Showing papers on "Lanthanum published in 1973"

Structure and properties of reduced LaCoO3

Abstract: Changes occurring in the chemical state, and the crystallographic and electronic structure of LaCoO3 in a reducing atmosphere were determined. These determinations involved the use of thermogravimetric and calorimetric techniques, x‐ray diffraction, and magnetic property measurements. It was shown that the reduction process proceeded through the formation of a series of oxygen‐deficient structures. In the 0–3.25 wt% weight‐loss region, corresponding to the general formula LaCo1−xO3−y, where 0.0

The action of lanthanum and manganese on anaphylactic histamine secretion.

Abstract: 1. In the concentration range 1 nM to 1 muM, lanthanum inhibited the calcium-dependent component of anaphylactic histamine release, but was without effect on the component which was independent of calcium.2. The inhibition of anaphylactic histamine release by lanthanum can be reversed by increasing the calcium ion concentration. The pA(2) for the lanthanum-receptor interaction was found to be 7.6.3. Lanthanum also inhibited the activation of anaphylactic histamine release by strontium ions.4. The inhibition of anaphylactic histamine release by lanthanum was reversed by eluting the lanthanum from the cells.5. In the concentration range 1 to 300 nM, lanthanum had no effect on the histamine release induced by compound 48/80 in a calcium-free medium, but the effect of calcium on the istamine release by compound 48/80 was antagonized by lanthanum in this range of concentrations.6. At concentrations of 10 muM and greater, lanthanum induced a release of histamine in the absence of antigen.7. In the concentration range 0.5 to 4.0 mM, manganese inhibited the calcium-dependent component of anaphylactic histamine release, but was without effect on the component which is independent of calcium. The inhibition of anaphylactic histamine release by manganese could be reversed by increasing the calcium ion concentration.

Nickle base high temperature abradable material

Abstract: A homogeneous and porous abradable seal material structure comprising principally gamma , gamma '' and/or Beta phases for use in elevated temperature operating apparatus consisting essentially of, by weight, 60-80% Ni, 2-12% Cr, 1-10% Co, 4-20% Al, up to 3% of a refractory metal selected from the group consisting of yttrium, hafnium and lanthanum and 3-15% inert powder material selected from the group consisting of diatomaceous earth (D.E.), boron nitride, silicon glass, mica, vermiculite asbestos, molybdenum disulfide, graphite, cobalt oxide, cerium oxide and zinc oxide.

Method for eliminating nitrogen oxides and catalyst composition for use in practicing said method

Abstract: Toxic substances contained in exhaust gases, especially nitrogen oxides contained in exhaust gases from automobiles, can be effectively eliminated, even in the presence of oxygen, by contacting such exhaust gases with a catalyst composition comprising iron or iron oxide, silver or silver oxide, at least a member selected from the group consisting of copper, beryllium, zinc, lead, indium, lanthanum, cerium and oxides of these metals, and a carrier. Especially good results can be obtained by employing a catalyst composition obtained by treating a composition comprising iron or iron oxide, silver or silver oxide, copper or copper oxide and a carrier with hydrogen sulfide, or by employing a catalyst composition comprising sulfides of iron, silver and copper supported on a carrier.

The preparation and purification of americium metal by evaporation

Abstract: In order to redetermine some physical and chemical properties of americium metal, several grams of 241 Am have been prepared by two independent methods: lanthanum reduction of the oxide and thermal dissociation of the intermetallic compound Pt 5 Am. After its separation from excess lanthanum or alloy constituent by evaporation, americium metal was further purified by sublimation at 1100 C and 10 −6 Torr. Irrespective of the method of preparation, the temperatures of evaporation or condensation and the material of the condenser, the americium samples displayed the same d.h.c.p. crystal structure. As determined by vacuum hot extraction, the oxygen, nitrogen and hydrogen contents are equal or smaller than 250, 50 and 20 ppm, respectively.

Magnetic properties of high purity yttrium, lanthanum, and lutetium and the effects of impurities on these properties

Abstract: Magnetic susceptibility measurements have been carried out on single and polycrystalline specimens of lutetium between 1.5 and 300 °K by the Faraday method. Its susceptibility was found to be paramagnetic and almost independent of temperature. A broad maximum centered at approximately 120 °K was found. Due to the discrepancies in past results of yttrium and lanthanum, their susceptibilities were also measured. Yttrium and lutetium were found to have χa greater than χc. Provided the specimens were of high purity, the relationship χpoly = (2/3)χa + (1/3)χ was well obeyed. Oxygen and hydrogen were found in general to lower the susceptibilities of these metals. The presence of an fcc phase in lanthanum was found to increase its susceptibility relative to a dhcp phase. An estimate of the susceptibility of pure fcc lanthanum is given.

