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Showing papers on "Lanthanum published in 1983"


Journal ArticleDOI
TL;DR: In this article, the properties of hot-pressed lanthanum-modified PbTiO/sub 3/ ceramics were measured as a function of crystal tetragonality.
Abstract: Dielectric, electromechanical, optical, and mechanical properties of hot-pressed lanthanum-modified PbTiO/sub 3/ ceramics were measured as a function of crystal tetragonality, c/a, in a range of tetragonal-to-cubic phases. The results obtained in this study are summarized as follows: The c/a changes linearly as a function of lanthanum content. Similarly, Curie point changed linearly and remanent polarization, coercive field, and coupling factors decreased with decreasing c/a. The sample with c/a = 1,010 showed the maximum transmittance of 61% wavelengths above 600 nm. The internal stress measured using the microindentation technique decreased with decreasing c/a in the tetragonal region and was zero in the cubic region.

98 citations


Journal ArticleDOI
TL;DR: In this article, high resolution electron microscopy and electron diffraction of several oxidized samples of the calcium lanthanum ferrites Ca x La 1− x FeO 3− y, with different values of x and y, prepared at high temperatures in air, shows the existence of a microdomain texture in which brownmillerite-type microdomains with a volume of ∼10 6 A 3 are intergrowth within a Ca 2 LaFe 3 O 8 substructure.

86 citations


Patent
Akira Kato1, Tomoichi Kamo1, Shigeo Uno1, Hiroshi Kawagoshi1, Hisao Yamashita1, Matsuda Shinpei1 
29 Nov 1983
TL;DR: A catalyst comprising precious metal particles supported on a carrier obtained from titania as a first component and as a second component at least one metal oxide selected from oxides of magnesium, strontium, lanthanum, yttrium, cerium, zirconium, silicon and tin, is effective for catalytic combustion of a fuel at a temperature of 400° to 1500° C. with excellent durability.
Abstract: A catalyst comprising precious metal particles supported on a carrier obtained from (a) titania as a first component and (b) as a second component at least one metal oxide selected from oxides of magnesium, strontium, lanthanum, yttrium, cerium, zirconium, silicon and tin, is effective for catalytic combustion of a fuel at a temperature of 400° to 1500° C. with excellent durability.

57 citations


Journal ArticleDOI
TL;DR: In this paper, four new ternary compounds with compositions Li6Nd(BO3)3, Na3Gd(Nd2O3), Na3La2(BO 3)2, Na18Nd-BO 3, and Na18La(BO 7)7 have been found in the M2ONd 2O3B2O 3 systems, where M is either Li or Na.

51 citations


Journal ArticleDOI
TL;DR: In this paper, the absorption spectra of new lanthanum aluminates LaMAl11O19 (M2+ = Ni, Co, Mn, Mg1−xMnx, 0 ≤ x ≤ 1), with magnetoplumbite-like structure have been obtained as single crystals.

42 citations


Journal ArticleDOI
TL;DR: A number of reduced oxides of molybdenum with lanthanum, neodymium, and yttrium in single crystal or oriented polycrystalline form are known as discussed by the authors.

37 citations


Journal ArticleDOI
TL;DR: In this article, a magnetoplumbite-type lanthanum aluminates with the formula LaMAl 11 O 19 (M 2+ = Ni 2+, Co 2+ ), Fe 2 +, Mg 1− x Mn x, 0≤ x ≤ 1, have been grown as large single crystals using the Verneuil process or the floating zone method.

37 citations


Journal ArticleDOI
01 Feb 1983-Talanta
TL;DR: Investigation of various physical and/or spectral interferences shows that good selectivity is obtained by ICPEDS.

29 citations



Journal ArticleDOI
TL;DR: The rare earth (RE) metals lanthanum, cerium, praseodymium, neodynium, samarium and samarium form hydrides REH≈233 and deuterides RED≈ 233 with a tetragonally distorted fluorite structure X-ray investigations show a facecentred tetragonal arrangement of the rare earth cations and a lattice parameter ratio c a > 1 Neutron diffraction studies of NdD236 yield a Tetragonal superstructure with c a ≥ 2 and space group I41md
Abstract: The rare earth (RE) metals lanthanum, cerium, praseodymium, neodymium and samarium form hydrides REH≈233 and deuterides RED≈233 with a tetragonally distorted fluorite structure X-ray investigations show a facecentred tetragonal arrangement of the rare earth cations and a lattice parameter ratio c a > 1 Neutron diffraction studies of NdD236 yield a tetragonal superstructure with c a > 2 and space group I41md The structure is related to the REH2 (CaF2) cell; some of the tetrahedral sites are vacant, but half or almost half of the octahedral sites are occupied by deuterium atoms in an ordered manner These results are compared with those of other workers

