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Showing papers on "Lanthanum published in 1969"


Journal ArticleDOI
TL;DR: The relative heat of formation and the reduced melting temperatures of the lanthanide compounds are correlated with the magnitude of the contraction in these compounds relative to the contraction of the pure metals.
Abstract: The relative heats of formation and the reduced melting temperatures (the melting point of the compound divided by the melting point of the metal) of the lanthanide compounds are correlated with the magnitude of the lanthanide contraction in these compounds relative to the lanthanide contraction in the pure metals If the lanthanide contraction (as determined from the lattice constants) in the compounds is greater than that observed for the metals, the heat of formation is expected to increase as one proceeds from lanthanum to lutetium The opposite is expected if the lanthanide contraction is less in the compounds than in the metals This has been substantiated for the five series for which sufficient thermodynamic data exist, specifically, RCd, RCl 3 , RH 2 , RMg and R 2 O 3 For the melting points, 15 of 17 lanthanide compound series show agreement between the observed reduced melting points and that expected from the relative lanthanide contraction Discrepancies are more likely to occur when correlating the melting points, since only part of the various bonds, RM, MM and RR, are broken upon melting, than for the heats of formation since this quantity is a measure of forming all of the bonds in the crystal

108 citations


Journal ArticleDOI
TL;DR: In this article, the electrical properties of both pure and strontium-doped lanthanum chromite are described, and for doped material a mobility deduced of 5×10−7 m2 v−1 s−1 at 300°k and 3× 10−6 m 2 v− 1 s− 1 at 1400°k.
Abstract: The properties of strontium-doped lanthanum chromite (La084Sr016CrO3) are discussed, with particular attention to its application as an electrode material for MHD power generation. The influence of firing temperature on the ceramic properties and the behaviour of strontium carbonate as a sintering agent are described. The thermal conductivity is 51 w m−1 degk−1 between 1100 and 2000°k, and the thermal expansion 90×10−6 degk−1 averaged between 300 and 1100°k. Thermal shock resistance is fair and chemical stability is very good. The incorporation of strontium is found to reduce markedly the volatility in oxidizing atmospheres compared with that for pure lanthanum chromite. The electrical properties of both pure and strontium-doped lanthanum chromite are described, and for doped material a mobility deduced of 5×10−7 m2 v−1 s−1 at 300°k and 3×10−6 m2 v−1 s−1 at 1400°k. The electrical results are tentatively discussed using the formalism of Goodenough.

57 citations


Journal ArticleDOI
TL;DR: In this paper, a method was proposed for the determination of silicon, aluminium, titanium, iron, calcium, magnesium, sodium and potassium in various silicates by atomic absorption spectrophotometry.

50 citations


Journal ArticleDOI
TL;DR: In this paper, the acidity of the X and Y zeolites exchanged by hydrogen, calcium, and lanthanum ions was investigated and the characteristic features of acid sites were found as compared with those of an amorphous silica-alumina cracking catalyst.
Abstract: The acidic characters of the X and Y zeolites exchanged by hydrogen, calcium, and lanthanum ions were investigated. Very characteristic features of the acid sites were found as compared with those of an amorphous silica-alumina cracking catalyst. The acidity is generally larger in the zeolites (2–3 meq/g) than in a silica-alumina (0.5 meq/g). The acid strength is more widely distributed in the zeolites (H0=+3.3−<−8.2) than in a silica-alumina (H0<−8.2). Very important is the fact that the acid site increases not only in number but also in strength with an increase in the degree of ion exchange. The results on cumene cracking are in line with these results.

39 citations



Journal ArticleDOI
TL;DR: In this article, the titration curves have been analysed by rigorous equilibrium calculations with the computer program HALTAFALL, and they have been shown to enter the solid phase, forming precipitates with the formula LaF3-xAcx (0

33 citations




Journal ArticleDOI
TL;DR: In this article, the equilibrium extraction mechanism of lanthanum nitrate from aqueous solutions by purified water equilibrated di-(2-ethylhexyl) phosphoric acid was studied at 25°C through material balance analysis of equilibrium phases.

