Abstract: A study of the hydrogen sorption behaviour of several intermetallic compounds based on 3d metals (M) and cerium or yttrium (R) is reported. As well as pressure-composition isotherms, an X-ray diffraction study was made of the structural changes that accompany hydrogen absorption. It was found that, in compounds of the types R 2 M 7 and RM 3 , the structure type is preserved during hydrogen absorption. In yttrium compounds expansion occurs in the c direction as well as in the basal plane of the hexagonal or rhombohedral unit cells. In cerium compounds the expansion affects the c direction exclusively. This expansion is particularly large in CeCo 3 H 4 where, with respect to CeCo 3 , the c axis increases by more than 30%.

Abstract: A catalyst for purifying exhaust gas composed of a catalyst carrier coated with a metal oxide material containing a spinel metal oxide of the formula: MAl 2 O 4 wherein M is Sr, Mg, Cu, Mn, Mo, Zn, Fe, Co or Ni the metal oxide coated carrier further being coated with rhodium and platinum and/or palladium as catalytically active components The catalytically active components also can include cerium

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 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 rare earth metal or metals is from about 0.1 to about 30,000. Absorbed sulfur oxides are recovered as a sulfur-containing gas comprising hydrogen sulfide by contacting the spent absorbent with a hydrocarbon in the presence of a hydrocarbon cracking catalyst at a temperature 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.

Abstract: We studied the ternary phases of alloys of the rare earths with antimony and palladium in the stoichiometric ratio 1:1:1. The alloys with lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium and terbium proved to be of the hP6 CaIn2 type, whereas those with dysprosium, holmium, erbium, ytterbium and yttrium were of the cF12 MgAgAs type. The trends of the molar volumes are briefly discussed in relation to the molar volumes of isostructural compounds known already.

Abstract: Rare earth glass-polishing compositions of improved homogeneity and reproducibility are prepared by (a) simultaneously continuously admixing a cerium salt solution, a basic solution and a solution of at least one acid and/or one salt, the anion or anions of which being adopted to form insoluble rare earth compounds, the number of equivalents of base being equal to or greater than the number of equivalents of cerium, and the pH of the reaction medium being greater than about 6; (b) filtering the precipitate which reuslts from the reaction medium; (c) drying said recovered precipitate; and (d) calcining said dried precipitate.

Abstract: An alumina base catalyst carrier material which is thermally stable and possesses a high surface area consisting of a cerium oxide coating on active alumina granules. The carrier is prepared by the precipitation of cerium hydroxide from an aqueous slurry of the alumina granules also containing the water soluble salts of cerium.

Abstract: The (La 0.5 Ce 0.5 )Ni 5− x Co x -hydrogen system was studied using pressure-composition and X-ray diffraction techniques. The (La,Ce)Ni 5 compounds display very large hysteresis effects in the course of a hydrogenation cycle. The addition of cobalt markedly affects the absorption plateau pressure which reverts to normal values at x = 1, practically eliminating the hysteresis effect. The results indicate that the elevated absorption plateau pressure and the resulting hysteresis effect are due (1) to the presence of cerium atoms and (2) to the formation of the expanded H I LaNi 5 -type hydride. The formation of this greatly expanded hydride phase favours the reversion of cerium to the trivalent state. The substitution of 20% of the nickel atoms by cobalt atoms suppresses the formation of the H I hydride which is replaced by the less expanded H II hydride. The H II hydride does not display anomalous hysteresis effects.

Abstract: CeBe13 is thought to present an intermediate valence state at normal pressure. An interesting feature of this intermetallic compound is that the valence of cerium seems to vary with temperature. The results of an XPS study which confirms the coexistence of the two valence states of cerium (Ce3+(4f15d0); Ce4+(4f05d1)) in CeBe13 are presented. When the temperature is lowered down to 100K both the lattice parameter behaviour and the XPS spectra may be explained assuming a slight increase of the ratio Ce4+/Ce3+. In order to ensure the validity of the results, a comparison with other LnBe13 compounds is given. Electrical resistivity and susceptibility measurements on LnBe13 (Ln:La, Ce, Gd) are also discussed and this illustrates clearly the particular behaviour of CeBe13.

Abstract: The Fe(III)-Fe(II) and Ce(IV)-Ce(III) redox equilibria in CaMgAl-silicate glasses have been individually investigated as a function of base composition, melt temperature, imposed oxygen fugacity, and multivalent element concentration. The mutual interaction of these two redox couples has been studied in analogous glasses which simultaneously contained iron and cerium. The iron and cerium redox couples have been placed in a series of relative redox potentials for silicate glasses; in order of ease of reduction, Ce(IV)→Ce(III) > Fe(III)→Fe(II) > Cr(III)→Cr(II) > Eu(III)→Eu(II) >> Ti(IV)→Ti(III). In the glasses containing both iron and cerium, the Fe(II) ions are stoichiometrically oxidized by Ce(IV) ions to produce Fe(III) and Ce(III) ions, which form Ce(III)OFe(III) complexes.