24 citations



Journal ArticleDOI
TL;DR: In this paper, physicochemical, spectroscopic, and lasing properties of lanthanum neodymium magnesium hexaaluminate single crystals were investigated, and it was found that concentration quenching of the luminescence was fairly weak in these crystals.
Abstract: An investigation was made of the physicochemical, spectroscopic, and lasing properties of lanthanum neodymium magnesium hexaaluminate single crystals It was found that concentration quenching of the neodymium luminescence was fairly weak in these crystals Lasing in these crystals was studied in the 106 μ range at 300 K Prospects for using hexaaluminate in laser technology are discussed

Patent
03 May 1983
TL;DR: In this article, the ratio by weight of inorganic oxide or oxides to yttrium or yttium combined with a rare earth metal or metals is from about 0.1 to about 30,000.
Abstract: Sulfur oxides are removed from a gas by an absorbent comprising at least one inorganic oxide selected from the group consisting of the oxides of aluminum, magnesium, zinc, titanium, and calcium in association with yttrium or yttrium combined with at least one free or combined rare earth metal selected from the group consisting of lanthanum, cerium, praseodymium, samarium, and dysprosium, wherein the ratio by weight of inorganic oxide or oxides to yttrium or yttrium combined with a rare earth metal or metals is from about 0.1 to about 30,000. Absorbed sulfur oxides are recovered as a sulfur-containing gas by contacting the spent absorbent with a hydrocarbon in the presence of a hydrocarbon cracking catalyst at a temperture from about 375° to about 900° C. The absorbent can be circulated through a fluidized catalytic cracking process together with the hydrocarbon cracking catalyst to reduce sulfur oxide emissions from the regeneration zone thereof.


Journal ArticleDOI
TL;DR: The borocarbide La 5 B 2 C 6 was prepared by melting lanthanum, boron and carbon in a high frequency furnace on a water-cooled copper hearth as discussed by the authors.
Abstract: The borocarbide La 5 B 2 C 6 was prepared by melting lanthanum, boron and carbon in a high frequency furnace on a water-cooled copper hearth. The crystal structure of the compound was determined by single-crystal X-ray analysis. The lattice parameters of the tetragonal cell (space group, P 4 ( C 1 4 , no. 75); Z = 4) are as follows: a = 8.585(3) A and c = 12.313(2) A . Intensity measurements were obtained using a four-circle diffractometer. The structure was solved by the Patterson method and was refined by full matrix least-squares calculations to R = 0.079 for 1305 unique structure factors. La 5 B 2 C 6 is isostructural with Ce 5 B 2 C 6 and undergoes a superconducting transition at 6.9 K.

Patent
25 Feb 1983
TL;DR: Lanthanum sulfide is maintained in the stable cubic phase form over a temperature range of from 500° C to 1500° C by adding to it small amounts of calcium, barium, or strontium.
Abstract: Lanthanum sulfide is maintained in the stable cubic phase form over a temperature range of from 500° C. to 1500° C. by adding to it small amounts of calcium, barium, or strontium. This novel compound is an excellent thermoelectric material.

Patent
23 Dec 1983
TL;DR: In this article, a low fired, temperature compensating dielectric composition is disclosed, which is formed of a base ceramic and a frit material, and includes magnesium oxide, titanium oxide, calcium oxide, alumina, silica and at least one oxide of a rare element from the group of niobium, neodymium, tantalum, lanthanum, yttrium and praseodmium.
Abstract: A low fired, temperature compensating dielectric composition is disclosed. The invention dielectric is formed of a base ceramic and a frit material. The base ceramic includes magnesium oxide, titanium oxide, calcium oxide, alumina, silica and at least one oxide of a rare element from the group of niobium, neodymium, tantalum, lanthanum, yttrium and praseodymium. The preferred oxides are those of niobium alone or with neodymium.

Journal ArticleDOI
TL;DR: A simple and rapid coprecipitation method for the determination of several trace metals in seawater is presented in this article, where the metals are coprecimitated with lanthanum hydroxide, the precipitate is dissolved, and then the metals were determined by atomic absorption spectrometry.
Abstract: A simple and rapid coprecipitation method for the determination of several trace metals in seawater is presented. These metals are coprecipitated with lanthanum hydroxide, the precipitate is dissolved, and then the metals are determined by atomic absorption spectrometry. Lanthanum hydroxide was chosen as a coprecipitant for the following reasons, (a) lanthanum hydroxide has a sufficiently low solubility and forms an easily filterable flocculate at about 80‡C, and (b) lanthanum has an absorption wavelength that is sufficiently separated from those of the other elements to be analysed, i.e., Mn, Fe, Ni, Cu and Zn. Experimental results show that these metals are coprecipitated by the present method with excellent recoveries.

