S.N. Nesterenko

CeRu2Al10 with the YbFe2Al10 structure type

The structure of cerium diruthenium decaaluminium, CeRu2Al10, is characterized by seven crystallographic sites in space group Cmcm, viz. Ce in 4c, Ru in 8a, two Al atoms in 8g, two Al atoms in 8f and one Al atom in 8e. The structure can be interpreted as a stacking of alternating columns running along [001], each formed by only one type of Ru cuboid with composition RuAl6 or CeRuAl4.

Effect of microstructure on the stability of nanocrystalline tin dioxide ceramics

Powdered nanocrystalline tin dioxide has been prepared by two different methods: conventional hydrolysis of SnCl4 solution and the so-called criosol technique. The latter involves treatment of a sodium stannate solution by a cation exchange resin in the H+ form and subsequent freeze drying. The microstructure, composition, specific surface area and electrical properties of the samples were investigated. The application of the criosol technique was shown to result in stable nanoscale particles of tin dioxide. The sintered pellets obtained by this method are characterised by significantly higher values of the resistance in comparison to material prepared by the conventional technique.

Phase relationships in the Ce-Pd-In system

The interaction of cerium with palladium and indium was studied, and the 773°C isothermal section of the Ce-Pd-In phase diagram was plotted using physicochemical methods: X-ray powder diffraction, single-crystal X-ray diffraction, and electron probe microanalysis. The existence of 12 ternary intermetallic phases in the title system was confirmed, and three new phases were discovered. Crystal structure was determined for seven intermetallic compounds. A single-crystal X-ray diffraction study of CePdIn was carried out for the first time. A high-temperature phase CePdIn4 was found, and its crystal structure was solved.

Ce2Ru3Al15, an intermetallic compound of a new structure type

The title compound, dicerium triruthenium pentadecaaluminium, is a new intermetallic compound from the Al-rich region of the Ce–Ru–Al phase diagram. Two Ce atoms (6g and 2a sites of space group P63/mcm) are coordinated by 18 atoms, one Ru atom (12i site) and five Al atoms (12k, 12i, 12j, 12j and 12k sites) have 12 nearest neighbours each.

High temperature interactions in the Fe-Al-C system at 6 GPa pressure

Abstract Alloys in the Fe-Al-C system were prepared by quenching from 1800 K to 298 K at 6 GPa pressure. Phase relations were investigated under normal conditions by means of X-ray diffractometry, microprobe analysis and metallography. According to the results of the experiments, a scheme of phase relations in quenched alloys of the Fe-Al-C system was suggested over a full concentration range. One ternary compound (Fe 3 AlC), three high-pressure phases (FeAl 6 , Fe 7 C 3 and C diamond ) and several binary compounds (Al 4 C 3 , Fe 4 Al 13 , Fe 2 Al 5 , FeAl 2 , FeAl, Fe 3 Al and Fe 3 C) were identified.

Synthesis and crystal structure of a new ternary intermetallic compound Ce16Ru8+x In3-x (0 < x < 1.0)

A study of phase equilibria in the Ce-Ru-In ternary system showed the presence of a new ternary compound Ce16Ru8+xIn3−x, which exists in the range of 0 < x < 1.0. According to a single-crystal X-ray diffraction study of Ce16Ru8+xIn3−x (x = 0.29), this compound crystallizes in the tetragonal system and represents a new structural type: a = 11.8047(15) Å, c = 9.5464(13) Å, space group. P4/mbm, Z = 2, RF = 0.059, Rw = 0.124. A specific feature of this structure is the presence of short Ce-Ru distances (2.575(3)Å).

A new ternary indide, Ce20Pd36In67

The intermetallic compound, cerium palladium indide, Ce20Pd36In67, crystallizes in a new structure type in which atoms have significantly distorted polyhedra with coordination numbers CN 15–18 for Ce and CN 8–13 for Pd and In.

25-O-05-Benzene alkylation with alkanes over modified MFI catalysts

Publisher Summary This chapter discusses benzene alkylation with alkanes over modified MFI catalysts. It describes benzene alkylation with ethane, propane, and i-butane on acidic H-MFI zeolite with silicon dioxide/alumina (SiO 2 /A1 2 O 3 ) ratio of 104; mixed (H-MFI + Pt/CeO2) catalytic systems and Pt/H-MFI bifunctional catalysts with platinum content of 0.3%. In some of the experiments, hydride-forming metals (M) are added to the catalytic systems to ensure H 2 removal from the reaction zone. The conversion of alkanes and the selectivity to the products of direct addition is found to increase in the following order of catalytic systems: H-MFI 2 H 6 3 H 8 4 H 10 ; their alkylating ability is found to increase in the reverse order.

Composition and structure of the oxidation products of Mo-Pt alloys

A novel approach has been proposed for producing model catalysts via oxidation of molybdenum- platinum alloys. The effect of alloy composition on the structure and morphology of the oxidation products has been studied, and heat-treatment conditions have been optimized to achieve a uniform distribution of fine platinum particles in the resulting molybdenum oxide.

LaRhAl, La3Rh3Al4, and Ce5Rh5Al6 as a new family of ternary aluminides

The structures of three aluminides of similar composition are determined via X-ray diffraction. The structures consist of coordination polyhedra built of rhodium atoms that form alternating layers extending perpendicular to the short cell parameter. Compound Ce5Rh5Al6 is built of fragments of the structures of LaRhAl and La3Rh3Al4 in a ratio of 1: 1.