21 citations


Patent
Louis J Favreau1
30 Apr 1969
TL;DR: A hairpin rhenium filament coated with lanthanum boride and with a fine tungsten tip attached to the filament serves as an efficient source of electrons as discussed by the authors.
Abstract: A field emission cathode comprises a hairpin rhenium filament coated with lanthanum boride and with a fine tungsten tip attached to the rhenium filament serves as an efficient source of electrons. The presence of free lanthanum atoms at the tungsten surface lowers the work function and enhances the field emission from the tungsten tip.

21 citations


Patent
Lewis Charles Hoffman1
24 Oct 1969
TL;DR: In this paper, the authors present an OXIDE of the formulae (MZBI2-X)(M''YRU2- )O7-Z 7-Z, where each node is at least one metal selected from the group consisting of PLATINUM, TITANIUM, TIN, CHROMIUM, RHODIUM, IRIDIUM, IMAXIUM, ROI, RHENIUM, ZIRCONIUM, ANTIMONY and GERMANIUM.
Abstract: RESISTOR COMPOSITIONS, WHICH YIELD, UPON FIRING, SMOOTH RESISTORS HAVING A WIDE RANGE OF RESISTANCE, LOW TCR''S AND GOOE STABILITY PROPERTIES, COMPRISING (1) AN OXIDE OF THE FORMULA (MZBI2-X)(M''YRU2- )O7-Z WHEREIN M IS AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF YTTRIUM, LANTHANUM, THALIUM, INDIUM, CADMIUM, LEAD AND THE RARE EARTRH METALS OF ATOMIC NUMBER 58-71 INCLUSIVE, M'' IS AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF PLATINUM, TITANIUM, TIN, CHROMIUM, RHODIUM, IRIDIUM, RHENIUM, ZIRCONIUM, ANTIMONY AND GERMANIUM, (2) AN INORGANIC BINDER, (3) NOBLE METAL, AND (4) OPTIONALLY, A BINARY OXIDE (E.G., CO3O4). THE CONTROL OVER PROPERTIES AFFORDED BY THIS COMBINATION OF INGREDIENTS AND PROPORTION THEREOR ENHANCES THE SIGNIFICANCE OF THIS INVENTION.

Journal ArticleDOI
TL;DR: In this article, the authors derived evidence for near octahedral coordination of Yb3+ in lanthanum metaphosphate, zinc-alumino phosphate, alkali-alkaline earth silicate, and alkaline earth germanate glasses using optical absorption and emission spectra near 20°K.

Patent
27 Jun 1969
TL;DR: A HYDROCARBON CONVERSION CATALYST COMPRISING LANTHANUM, CHROMIUM, IRON, and OXYGEN in a LANTHANEUM CROMIUM FERRITE PEROVSKITE-type STRUCTURE as discussed by the authors.
Abstract: A HYDROCARBON CONVERSION CATALYST COMPRISING LANTHANUM, CHROMIUM, IRON AND OXYGEN IN A LANTHANUM CROMIUM FERRITE PEROVSKITE-TYPE STRUCTURE.

Journal ArticleDOI
TL;DR: The electromotive force of cells of the type La(s)/LiCl/KCl (eutectic) + LaCl3/(La +Zn, saturated liquid alloy) has been measured over the temperature range 450-600 °C.
Abstract: The electromotive force of cells of the type La(s)/LiCl–KCl (eutectic) + LaCl3/(La + Zn, saturated liquid alloy) has been measured over the temperature range 450–600 °C. Thermodynamic functions for...

Journal ArticleDOI
TL;DR: In this article, the distribution behavior of lanthanum and actinium at tracer concentrations was studied in metal chelate extraction systems where the organic phase was chloroform containing dibutylphosphate, thenoyltrifluoroacetone (TTA), β-isopropyltropolone or 5,7-dichloroxine.
Abstract: Distribution behavior of lanthanum(III) and actinium(III) at tracer concentrations was studied in metal chelate extraction systems where the organic phase was chloroform containing dibutylphosphate, thenoyltrifluoroacetone (TTA), β-isopropyltropolone or 5,7-dichloroxine. The separation factors for this pair of ions by extraction with these four chelating ligands were determined. The distribution behavior was also studied in the adduct chelate extraction systems where the organic phase was carbon tetrachloride containing mixed ligands, TTA-tributylphosphate (TBP) or TTA-methyl isobutyl ketone (MIBK). The adduct formation constants for actinium-(III)-tris-TTA chelate with these neutral ligands were determined. Results were compared with previous results on the distribution behavior of other trivalent actinide and lanthanide ions in these systems. It was concluded that the separation of lanthanum-actinium was somewhat different from the separation of europium-americium in the same chelate extraction systems....

