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Showing papers on "Lanthanum published in 1972"


Journal ArticleDOI
TL;DR: In this article, a method for computing the matrix effects coefficient of H 2O, Na2O, MgO, Al2O3, SiO2, K2O.
Abstract: In X-ray fluorescence analyses, the matrix effects can be evaluated by computing appropriate coefficients. Utilising powder pellets of samples artificially prepared, a method for computing the matrix effects coefficient of H2O, Na2O, MgO, Al2O3, SiO2, K2O, CaO, TiO2, Fe2O3 for the analytical lines of thirteen elements: vanadium, chromium, nickel, copper, zinc, gallium, rubidium, strontium, zirconium, barium, lanthanum, cerium and lead is described. The computed coefficients have been used to analyse six international rock standards (the U.S. Geological Survey Standards: G-2, GSP-1, AGV-1, BCR-1, PCC-1, DTS-1).

373 citations


Journal ArticleDOI
28 Jul 1972-Science
TL;DR: Crushed single crystals of perovskite-like compounds RE1-XPb5MnO3 and RECoO3 compare favorably with commercial platinum catalysts in initial activity and lifetime, and are promising substitutes for platinum in devices for the catalytic treatment of auto exhaust.
Abstract: The perovskite-like compounds RE(1-X)Pb(5)MnO(3) and RECoO(3), where RE (rare earth) is lanthanum, praseodymium, or neodymium, are active catalysts for the oxidation of carbon monoxide. Crushed single crystals of these compounds compare favorably with commercial platinum catalysts in initial activity and lifetime. Therefore, these compounds are promising substitutes for platinum in devices for the catalytic treatment of auto exhaust.

254 citations


Journal ArticleDOI
TL;DR: The multiple signals in the 3D region of seven lanthanum(III) compounds are explained by the possibility of simultaneous transfer of an electron from the neighbour atoms to the empty 4f shell during the ionization.

115 citations


Journal ArticleDOI
TL;DR: In this article, multiorganometallic compounds were used to prepare high-purity submicron-size lead lanthanum zirconate-titanate (PLZT) powders which can be consolidated at low sintering temperatures to high-density piezoelectric and electrooptic ceramic bodies.
Abstract: Multiorganometallic compounds were used to prepare high-purity submicron-size lead lanthanum zirconate-titanate (PLZT) powders which can be consolidated at low sintering temperatures to high-density piezoelectric and electrooptic ceramic bodies. Simultaneous hydrolytic decomposition of lead isoamyloxide, lanthanum isopropoxide, and zirconium and titanium tertiary amyloxides produced quaternary titanate powders with particle sizes of 75 to 300 A and analyzed purity of 99.92%; the major contaminant was Na from an intermediate reaction product. Homogeneity and stoichiometry of the powders before and after processing were demonstrated by electron microscopy and chemical analysis. High-temperature X-ray diffraction indicated an amorphous material up to ∼600°C, where the crystalline phase was first observed. Powders prepared in this manner sintered to high-density fine-grained transparent bodies with uniform microstructure. The experimental results suggest that less rigorous consolidation methods are required with high-purity homogeneous precursor materials with fine particle size.

105 citations




Journal ArticleDOI
TL;DR: The tervalent rare earth cations lanthanum and gadolinium have been studied for their effect on canine cardiac sarcoplasmic reticulum and the reactive lanthanide ion concentration is not as predicted from solubility-product considerations.

46 citations


Journal ArticleDOI
TL;DR: Inhibition of calcium entry into the medullary cells by lanthanum may explain the inhibition of acetylcholine-induced or potassium-induced catecholamine release.

33 citations


Journal ArticleDOI
TL;DR: In this article, the binding energies of the M 4 (3 d 3/2 ) and M 5 (3d 5/2 ), as well as the N 2 (4 p 1/2 )) levels of lanthanum and cerium were found to be split into two components.
Abstract: X-ray photoelectron spectra have been measured on in situ evaporated films of yttrium, lanthanum, and cerium by the use of an electron energy analyser of the parallel plate electrode type. The binding energies of electronic core levels have been determined. Results are compared with the values cited in typical X-ray atomic energy tables. The binding energies of the M 4 (3 d 3/2 ) and M 5 (3 d 5/2 ) levels of lanthanum and cerium as well as the N 2 (4 p 1/2 ) and N 3 (4 p 3/2 ) levels of lanthanum are all found to be split into two components. Possible origins of the splitting are discussed, although no definite conclusion is drawn out.