High-temperature oxidation of lanthanum hexaboride

Abstract: 1. A study, based on kinetic investigation and metallographic examination, was made of the high-temperature oxidation of lanthanum hexaboride in air in the temperature range 500–1200°C. 2. On the basis of thermodynamic calculations of the equilibria in the systems LaB6-oxygen (nitrogen) at temperatures of 298–2000°K, it was established that, from the thermodynamic point of view, LaB6 is unstable in oxygen and nitrogen atmospheres. It was also found that, in the process of oxidation of LaB6, the most probable are the reactions resulting in the formation of La2O3 and B2O3. The reactions yielding lanthanum and AI3 and also La2O3 and free boron are also thermodynamically probable. 3. On the internal scale/LaB6 interface, the existence was detected of the lower lanthanum boride LaB4, which constitutes an intermediate oxidation product of the starting hexaboride. 4. It is shown that, during the oxidation of LaB6, an unknown phase — possibly LaB6 of increased boron content — is formed.

Method for preparing lead lanthanum zirconate-titanate powders

Abstract: High purity, submicron-size lead lanthanum zirconate-titanate powders are prepared by the simultaneous hydrolytic decomposition of lead isoamyloxide, lanthanum isopropoxide, and zirconium and titanium tertiary amyloxides The powders are a source of raw material for consolidation into theoretically dense ferroelectric, antiferroelectric and/or electrooptic bodies with superior electrical and optical properties

Method for reducing nitrogen oxides

Abstract: Catalysts for conversion of nitrogen oxides comprises a porous ceramic carrier, and 01 to 10% by weight of copper oxide in terms of copper metal, 01 to 20% by weight of lanthanum oxide in terms of lanthanum metal and 001 to 12% by weight of zirconium oxide in terms of zirconium metal, based on the weight of the carrier, these oxides being supported on the carrier The catalysts are brought in contact with a gas containing nitrogen oxides in the presence of ammonia and sulfur oxides, thereby decomposing and converting the nitrogen oxides

Synthesis of aromatic amines by reaction of aromatic compounds with ammonia

Abstract: An improved process is provided for producing an aromatic amine from ammonia and an aromatic compound which comprises reacting the aromatic compound with ammonia at a temperature of from about 150° C. to about 500° C. and at a pressure of from about 10 to about 1000 atmospheres in the presence of a conditioned nickel/nickel oxide/zirconium oxide cataloreactant containing an oxide of lanthanum, samarium, holmium, europium, erbium, yttrium, praseodymium, neodymium, terbium, ytterbium, dysprosium or a mixture of any of them.

Heterogeneous catalyst for oxidation of propylene into propylene oxide in the liquid phase and method for preparing it

Abstract: A heterogeneous catalyst for oxidation of propylene into propylene oxide in the liquid phase which is a carrier with active components supported thereon, the latter being oxides of scandium, yttrium, indium, gallium, thallium, or rare-earth elements of the lanthanum group, or mixtures of oxides of the above metals. In addition to with said active components, the catalyst can also contain silver, oxides of vanadium, molybdenum, tungsten, bismuth, manganese, or tantalum, or mixtures of the above active components. The method for preparing the catalyst consists in that the carrier is treated with an aqueous solution of a mineral acid or a mixture of mineral acids at 80° to 100°C, washed with water and dried at 300° to 400°C. The thus treated carrier is impregnated with aqueous solutions of salts of the corresponding metals. The impregnated carrier is treated at a temperature of 700° to 800°C. The heterogeneous catalyst ensures high selectivity (to 90 per cent) of the process of oxidation of propylene into propylene oxide in the liquid phase, the conversion of propylene being as high as 30 per cent, and also accelerates markedly the process, ensuring a reaction rate 1.5-2 times higher than the reaction rates obtainable with the known catalyst. Furthermore, said catalyst possesses high mechanical strength.

Diffusion of 140La in B.C.C. γ-lanthanum and δ-cerium

Abstract: The serial-sectioning method has been used to determine the self-diffusion coefficients in b.c.c. γ-lanthanum and the solute diffusivities of lanthanum in b.c.c. S-cerium. The results are expressed by D La La = 1.3 × 10–2 exp (-24500/RT) cm2/sec and D Ce La = 3.8 × 10–2 exp (-24500/RT) cm2/sec. The similarity of the diffusion characteristics in the different rare-earth metals casts doubt on the validity of the activated interstitial model put forward in order to account for the peculiar diffusion behaviour in the b.c.c. phases of cerium and plutonium.