Patent
30 Apr 1969
TL;DR: In this paper, a method for fabricating cathodes with a lanthanum boride coating is disclosed in which the coating is applied to any base metal by spraying with a plasma flame spray.
Abstract: A method for fabricating cathodes with a lanthanum boride coating is disclosed in which the coating is applied to any base metal by spraying with a plasma flame spray. One plasma source is a spray gun utilizing an electric arc discharge through which a plasma gas is passed so that a plasma of ionized gas issues from the spray gun into which is injected a carrier gas having lanthanum boride powder suspended therein. The high-temperature plasma flame appearing at the nozzle of the spray gun melts the lanthanum boride (LaB6) almost instantly and the droplets formed thereby are carried to the surface of a prepared base material.

Patent
Kenneth E Schubert1
28 Nov 1969
TL;DR: In this article, the authors present an OXIDE of the formulae (MXBI2-X)M''YRU2-Y)O7-Z where each metal is at least one METAL selected from the group consisting of PLATINUM, TITANIUM, TIN, CHROMIUM, RHODIUM, IRIDIUM, IMAX, RHENIUM, ZIRCONIUM, ANTIMONY and GERMANIUM.
Abstract: RESISTOR COMPOSITIONS, WHICH YIELD, UPON FIRING, SMOOTH RESISTORS HAVING A WIDE RANGE OF RESISTANCES, LOW TCR''S AND GOOD STABILITY PROPERTIES, COMPRISING (1) AN OXIDE OF THE FORMULA (MXBI2-X)M''YRU2-Y)O7-Z WHEREIN M IS AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF YTTRIUM, LANTHANUM, THALLIUM, INDIUM, CADMIUM, LEAD AND THE RARE EARTH METALS OF ATOMIC NUMBER 58-71 INCLUSIVE, M'' IS AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF PLATINUM, TITANIUM, TIN, CHROMIUM, RHODIUM, IRIDIUM, RHENIUM, ZIRCONIUM, ANTIMONY AND GERMANIUM (2) AN INORGANIC BINDER, AND (3) A REQUIRED AMOUNT OF CADMIUM OXIDE OR OF A CADMIUM OXID PRECURSOR. THE CONTROL OVER PROPERTIES AFFORDED BY THIS COMBINATION OF INGREDIENTS AND PROPORTIONS THEREOF ENHANCES THE SIGNIFICANCE OF THIS INVENTION.

Patent
Michael John Popowich1
24 Oct 1969
TL;DR: In this paper, the authors present an OXIDE of the formulae (MXBI2-X(M''YRU2-Y)O7-Z) where each member of a group has at least one metal selected from the group.
Abstract: RESISTOR COMPOSITIONS, WHICH YIELD, UPON FIRING, SMOOTH RESISTORS HAVING A WIDE RANGE OF RESISTANCES, LOW TCR''S AND GOOD STABILITY PROPERTIES, COMPRISING (1) AN OXIDE OF THE FORMULA (MXBI2-X(M''YRU2-Y)O7-Z WHEREIN M IS AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF YTTRIUM, LANTHANUM, THALLIUM, INDIUM, CADMIUM, M'' IS AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF PLATINUM, TITANIUM, TIN, CHROMINUM, RHODIUM, IRIDIUM, RHENIUM, ZIRCONIUM, ANTIMONY AND GERMANIUM, (2) AN INORGANIC BINDER, AND (3) A REQUIRED AMOUNT OF PLATINUM. THE CONTROL OVER PROPERTIES AFFORDED BY THIS COMBINATION OF INGREDIENTS AND PROPORTIONS THEREOF ENHANCES THE SIGNIFICANCE OF THIS INVENTION.