26 citations


Journal ArticleDOI
C.E. Messer1, M.K. Park1
TL;DR: In this article, the hydrogen dissociation pressures have been measured as functions of composition and temperature for the face-centered cubic phases of praseodymium and samarium hydrides at 250 °-450 °C, hydrogen-to-metal ratios 2.2 to 2.7, and pressures 50-760 Torr.
Abstract: The hydrogen dissociation pressures have been measured as functions of composition and temperature for the face-centered cubic phases of praseodymium, neodymium and samarium hydrides at 250 °–450 °C, hydrogen-to-metal ratios 2.2 to 2.7, and pressures 50–760 Torr. The magnitudes of the pressures for the first two systems are close to those of the lanthanum and cerium hydride systems; the samarium hydride pressures are considerably higher. Enthalpies and entropies of solution H h − 1 2 H h 2 ° and S h - 1 2 S h 2 ° were evaluated from Van 't Hoff plots. Interaction energies between octahedral interstices and octahedral hydrogen atoms were evaluated from regular solution theory and compared with literature-based calculations for the corresponding lanthanum, cerium, neptunium, plutonium, and americium systems. All interaction energies were negative (attractive), of the order 1–3 kcal mole−1. In the lanthanum, cerium, and praseodymium hydride systems, the interaction energies decreased with increasing temperature; in the other systems the interaction energies increased with temperature to about 350 °C, then decreased. The resulting entropy effects are discussed. The transition from cubic to trigonal (hexagonal) samarium hydride was detected and investigated at high hydrogen-to-metal ratios, but the existence of considerable hysteresis precluded equilibrium measurements.

25 citations


Journal ArticleDOI
TL;DR: In this paper, a study of the growth and morphology of 6H-SiC whiskers obtained by the effect of lanthanum on silicon carbide crystals growing into a cavity in a SiC mass, heated in an inert ambient of 1 atm pressure, at temperatures between 2300 and 2600 °C.




Journal ArticleDOI
TL;DR: In this paper, the composition dependence of cubic → tetragonal phase transformation for solid solutions of UC 2 with LaC 2 and with CeC 2 is reported. And the appearance of UC from the cubic solid solutions on annealing shows that UC precipitation occurs above the β → α transition.

Journal ArticleDOI
TL;DR: In this paper, the room temperature, high pressure resistances of some La-Ce alloys have been studied in the presence of lanthanum, and it has been shown that the resistance anomaly associated with the γ→α phase change in pure cerium (f.c.→ f.c.) increases with increasing lanthanums content from a value of 7 kB for cerium to about 25 kB.
Abstract: The room temperature, high pressure resistances of some La-Ce alloys have been studied in the present work. The pressure of the resistance anomaly associated with the γ→α phase change in pure cerium (f.c.c.→ f.c.c.) increases smoothly with increasing lanthanum content from a value of 7 kB for cerium to about 25 kB for lanthanum. This suggests that the resistance anomaly in pure lanthanum could be associated with an electronic change similar to that observed in cerium, rather than due to the d.hex.→ f.c.c. structural change. The pressure at which the resistance anomaly associated with the α→α′ change in cerium occurs increases rapidly with increasing lanthanum content and the magnitude of the effect decreases such that it cannot be detected at above 40 % lanthanum, indicating a possible critical point for this transformation.

