Showing papers on "Cerium published in 1969"
TL;DR: In this paper, the Anderson model for the $4{f}^{1}$ configuration of cerium was performed, taking into account combined spin and orbit exchange scattering, and the resultant interaction Hamiltonian differs qualitatively from the conventional $s\ensuremath{-}f$ exchange interaction.
Abstract: Starting with the Anderson model for the $4{f}^{1}$ configuration of cerium, the transformation of Schrieffer and Wolff is performed, taking into account combined spin and orbit exchange scattering. The resultant interaction Hamiltonian differs qualitatively from the conventional $s\ensuremath{-}f$ exchange interaction. The Kondo effect, the spin-disorder resistivity, the Ruderman-Kittel interaction, and the depression of the super-conducting transition temperature with impurity concentration are worked out for alloys containing cerium impurities on the basis of this new interaction.
539 citations
TL;DR: In this article, the optical properties of cerium-activated garnet crystals have been investigated, and the wavelength maxima of the fluorescence-spectrum profiles are found to be host-dependent.
Abstract: The optical properties of cerium-activated garnet crystals have been investigated. In the garnet crystals showing luminescence, a bright-yellow fluorescence has been observed. The fluorescence exhibits structure at low temperatures, and the wavelength maxima of the fluorescence-spectrum profiles are found to be host-dependent. Energy transfer has been observed from the cerium ion to the neodymium ion.
153 citations
TL;DR: Cerium orthoferrite (CeFeO3) was prepared by the reaction 3CeO2 + Fe2O3 + Fe → 3ceO3 as mentioned in this paper.
61 citations
51 citations
45 citations
TL;DR: In this article, Oximes and semicarbazones are oxidized by ceric ammonium nitrate to the parent carbonyl compound in good yield, and suitable solvent systems include aqueous alcohols, acetonitrile, and acetic acid.
Abstract: Oximes and semicarbazones are oxidized by ceric ammonium nitrate to the parent carbonyl compound in good yield. Suitable solvent systems include aqueous alcohols, acetonitrile, and acetic acid. The...
45 citations
TL;DR: In this paper, the electrical resistivities as a function of temperature (−130° to 25°C) were determined on single crystals of cerium hydride ranging in composition from CeH1.9-CeH2.7.
Abstract: Electrical resistivities as a function of temperature (−130° to 25°C) were determined on single crystals of cerium hydride ranging in composition from CeH1.94–CeH2.85. Measurements were performed in an inert‐atmosphere dry box using the four‐point probe technique. Cerium hydride exhibited metallic behavior in the range CeH1.9–CeH2.7. However, at a composition of about CeH2.85, a positive temperature coefficient of conductivity indicative of semiconductivity was observed. It is proposed that the semiconductivity of cerium trihydride is due to hydrogen vacancies which act as electron donors in the CeH3 structure. The observed change in slope of the resistivity vs 1 / T curves yielding two apparent activation energies is caused by the presence of substitutional oxygen impurities which act as electron acceptors. On the basis of this model, the donor level is calculated to be 0.30 eV below the conduction band.
44 citations
TL;DR: A new monoclinic phase of cerium orthovanadate, CeVO4(H), was found during the course of oxidation of pseudo-perovskite CeVO3 below 400°C.
Abstract: A new monoclinic phase of cerium orthovanadate, CeVO4(H), was found during the course of oxidation of pseudo-perovskite CeVO3 below 400°C. It has been confirmed to crystallize in the huttonite-type structure (C2h5−P21⁄n), that of LaVO4. The lattice parameters were determined to be:a0=6.98A, b0=7.22A, c0=6.76A, β=105°02′, V=328A3 and Z=4.This phase was metastable, and exothermally transformed into a known stable CeVO4 (tetragonal zircon-type, D4h19−I41⁄amd) above 400°C, releasing a small amount of oxygen. From magnetic, chemical and thermogravimetric analyses, the valences of cerium ion and vanadium ion in CeVO4-(H) seem to be tripositive and pentapositive respectively, but V4+ ion is mixed in zircon-type CeVO4; CeVO4(Z).
38 citations
32 citations
TL;DR: Praseodymium, under very high pressures, shows a magnetic behavior similar to that of cerium at normal pressure.
Abstract: Praseodymium, under very high pressures, shows a magnetic behavior similar to that of cerium at normal pressure.
29 citations
TL;DR: In this paper, the preparation of a new inorganic ion exchanger with the formula Ce(HAsO4)2·2H2O is reported This material is obtained as a yellow microcrystalline powder and is very stable to hydrolysis Its ion exchange capacity for Li+ and Na+ is 4·35 meq/g.
TL;DR: A mass-spectrographic investigation of the reaction MO2(g)⇄MO(g)+ 12O2 yielded values of ΔHo2000 = 73.5±2.
