Se obtienen los calores de reaccion para la formacion de cristales mixtos en el sistema LAC2-YC2 de las mediciones de las presiones de equilibrio durante la carborreduccion. Los valores positivos de los calores de reaccion son consistentes con los estudios de difraccion de rayos X de los productos de reduccion carbotermica de los oxidos, donde la formacion de los cristales mixtos de dicarburos (La,Y)C2 fue solamente observada alrededor de las dos regiones por encima del 25 % mol decada uno de los componentes minoritarios. La composicion de los productos gaseosos de la hidrolisis de los cristales mixtos (La,Y)C2 corresponde a los productos de la hidrolisis de los dicarburos. No se detecto metano en muestras con bajo contenido de Yitrio. AbstractThe reaction heats for the mixed crystal formation in the LAC2-YC2 system were obtained from the equilibrium gas presures measured during the carboreduction. The low positive values of the reaction heats are consistent with the X-ray diffraction study of the carbothermal reduction products of the oxides, where the formation of the (La,Y)C2 dicarbide mixed crystals was only observed in the two side region up to 25 mol % of each of the minority components. The composition of the gaseous hydrolysis products of the (La,Y)C2 mixed crystals corresponds to the hydrolysis product of the dicarbide. No methane was detected for samples with low ythrium contents.
Abstract Messungen der Reaktionsenthalpien für die Mischkristallbildung im Titelsystem während der carbothermischen Reduktion von Oxidgemengen sowie röntgenographische Untersuchungen der Reaktionsprodukte zeigen, daß Bildung von (La,Y)C 2 ‐Mischkristallen nur in den beiden Randbereichen des Systems mit bis zu 25 mol‐% der jeweils im Unterschuß vorhandenen Komponente auftritt.
The reaction heats for the mixed crystal formation in the LaC 2 -YC 2 system were obtained from the equilibrium gas pressures measured during the carboreduction. The low positive values of the reaction heats are consistent with the X-ray diffraction study of the carbothermal reduction products of the oxides, where the formation of the (La, Y)C 2 dicarbide mixed crystals was only observed in the two side regions up to 25 mol.% of each of the minority components. The composition of the gaseous hydrolysis products of the (La, Y)C 2 mixed crystals corresponds to the hydrolysis products of the dicarbide. No methane was detected for samples with low yttrium contents.
Abstract Die Titelkomplexe (I) bis (IV) wurden durch Reaktion der entsprechenden Sc‐Salze mit benzolischen Lactamlösungen in Gegenwart von Triäthylorthoformiat dargestellt und durch TGA, DTA, IR‐Spektren, Leitfähigkeits‐ und Molgewichtsbestimmungen untersucht.
A method is suggested for the indirect determination of cerium(III) ions in the presence of a high excess of tetravalent cerium. Ce(III) is oxidized to Ce(IV) by tris(1,10-phenanthroline)iron(III) complex (ferriin) in the presence of sodium diphosphate, and the purple-red iron(II) complex (ferroin) formed is determined photometrically at 530 nm. Trivalent cerium can be so determined in quantities of 0-400 μg/50 ml with a relative error of ±3.5%. Cerium(III) was determined in commercial cerium(IV) sulphate and cerium dioxide preparations.
Abstract CeUII) wird mit Ferriin in Gegenwart von Natriumdiphosphat zu Ce(IV) oxidiert und der entstandene Fe(II)‐Komplex (Ferroin) photometrisch bei 530 nm bestimmt.
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