The thermoelectric power of cerium, lanthanum, nickel and cobalt in the vicinity of the melting point

Abstract: The thermoelectric powers of cerium, lanthanum, nickel and cobalt have been measured at temperatures just above and just below the melting point. The results, which seem to conform to a general pattern of behaviour, are compared with the other electronic transport parameters.

Sorption of lanthanum(III), cobalt(II) and iodide ions at trace concentrations on ferric hydroxide

Abstract: The sorption of lanthanum(III), cobalt(II) and iodide traces was studied in dependence on the solid-liquid contact time, pH value and the properties of the carrier (internally or externally formed). The ferric hydroxide carrier was prepared by mixing aqueous ferric chloride and ammonia solutions. The results are discussed in regard to colloidal properties of the ferric hydroxide and mechanisms of sorption.

Catalyst of cobalt oxide and a rare earth metal oxide and its method of preparation

Abstract: Catalysts in the form of shaped bodies having adequate mechanical strength for use in industrial processes and containing active cobalt (II, III) oxide together with an oxide of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium, or a mixture of at least two of these oxides. The catalysts are prepared by coprecipitating from solution as carbonates or basic carbonates, cobalt and at least one of the elements of the oxides, washing and drying the precipitate and heating the dried precipitate within the temperature range of from 250* to 450*C for a period of time sufficient to convert the carbonates substantially to their respective oxides, comminuting the mixture of oxides, shaping the mixture into bodies and heating the shaped bodies within the temperature range of from 600* to 850*C.

Antioxidants for polyarylether ketones

Abstract: Incorporation into polyarylether ketones of a metal oxide selected from the group of amphoteric metal oxides consisting of the oxides of aluminum, beryllium, bismuth, cadmium, cerium, gallium, germanium, lanthanum, lead, manganese, tin, titanium, zinc, zirconium, uranium and mixtures thereof significantly enhances the oxidation resistance of said polyarylether ketones.

Silver electrical contact materials containing La{hd 1{118 x{b Sr{hd x{b CrO{HD 3

Abstract: The material consists of a mixture of silver and 1.0 to 20 weight per cent of lanthanum, strontium chromite of the formula La1-xSrxCrO3, where the values of x lie between 0 and 1.0. The addition of 2.5 to 20 weight per cent of cadmium oxide further improves the electrical contact material by providing anti-weld properties to the contact interface. The electrical contacts are formed from the contact material by powder metallurgy techniques.

Growth and some properties of lanthanum sulphate enneahydrate single crystals

Abstract: A technique for the growth of single crystals of Lanthanum Sulphate Enneahydrate from saturated aqueous solution by slow program-heating under different growing conditions has been developed. Polarized Raman spectrum and vibrational assignments of an oriented single crystal are reported. Es wurde eine Technik entwickelt fur die Zuchtung von Einkristallen von Lanthansulfat-enneahydrat aus einer ubersattigten wasrigen Losung durch langsame und programmierte Warmebehandlung unter verschiedenen Wachstumsbedingungen. Berichtet wird uber polarisierte Raman Spectra und Vibrationsanordnungen eines orientierten Einkristalls.

Catalytic oxidation of α-olefins

Abstract: In the oxidation of α-olefins in the gas phase to α,β-olefinically unsaturated aldehydes and carboxylic acids with molecular oxygen in the presence of an inert gas using a catalyst containing molybdenum and bismuth with elements as oxides or mixed oxides at from 280° to 450° C a content of indium and/or aluminum and/or lanthanum and/or gallium as oxide or mixed oxide results in an improvement in the conversion and/or activity and/or life of the catalyst.

Micro and semimicro determination of arsenate using ion-selective electrodes

Abstract: An indirect method for the microestimation of 0.75 to 15 ppm (1−10−5 to 2·10−4M) of As(V) has been described: Arsenate is precipitated with lanthanum nitrate at a pH of 8.65. The excess of lanthanum is titrated with standard fluoride, using a fluoride ion-selective electrode. Equivalence points are located on volume-corrected Gran's plot paper. This method can also be used to estimate the sum of arsenate and phosphate. For larger amounts of arsenate and for increased precision and accuracy, potentiometric titration with lead perchlorate, using a lead ion-selective electrode, is recommended. Other possibilities for determining arsenate and a method for estimating tungstate are suggested.

Study of LaFe12O19 from Mössbauer spectra

Abstract: A study of lanthanum ferrite, LaFe12O19, by use of the Mossbauer effect has contributed experimental data on the temperature dependence of the internal magnetic field on the sites of the57Fe nuclei, on isomer shift and on quadrupole splitting in the region from 90 to 820K. The Curie temperature was determined at 697K. The Mossbauer spectra of lanthanum and thallium lanthanum ferrite suggest that a special Fe2+ sublattice is not present.