent.
TL;DR: In this paper, electron spin-resonance linewidth data, taken between 6 and 23 K, were compared with pulse-saturation-recovery times, measured between 2.5 and 3.5K, for three samples of Nd-doped lanthanum magnesium nitrate.
Abstract: Electron-spin-resonance linewidth data, taken between 6 and 23 K, are compared with pulse-saturation-recovery times, measured between 2.5 and 3.5K, for three samples of Nd-doped lanthanum magnesium nitrate. Both types of measurements indicate a dominant Orbach relaxation process. The relationship between the two types of data in the presence of a phonon-limited Orbach relaxation process is discussed. The fact that the linewidth data were uniform among the different samples, whereas the pulse-saturation-recovery data were concentration dependent, is interpreted as evidence that the Orbach relaxation process in this salt is phonon limited.
TL;DR: In this paper, small amounts of the metals Th, U, Np, PuI, and Am were dissolved individually into fcc La, and the superconducting transition temperatures T c of the alloys were measured and compared with that of La.
TL;DR: In this paper, the optical hydrogen vibrations in lanthanum dihydride and trihydride have been investigated by the energy gain scattering of cold neutrons, and the approximate frequency distributions, derived from the observed time-of-flight spectra, show peaks which correlate well with the known crystal structures.
Abstract: The optical hydrogen vibrations in lanthanum dihydride and lanthanum trihydride have been investigated by the energy‐gain scattering of cold neutrons The approximate frequency distributions, derived from the observed time‐of‐flight spectra, show peaks which correlate well with the known crystal structures In fcc lanthanum trihydride the optical bands are peaked at 940 and 515 cm−1 corresponding to hydrogen vibrating at tetrahedral and octahedral sites, respectively, and in lanthanum dihydride there is a single peak at 825 cm−1 due to tetrahedral hydrogen Other weak peaks have been observed and are thought to be due to vibrations of hydrogen atoms dissolved in the metal phase; this phase was identified by x rays in both samples A large width of the optical levels, a common feature in all metallic hydrides, was also observed for LaH2 and LaH3
TL;DR: In this paper, the equilibrium distribution of barium and several lanthanides between liquid bismuth solutions and molten lithium halide salts yielded distribution coefficients that could be used in conjunction with published thermochemical data to estimate activity coefficients for the various elements (at low concentration) in liquid Bismuth.
Abstract: Measurements of the equilibrium distribution of barium and several lanthanides between liquid bismuth solutions and molten lithium halide salts yielded distribution coefficients that could be used in conjunction with published thermochemical data to estimate activity coefficients for the various elements (at low concentration) in liquid bismuth. The standard state for each element was the pure metal. At 600° C, the temperature at which most data were available, values of log γM were about −12 for barium, −13 for lanthanum, −14 for cerium, −8 for neodymium, and −9 for gadolinium and dysprosium.
TL;DR: In this paper, the free energy, enthalpy, and entropy for the formation of tripositive lanthanum, praseodymium and ytterbium complexes with histidine (histH) were determined at 37·0 °C and I= 3·00 mol l−1 (with sodium perchlorate).
Abstract: The changes in free energy, enthalpy, and entropy for the formation of tripositive lanthanum, praseodymium, neodymium, samarium, gadolinium, dysprosium, erbium, and ytterbium complexes with histidine (histH) have been determined at 37·0 °C and I= 3·00 mol l–1(with sodium perchlorate). The formation constants, and thus the free-energy changes, were measured potentiometrically, and the enthalpy changes were measured by calorimetry. The entropy changes were calculated from the relationship ΔGn°=ΔHn°–TΔSn°. The experimental results for the lanthanides studied are interpreted in terms of the formation of three complexes: [Ln(hist)]2+, [Ln(hist)2]+, and [Ln(histH)]3+. By combining data at 25 °C and at 37 °C, heat capacity changes (ΔCp) for the complexing reactions have been calculated at the mean temperature of 31 °C. The trends reported in ΔCp data as one crosses the lanthanide series could be explained by changes in the hydration numbers of the lanthanide ions.
TL;DR: Trishexafluoro-2propoxides of yttrium, lanthanum, neodymium and erbium have been prepared by the ammonia method, directly from the hydrated rare earth chlorides, dehydrated in situ by trimethyl orthoformate as discussed by the authors.