Patent
31 Aug 1972
TL;DR: A thermally stable, oxidation-resistant nickel-base alloy having good engineering properties for use in mechanical equipment operated at temperatures of up to 1600° F. or higher is provided by maintaining the nickel content above 50% by weight and including as essential elements from about 12 to about 18% chromium, from about 8 to 18% molybdenum and from about 0.005 to about 2.2% lanthanum by weight as mentioned in this paper.
Abstract: A thermally stable, oxidation-resistant nickel-base alloy having good engineering properties for use in mechanical equipment operated at temperatures of up to 1600° F. or higher is provided by maintaining the nickel content above 50% by weight and including as essential elements from about 12 to about 18% chromium, from about 8 to about 18% molybdenum and from about 0.005 to about 0.2% lanthanum by weight. Additional elements may be included in limited amounts provided that the average N v number of the alloy as defined herein is not substantially above about 2.5 and preferably is below about 2.4.

Patent
Kano T1, Nakano M1, Otomo Y1, Yamamoto H1
31 Jan 1972
TL;DR: OXYFLUORIDES of LANTHANUM, GADOLINIUM, YTTRIUM and LUTETIUM, ACTIVATED with ERBIUM, and CONTAINing YTTERBIUM as a SENSITIZER can be EFFICIENTly EXCITED to RED LUMINESCENCE by InFRARED RADIATION, and can be USED in CERTAIN LIGHT-PRODUCING APPLICATIONS as mentioned in this paper.
Abstract: OXYFLUORIDES OF LANTHANUM, GADOLINIUM, YTTRIUM AND LUTETIUM, ACTIVATED WITH ERBIUM, AND CONTAINING YTTERBIUM AS A SENSITIZER CAN BE EFFICIENTLY EXCITED TO RED LUMINESCENCE BY INFRARED RADIATION, AND CAN BE USED IN CERTAIN LIGHT-PRODUCING APPLICATIONS AND THE COMPOSITION OF THE OXYFLUORIDES CAN BE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: (LN1-Y-ZYBYERZ)OX/2F3-X WHEREIN LN IS AT LEAST ONE ELEMENT SELECTED FROM THE GROUP CONSISTING OF LANTHANUM, GADOLINIUM, YTTRIUM AND LUTETITUM, AND WHEREIN X, Y AND Z ARE 0.4$X$1.3, 0.06$Y $0.35 AND 0.008$Z$0.10, RESPECTIVELY.


Journal ArticleDOI
Shoji Suzuki1, I. Nagakura1, Takehiko Ishii1, T. Satoh1, Takashi Sagawa1 
TL;DR: In this paper, the authors compare the optical absorption spectra due to the 4d → 4f transition and the photoemission lines due to 4d electrons in lanthanum and cerium.

Journal ArticleDOI
TL;DR: In this article, the authors used pH-log UO2(NO3)2 slope of precipitation line to predict the average composition of hydrolytic species in equilibrium with the first solid phase formed in the system.

Patent
01 Jun 1972
TL;DR: In this article, the SILVER CATALYST COMPOSITIONS CONTAINING, as a PROMOTER, at least one METAL SELECTED from the group consisting of LANTHANUM, PRASEODYMIUN, NEODYMIUM, TERBIUM and DYSPROSIUM.
Abstract: THE SILVER CATALYST COMPOSITIONS CONTAINING, AS A PROMOTER, AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF LANTHANUM, PRASEODYMIUN, NEODYMIUM, TERBIUM AND DYSPROSIUM GIVE A HOGH SELECTIVITY IN THE OXIDATION REACTION ETHYLENE TO ETHYLENE OXIDE.


Patent
04 Oct 1972
TL;DR: In this paper, the authors discuss high brightness, high contrast, high conflict, and high resolution RARE EARTH CRYSTALLINE LUMINESCENT FILMS and processes for making SUCH FILMS.
Abstract: THIS INVENTION RELATES TO HIGH BRIGHTNESS, HIGH CONTRAST, HIGH RESOLUTION RARE EARTH CRYSTALLINE LUMINESCENT FILMS AND PROCESSES FOR MAKING SUCH FILMS. MORE PARTICULARLY, THE FILMS ARE RARE EARTH, CRYSTALLINE OXYSULFIDES OF LANTHANUM, GADOLINIUM, YTTRIUM AND LUTETIUM ACTIVATED WITH TRIVALENT RARE EARTH IONS HAVING ATOMIC NUMBERS FROM 59 THROUGH 70.