Abstract: The synthesis of a new class of trimethylene bridged biscyclopentadienyl derivatives of lanthanum(III) and cerium(III) with chloride and pentyethynyl ligands is reported

Abstract: A silicon nitride based sintered product produced by sintering a powder mixture consisting essentially of silicon nitride, at least one oxide of yttrium, scandium, cerium, lanthanum and the metals of lanthanide series and at least one metal or metal oxide of iron, nickel and cobalt.

Abstract: The ZnO- or CdS-catalysed photocycloreversion of the strained cage molecule (1) afforded the diene (2), which was also produced by a cerium ammonium nitrate-catalysed dark reaction and by photoexcitation of the charge-transfer complex of (1) with tetracyano-ethylene.

Abstract: Terephthalic acid with a high purity and high whiteness is produced by oxidizing p-tolualdehyde with molecular oxygen such as air in the presence of a heavy metal catalyst of manganese and/or cerium, a bromine compound, and a mineral acid in water as a solvent at a bromine compound concentration of 0.5-12% by weight on the basis of the reaction solution in terms of bromine ions and at a ratio of g-equivalents of hydrogen ions of the mineral acid to sum total of g-equivalents of the hydrogen ions and manganese and/or cerium ions of 1-85% and at a ratio of sum total of g-equivalents of the hydrogen ions and manganese and/or cerium ions to g-equivalents of bromine ions of 0.5-5. Terephthalic acid thus produced is directly polymerizable with glycols without any purification.

Abstract: Losses of silver, cerium, caesium, manganese, scandium and tin during freeze drying and oven drying at 80, 105 and 120 °C were studied in rat tissues and faces that contained radioactive isotopes. No loss was observed for any of these elements on freeze drying. A significant loss of tin was observed in muscle even at 80 °C, and in kidney and liver at 105 °C. Also, cerium and manganese were lost from heart and muscle at this temperature. An increase in the temperature to 120 °C was found to be safe only for silver and caesium in all of the tissues. For the remaining four elements the following losses were observed: up to 5% for cerium in brain and heart, for scandium in fur and heart and for manganese in liver and muscle; up to 10% for scandium in kidney and muscle and for tin in blood, fur, heart, liver, ovary and uterus; and over 10% for tin in brain, kidney, lung and muscle.

Abstract: An excitonic insulator model is proposed for early rare earth hydrides in an attempt to explain the metal-semiconductor transition. Band structure calculations for the trihydrides of lanthanum and cerium demonstrate the reason for such a model. Two possible types of electron-hole coupling in these systems are discussed. It is shown that in the first case a dielectric state occurs. In the second case a semimetallic state remains but a supercell with twice the periodicity along one of the principal directions 〈111〉 together with rhombohedral distortion appears. The experimental results were analysed on the basis of an excitonic insulator phase diagram. The first type of electron-hole coupling is realized.

Abstract: 3d and 4d core-level XPS spectra for CePd3, a mixed-valence system, have been measured. Each spectrum exhibits two sets of structures, each corresponding to one of the valence states of cerium. Thus the usefulness of XPS, which has so far not been used extensively to investigate the mixed-valence cerium systems, is pointed out.

Abstract: Alkali metal delta manganese dioxide hydrate, which is obtained as a by-product in the industrial oxidation of organics by KMnO 4 is subjected to ion exchange reaction with rare earth ions of the ceria subgroup (viz. cerium, lanthanum, etc.). By employing favorable temperature and pH conditions, a reaction product can be produced containing as little as 0.03 moles of alkalii metal per mole of manganese, and up to one mole of ceria rare earth per six moles of manganese. The separated product is prepared for catalytic use in the form of dried porous pellets. The resulting oxidation catalyst has high efficiency, long life, and optimum activity at reasonable temperatures. The catalyst can be used advantageously for applications such as the oxidation and deodorization of exhaust gases from paint drying ovens.

Abstract: 1. Scandium increases the strength characteristics of the Al-6.5% Mg alloy, which is due to the unrecrystallized structure after hot extrusion and annealing. 2. Terbium, holmium, yttrium, lathanum, gadolynium, and cerium increase the strength characteristics slightly, while europium and dysprosium have almost no effect on the mechanical properties of the Al-6.5% Mg alloy.