Patent
12 May 1983
TL;DR: An aqueous acidic trivalent chromium electrolyte and process for electrodepositing chromium platings is described in this paper, where an electrolyte containing trivalents chromium ions, a complexing agent, halide ions, ammonium ions and a reducing agent comprising an ion selected from the group consisting of scandium, yttrium, lanthanum, titanium, zirconium, hafnium, molybdenum, arsenic, selenium, tellurium, cerium, uranium, and tin present in an
Abstract: An aqueous acidic trivalent chromium electrolyte and process for electrodepositing chromium platings comprising an electrolyte containing trivalent chromium ions, a complexing agent, halide ions, ammonium ions and a reducing agent comprising an ion selected from the group consisting of scandium, yttrium, lanthanum, titanium, zirconium, hafnium, molybdenum, arsenic, selenium, tellurium, cerium, uranium, and tin present in an amount effective to maintain the concentration of hexavalent chromium ions formed in the bath at a level at which satisfactory chromium electrodeposits are obtained.


Journal ArticleDOI
TL;DR: An inductively coupled plasma atomic emission spectrometry method was developed to determine percent levels of aluminum, cobalt, lanthanum, and ruthenium in fresh, calcined, and spent alumina-based catalysts as mentioned in this paper.
Abstract: An inductively coupled plasma atomic emission spectrometry method was developed to determine percent levels of aluminum, cobalt, lanthanum, and ruthenium in fresh, calcined, and spent alumina-based catalysts. Catalysts were digested with 8% H/sub 2/SO/sub 4/ and 10% HCl. Replicate analyses of catalysts of known metals content revealed very good precision and accuracy, percent relative standard deviations for each metal being better than 2%. Results on catalysts are compared to flame atomic absorption spectrometry data for aluminum, cobalt, and ruthenium. Studies showed that no significant interferences existed. 7 tables.

Journal ArticleDOI
Yoshio Masuda1
TL;DR: The thermal decomposition of rare earth formate anhydrides in a flowing nitrogen atmosphere was studied systematically by means of thermogravimetry and differential thermal analysis.

Journal ArticleDOI
TL;DR: The binding of lanthanum to murine neuroblas‐toma cells (clone N1E‐115) was studied and results suggest that this binding is to sites closely related to muscarinic receptors in the cells.
Abstract: : The binding of lanthanum to murine neuroblas-toma cells (clone N1E-115) was studied by means of electron microscopy and x-ray microanalysis. Lanthanum bound only to cellular membranes, in a nonuniform manner. This lanthanum binding was reduced by pharmacological agents that affect muscarinic receptors of these cells or the function of the receptors. These results suggest that this binding of lanthanum is to sites closely related to muscarinic receptors in the cells.

Journal ArticleDOI
TL;DR: In this paper, a triclinic IPr2dtp-3L2 complex was synthesized, and its crystal and molecular structure has been determined by the X-ray diffraction method.
Abstract: The new complex indicated in the title has been synthesized, and its crystal and molecular structure has been determined by the X-ray diffraction method. The crystal was triclinic; space group P\bar1, Z=2, a=23.071(9), b=11.060(11), c=10.793(13) A, α=120.0(1), β=97.2(2), γ=88.9(2)°. The final R value for 5969 reflections is 0.047. The central lanthanum(III) atom is an octa-coordination and in a dodecahedron geometry, being coordinated with six sulfur atoms of three O,O′-diisopropyl dithiophosphate ligands (iPr2dtp), which span at three m edges, and with two oxygen atoms of both the N,N-dimethylacetamide ligands (dma) at both ends of the remaining m edge. The other [Ln(iPr2dtp)3L2]-type complexes, where Ln=La or Nd; L=dma or N,N-dimethylformamide, have also been obtained. The P=S double bond of the iPr2dtp ligand in the title complex is almost completely delocalized.