Abstract: Tris-hexafluoro-2-propoxides of yttrium, lanthanum, neodymium and erbium have been prepared, by the ammonia method, directly from the hydrated rare earth chlorides, dehydrated in situ by trimethyl orthoformate. The compounds are not volatile.
TL;DR: In this article, the evaporation coefficient of chromic oxide and lanthanum chromite (LaCrO3) was studied by means of both the target-collection method combined with the Knudsen-cell and the langmuir free eva-oration method at temperatures ranging from 1650° to 1900°C in vacuum.
Abstract: Evaporations of chromic oxide and lanthanum oxide component from the sintered body of lanthanum chromite (LaCrO3) were studied by means of both the target-collection method combined with the Knudsen-cell and the langmuir free evaporation method at temperatures ranging from 1650° to 1900°C in vacuum.The results obtained were as follows:(1) The vapor pressure of chromic oxide componet over the lanthanum chromite measured by the target-collection method was about one-fifth of that of pure chromic oxide, and the ratios of vapor pressures of lanthanum oxide component (PLa2O3) to chromic oxide component (PCr2O3) were 0.045-0.050.(2) PCr2O3 over LaCrO3 measured by the Langmuir method was about 1/100 of that measured by the target-collection method mentioned above, and then the evaporation coefficient of Cr2O3 was determined as 0.01.(3) The X-ray diffraction patterns of the surfaces of LaCrO3 after the evaporations did not show those of mixtures of the usual lanthanum oxide and the chromic oxide and the chromic oxide. It was thus confirmed that the lanthanum oxide contaning 2-3 mol% Cr2O3 formed on the surface turned into the C-type rare earth oxide (cubic) at 1900°C in vacuum and that the decomposition reaction proceeding at a boundary between the surface layer of La2O3 and the original part of LaCrO3 was a rate-determining step for the evaporation rate.
TL;DR: In this article, a weak peak was detected at the L III X-ray emission edge of lanthanum metal and assigned to transitions involving conduction band electrons, L III O IV.V and L III P I.
Patent•
20 Oct 1971
TL;DR: In this article, a process for preparing alkoxides of the lanthanide elements, such as lanthanum, cerium, praseodymium and neodynium, in high yields and at increased reaction rates, is provided by reacting a lanthanides element with isopropyl alcohol in the presence of a catalytic amount of mercuric iodide or a mixture of mercureic chloride and mercurric acetate.
Abstract: A process for preparing alkoxides of the lanthanide elements, such as lanthanum, cerium, praseodymium and neodymium, in high yields and at increased reaction rates, is provided by reacting a lanthanide element with isopropyl alcohol in the presence of a catalytic amount of mercuric iodide or a mixture of mercuric chloride and mercuric acetate.
TL;DR: The formation constants of 3-acetyl-4- hydroxycoumarin (ahc) and dehydroacetic acid (dha) complexes were determined pH-metrically at 35° in 50% v/v aqueous dioxan medium with 0.100M sodium perchlorate as the constant ionic concentration as discussed by the authors.
Abstract: The formation constants (K1, K2, and β2) of the complexes of 3-acetyl-4- hydroxycoumarin (ahc) and dehydroacetic acid (dha) and their respective oximes, ahco and dhao, with iron(II), cobalt(II), nickel(II), copper(II), zinc(II), calcium(II), magnesium(II), cadmium(II), dioxouranium(VI), iron(III), aluminium(III), scandium(III), indium(III), yttrium(III), and lanthanon(III) ions (lanthanum to lutetium inclusive with the exception of promethium) have been determined pH-metrically at 35° in 50% v/v aqueous dioxan medium with 0.100M sodium perchlorate as the constant ionic concentration, using Calvin and Wilson's pH-metric technique. The trends in the formation constants of these complexes are discussed. It is observed that, except in the case of Co2+, Ni2+, and Cu2+ ions, for which chelation through nitrogen donors is more favoured, all other ions prefer coordination through oxygen donors.
TL;DR: In this paper, a method was described for the determination of 0.001-0.008 % of lanthanum in steels by flame emission spectrophotometry, where the organic phase was sprayed into an air-acetylene flame and the emission intensity measured at 743 nm.