Patent
R Ropp1
13 May 1969
TL;DR: In this article, the ORTHONIOBATE (orthoniobate) is the preferred competition and is provided by UTILIZING a 1:1 GRAM ATOM RATIO of YTTRIUM, LANTHANUM, GADOLINIUM, and GADOIUM to NIOBIUM.
Abstract: LUMINESCENT COMPOSITIONS OF THE SYSTEM COMPRISING YTTRIUM, LANTHANUM, GADOLINIUM, OR COMBINATIONS THEREOF, NIOBATE ACTIVATED BY SELECTED RARE EARTH METALS ARE SPECIFIED. THE ORTHONIOBATE IS THE PREFERRED COMPOSITION AND IS PROVIDED BY UTILIZING A 1:1 GRAM ATOM RATIO OF YTTRIUM, LANTHANUM, AND GADOLINIUM TO NIOBIUM. LUMINESCENT COMPOSITIONS OF THE SYSTEM ARE ALL EXCITED BY ULTRAVIOLET RADIATION WITH THE EMISSION CHARACTERISTIC DEPENDING UPON THE PARTICULAR SELECTED RARE EARTH METAL ACTIVATOR.

Patent
15 Jul 1969
TL;DR: In this paper, a mix of LANTHANUM OXIDE, CALCIUM CARBONATE and CHROME OXide is used to produce a solid solution for the MAGNETO-HYDRO-DYNAMIC GENERATOR.
Abstract: A MIXTURE OF LANTHANUM OXIDE, CALCIUM CARBONATE AND CHROME OXIDE IS FIRED TO PRODUCE A SOLID SOLUTION WHEREIN A PERCENTAGE OF THE LANTHANUM IONS OF THE LANTHANUM OXIDE HAVE BEEN REPLACED BY CALCIUM IONS THIS SOLID SOLUTION IS THEN PULVERIZED AND MOLDED TO PRODUCE AND ELECTRODE OF HIGH ELECTRON CONDUCTIVITY ESPECIALLY APPROPRIATE FOR USE IN THE MAGNETO-HYDRO-DYNAMIC GENERATOR

Journal ArticleDOI
TL;DR: In this paper, a theoretical model involving the presence of an inner 4f shell was developed to explain the pressure dependence of the superconducting transition temperature of lanthanum and its anomalous behavior.

Journal ArticleDOI
01 Nov 1969-Talanta
TL;DR: Substantial amounts of Ag, Al, Au, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ho, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn and platinum metals can be tolerated.

Journal ArticleDOI
TL;DR: The structure factor of liquid lanthanum has been measured by neutron diffraction, and turns out to be strongly different from other liquid metals structure factors obtained hitherto as discussed by the authors, which is very interesting.


Journal ArticleDOI
TL;DR: In this article, the TBP molecules solvating the lanthanide thiocyanates and tributyl phosphate (TBP) were examined by infrared spectroscopy to determine the stability constants of the adducts.

Journal ArticleDOI
TL;DR: In this paper, a polystyrene sulphonate type cation-exchanger was used for the measurement of chemical equilibrium constants for the hydrolytic reactions of very dilute aqueous solutions of indium and lanthanum at constant ionic strength.

Journal ArticleDOI
TL;DR: In this paper, the authors describe a set of conditions for a CAS to achieve pH5.9×104, including the following: 0.5% EDTA 0.25% CAS 0.6ml, 0.7%ヘキサミン溶液,0.1%
Abstract: クロムアズロールS(以下CASと略記)とゼフィラミン(テトラデシル-トリメチル-ベンジル-アンモニウムクロライド)により微量のベリリウムを吸光光度定量した.ベリリウム 0.1~3μgを含む塩酸性溶液を水で10~15mlにうすめ,0.5% EDTA溶液1ml,0.25% CAS溶液 0.6mlを加え,7%ヘキサミン溶液でpH5.1に調節したのち水で25mlにうすめ,15分後,610mμで試薬ブランクを対照として吸光度を測定する.見かけの分子吸光係数は9.9×104である.5μgのフッ素が妨害する.1mgの銅,100μgのアルミニウムは0.1%リン酸ナトリウム溶液 1mlで,100μgのバナジウム(V)は,ゼフィラミン-バナジン酸の沈殿をろ過することにより除かれる.