Journal ArticleDOI
TL;DR: In particular, le temps de relaxation diminue en raison inverse de la pression as discussed by the authors, i.e., the time of relaxation diminues due to inverse de the pression.
Abstract: Observation d'un unique pic de relaxation intense: le temps de relaxation diminue en raison inverse de la pression. Ce comportement contraire a tout ce qui a pu etre observe sur les relaxations connues, peut s'expliquer en considerant que la relaxation est due a un ion substitutionnel de lanthanide trivalent, compense soit par un ion de fluor en position d'interstitiel a mode mou, soit par un electron

Patent
04 May 1983
TL;DR: In this article, a mixed aluminum oxide with the following formula is defined: X.sup.sub.-x.sbsb.1.2.sub., X.sub.1 -y.sbb.2.sub., Y.sub.).
Abstract: A mixed aluminum oxide having the following formula: X.sup.1.sub.(x.sbsb.1.sub.-x.sbsb.2.sub.) X.sup.2.sub.(x.sbsb.2.sub.) M 1 .sub.(y.sbsb.1 -y .sbsb.2.sub.) M 2 .sub.(y.sbsb.2.sub.) Al.sub.(z.sbsb.1 -z .sbsb.2.sub.) M 3 .sub.(z.sbsb.2.sub.) O 19 wherein X 1 and X 2 , which can be the same or different, represent a metal selected from the group consisting of lanthanum, praseodymium, neodymium, samarium and gadolinium, provided that X 1 and X 2 are different when X 1 or X 2 represents lanthanum or gadolinium; M 1 and M 2 , which can be the same or different, each represent a metal selected from the group consisting of magnesium and divalent transition metals; M 3 represents a trivalent transition metal; x 1 represents a number from 0.8 to 1; y 1 represents a number from 0.7 to 1; z 1 represents a number from 10 to 12; x 2 represents a number from 0 to x 1 ; y 2 represents a number from 0 to y 1 ; and z 2 represents a number from 0 to 1; and wherein said mixed aluminum oxide has a single phase crystalline structure of the magnetoplumbite type. A process for producing the mixed oxide is also disclosed, as well as its applications to power lasers emitting in the infrared and to telecommunications by optical fibers.

Journal ArticleDOI
TL;DR: In this article, the substitution of the end-member oxides in the ternary sodium borosilicate system have included work on the replacement of SiO2 with combinations of La2O3 and TiO2, which after heat treatment resulted in leachable sodium borate and insoluble La 2O3-TiO2 ceramic phases.
Abstract: Studies on the substitution of the end-member oxides in the ternary sodium borosilicate system have included work on the replacement of SiO2 with combinations of La2O3 and TiO2 which after heat treatment resulted in leachable sodium borate and insoluble La2O3-TiO2 ceramic phases. Sensitivity to impurities during this phase decomposition is illustrated by the differences in physical properties, chemical resistance properties and structures of the insoluble phase when results obtained from melts from Pt/Rh or Al2O3 crucibles are compared. These materials exhibit after leaching interconnected pores with surface area of up to 217 m2 g−1 and pore radii ranging between 1.2 and 10.25nm with noteworthy alkali resistance of up to 0.08×10−2 mg dm−2 Na2O mg calculated on the whole surface area of the samples.

Journal ArticleDOI
TL;DR: In this article, the determination of lead by electrothermal atomic absorption spectrometry was investigated for 30 different borehole and surface water samples by using direct, standard addition and lanthanum matrix modification procedures.

Journal ArticleDOI
TL;DR: Lanthanum does indeed have a postsynaptic action in addition to its prejunctional action in insect muscle fibres, and external recording of MEPSPs showed that adding lanthanum to the bathing medium increased the time constant of decay of the potential.
Abstract: The effect of extracellular lanthanum on neuromuscular transmission was studied in cockroach leg muscle and larval mealworm ventral muscle by means of microelectrodes. Miniature excitatory postsynaptic potential (MEPSP) frequency was markedly increased after lanthanum was added, in the presence and absence of calcium. The potentiation by La3+ was suppressed in a high Ca2+ saline and enhanced in the absence of Ca2+. Lanthanum ions blocked neuromuscular transmission at a concentration as low as 0.1 mM. The quantal content estimated by the failure method was reduced by 80% in the presence of 0.1 mM-La3+. The reduction in the EPSP amplitude by La3+ may be due to a decrease in the amount of transmitter released by a nerve impulse. The response to L-glutamate applied iontophoretically was also reduced in the presence of La3+. It seems unlikely that La3+ and L-glutamate were competing for a common binding site on the postsynaptic membrane since the apparent maximum of the dose-response curve for glutamate-induced depolarization was reduced in the presence of La3+. External recording of MEPSPs showed that adding lanthanum to the bathing medium increased the time constant of decay of the potential. These results suggest that lanthanum does indeed have a postsynaptic action in addition to its prejunctional action in insect muscle fibres.

Journal ArticleDOI
TL;DR: In this paper, the determination of cerium, lanthanum, neodymium, and praseodmium at major and minor levels in nickel- and iron-base hydriding alloys by inductively coupled plasma (ICP-AES) atomic emission spectrometry is investigated.