Journal ArticleDOI
01 Nov 1972-Talanta
TL;DR: A new reagent, Carboxynitrazo, gives a colour reaction with some rare earth elements and a possible procedure for the determination of lanthanum in the presence of ytterbium is discussed.

Patent
01 Nov 1972
TL;DR: In this paper, a process for the production of HIGHLY POLYMERIC POLYESTER is described, where the main purpose is to improve the efficiency of the production process.
Abstract: 1. IN A PROCESS FOR THE PRODUCTION OF HIGHLY POLYMERIC POLYESTER BY POLYCONDENSATION OF A POLYCONDENSABLE MATERIAL AT LEAST 85 MOLE PERCENT OF WHICH CONSISTS OF AT LEAST ONE BIS(DIHYDRIC ALCOHOL) ESTER OF AN AROMATIC DICARBOXYLIC ACID, OR AN OLIGOMER THEREOF, THE IMPROVEMENT COMPRISING THE EMPLOYMENT AS A CATALYST OF A CATALYTIC AMOUNT OF A COMPOSITION CONSISTING ESSENTIALLY OF A METALLIC COMPONENT AND AN ORGANIC COMPONENT, THE METALLIC COMPONENT BEING A METAL OXIDE OR A METAL SALT CONTAINING A WEAKLY ACIDIC ANION, SAID METAL IS SELECTED FROM THE GROUP CONSISTING OF ZINC, MANGANESE, ALUMINUM, LANTHANUM, COBALT, CALCIUM AND CADIUM, AND THE ORGANIC COMPONENT BEING A SIMPLE OR POLYMERIC COMPOUND OF THE STRUCTURE X3-O-Z(=O)(-X1)-X2 WHERE X1 IS -R OR -OR,X2 IS -R,X3 IS-H OR -R,Z IS AN ATOM OF A GROUP VB ELEMENT OF THE PERIODIC TABLE HAVING AN ATOMIC NUMBER GREATER THAN 7, AND EACH R, WHICH MAY BE THE SAME OF DIFFERENT, IS A MONOVALENT HYDROCARBON GROUP, WHEREIN THE MOLECULAR WEIGHT OF AT LEASTT ONE OF THE GROUPS R ATTACHED DIRECTLY TO THE ATOM Z IS GREATER THAN 145.

Journal ArticleDOI
TL;DR: In this paper, measurements of the equilibrium distribution of several lanthanide and actinide elements between liquid bismuth solutions and a variety of lithium halide salts were made in the temperature range 600-750°C.

Journal ArticleDOI
TL;DR: In this paper, the preparation of thin supported films of Ra, U, Np, Pu and Am isotopes has been studied using vacuum evaporation from electron-bombarded effusion cells.

Journal ArticleDOI
TL;DR: In this article, a procedure using a complexing agent (NTA) in paper electromigration has been devised to achieve rapid separation of fission product lanthanum, which permits direct observation of the decay of the 42 sec 144La without interference from the radiation of other fission products.
Abstract: A procedure using a complexing agent (NTA) in paper electromigration has been devised to achieve rapid separation of fission product lanthanum. This technique permits direct observation of the decay of the 42 sec 144La without interference from the radiation of other fission products. The γ-ray spectrum of 144La has been measured with a high-resolution Ge(Li) detector, and the following r-transitions were observed: 397, 434, 541, 586, 704, 734, 845, 951 and l,292keV. Their relative intensities were also determined. From the decay plots of the two strong photopeaks at 397 and 541 keV, the half-life of the 144La was determined as 42.4±0.6sec which is more accurate than that of 41±3sec previously reported. It is concluded that the separation procedure used in the present study can be adapted to the isolation of other short-lived fission products as well whenever their metal ions from the complexes by different values of the equilibrium constant.

Journal ArticleDOI
TL;DR: In this article, the complexes of lanthanum, praseodymium, neodynium, cerium and samarium with 1-substituted tetrazoline-5thiones have been prepared and their infrared spectra and magnetic susceptibilities measured.