TL;DR: The ternary system Ce-C-N is complex. as discussed by the authors showed evidence of substitutional replacement of C22− by N3−, with a significant composition range.
TL;DR: All the elements studied were partly volatilised, even at low ashing temperatures, for this reason wet ashing is recommended for the determination of radioactive contaminants in biological material.
Abstract: The mollusc Mytillus galloprovincialis Lam. was allowed to take up radioisotopes of cerium, cobalt, manganese, protactinium, ruthenium and zinc from sea water. The loss of radioactivity when the molluscan soft tissues were heated to between 110° and 800° C in air was investigated. All the elements studied were partly volatilised, even at low ashing temperatures. For this reason wet ashing is recommended for the determination of radioactive contaminants in biological material.
Patent•
01 Apr 1969TL;DR: The positively charged fibrous cerium phosphates of this invention comprise colloidal fibrous crystalline cerium phosphate which contains at least 5 mole percent based on the number of moles of phosphorous of at least one +3 or +4 valent metal ion from the group of titanium, zirconium, hafnium, chromium, molybdenum, tungsten, manganese, aluminum, cobalt, cerium, the rare earths, thorium, tin and lead as mentioned in this paper.
Abstract: The positively charged fibrous cerium phosphates of this invention comprise colloidal fibrous crystalline cerium phosphate which contains at least 5 mole percent based on the number of moles of phosphorous of at least one +3 or +4 valent metal ion from the group of titanium, zirconium, hafnium, chromium, molybdenum, tungsten, manganese, aluminum, iron, cobalt, cerium, the rare earths, thorium, tin and lead.
Patent•
09 Jul 1969TL;DR: WATER SUSPENSIONS CONTAINING (I) a SILICATE OR MIXTURE of a SILCATE and COLLOIDAL SILICA and (II) a PHOSPAHTE of CERIUM, HAFNIUM, TIN, TITANIUM, OR ZIRCONIUM have been found to be stable WATER-INSOLUBLE FILMS or ION-EXchange MEMBERS can be made by removing the water from the SUSSENSIONS.
Abstract: WATER SUSPENSIONS CONTAINING (I) A SILICATE OR MIXTURE OF A SILICATE AND COLLOIDAL SILICA AND (II) A PHOSPAHTE OF CERIUM, HAFNIUM, TIN, TITANIUM, OR ZIRCONIUM HAVE BEEN FOUND TO BE STABLE WATER-INSOLUBLE FILMS OR ION-EXCHANGE MEMBERS CAN BE MADE BY REMOVING THE WATER FROM THE SUSPENSIONS
TL;DR: In this article, the magnetic heat capacity of pure cerium magnesium nitrate (CMN) and La-diluted CMN has been investigated and it has been shown that it may be possible to use the diluted salt as a refrigerant to 0.7 mK.
Abstract: We present measurements of the magnetic heat capacity of pure cerium magnesium nitrate (CMN) and La-diluted CMN. From the measurements, we conclude that it may be possible to use the diluted salt as a refrigerant to 0.7 mK.
TL;DR: The angular correlation of positron-annihilation radiation from cerium hydride was measured for hydrogen concentrations in the range H/Ce 1.8-2.8.
Abstract: The angular correlation of positron‐annihilation radiation from cerium hydride was measured for hydrogen concentrations in the range H/Ce = 1.8–2.8. The angular correlations were found to be broader than that from cerium metal and to increase in width with increasing hydrogen concentration in a manner consistent with the screened protonic model of the electronic structure. The anionic model does not provide a satisfactory explanation of the measured angular correlations.
TL;DR: In this paper, the vapor pressure of liquid cerium has been determined by combining mass effusion and mass spectrometric measurements to yield a vapor pressure equation: log 10 {p( Ce / atm }=(5500±0029)−(21070±55)K/T, (1525 to 2225K)
Patent•
07 Aug 1969TL;DR: A flying-spot scanner or a color television tube having indexing strips comprises a luminescent screen or indices of a substantially nonpersistent luminescing material consisting of yttrium silicate activated by trivalent cerium as mentioned in this paper.
Abstract: A flying-spot scanner or a color television tube having indexing strips comprises a luminescent screen or indexing strips of a substantially non-persistent luminescing material consisting of yttrium silicate activated by trivalent cerium.
TL;DR: In this paper, N-benzoyl-N-phenylhydroxylamine is recommended as a spectrophotometric reagent for cerium, which extracts cerium in the pH range 8-10.
TL;DR: In this article, the distribution of cerium(III), zirconium(IV), and plutonium(IV) was studied in systems where 3M nitric acid was the aqueous phase and a solution of tributyl phosphate and trilaurylammonium or triluylmethylammmonium nitrates in n -hexane or toluene was the organic phase.