Peculiarities of the synthesis and thermolysis of heterometallic coordination compounds used as precursors for nickelates of rare-earth elements

The influence of the solvent on the composition of solid products is investigated using the example of the interaction of rare-earth element (REE) nitrates, Ln(NO₃)₃, with square-planar complexes of nickel and Schiff bases, Ni(SB). The composition of solid products is determined by X-ray fluorescence analysis and elemental analysis. It is shown that from the labile Ln(NO₃)₃-Ni(SB) systems, individual heterometallic compounds can be obtained, moreover, if in systems there are complexes with more dentate Ni(mosalen) ligands, only binuclear heterocomplexes can be produced. In case of Ni(salen) ligand, the formation of trinuclear complexes is achieved by selecting the optimal solvent. Among the considered compounds, binuclear complexes are of special interest due to the possibility of their use as precursors of REE nickelates.     

Crystal structure of the cubic β<Subscript>ms</Subscript>-phase of a La<Subscript>1.82</Subscript>Bi<Subscript>0.18</Subscript>Mo<Subscript>2</Subscript>O<Subscript>9</Subscript> single crystal at 33 K

Single crystals of the cubic β_ms-phase of La_1.82Bi_0.18Mo₂O₉ have been characterized for the first time by precision X-ray diffraction at 33 K. The structure of a crystal determined at T = 33 K is identical to the structure studied at room temperature. It is confirmed that the La, Mo1, and O1 atoms deviate from their positions on the threefold axis in the high-temperature β-phase; part of lanthanum atoms is substituted by bismuth atoms, which are located on the threefold axis; part of the molybdenum atoms return to the position on the threefold axis.     

Additives for Carbon Monoxide Afterburning in Gases from Regeneration of a Cracking Catalyst without Noble Metals

Russian Journal of Applied Chemistry - Additives for diminishing the content of carbon monoxide in gases formed in regeneration of the cracking catalyst without noble metals were synthesized and...     

Catalytic Cracking of Cyclohexane and 1-Hexene Mixtures on Mono-, Bi-, and Tri-Zeolite Catalysts

Kinetics and Catalysis - The effects of temperature (540–640°C), weight hour space velocity (1.0–7.0 h–1), and steam : raw material ratios (0–2.5) on the yield of...     

Growth Anisotropy and Crystal Structure of Linear Conjugated Oligomers

Physics of the Solid State - The results of a study of the influence of the crystal structure features of organic linear conjugated oligomers on the trends of their crystallization from solutions...     

On the Toroidal Surfaces of Revolution with Constant Mean Curvatures

It is shown that the surface with a constant mean curvature encloses the extremal volume among all toroidal surfaces of given area. The exact solution for the corresponding variational problem is derived, and its parametric analysis is performed in the limits of high and small mean curvatures. An absence of smooth torus with constant mean curvature is proved, and the extremal surface is demonstrated to have at least one edge located on the outer side of the torus.     

Structural reasons for the nonlinear optical properties of KTi<Subscript>0.96</Subscript>Zr<Subscript>0.04</Subscript>OPO<Subscript>4</Subscript> single crystals

This paper reports on the results of the precision X-ray structural investigations of KTi_0.96Zr_0.04OPO₄ single crystals at room temperature. It is established that the incorporation of zirconium atoms into the structure of KTiOPO₄ (KTP) crystals does not lead to substantial changes in the framework structure and results only in an insignificant decrease in the scatter of the distances in the PO₄ tetrahedra and the formation of more symmetric (TiZr)O₆ octahedra as compared to the TiO₆ octahedra. However, the incorporation of zirconium atoms into the KTP structure is accompanied by the redistribution of the electron density in the crystal as a whole, so that the electron density increases in the region of the positions occupied by the potassium atoms. This changes the nonlinear optical properties of the given series of crystals, which are estimated from the intensity of the second harmonic generation signals.     

Features in atomic force microscopy studies of dielectric surfaces

To improve the accuracy of AFM measurements in air and the reproducibility of results, a clean room-based metrological facility has been designed and built. The main function of the facility is to control temperature and humidity in an operation zone in various combinations and to maintain them with high accuracy. Measurements under controlled conditions are particularly important for dielectric materials. It has been shown that special procedures allow one to avoid disturbances caused by static charges on the surface under study, i.e., to remove the already accumulated charge and prevent its appearance during experiments. The use of the proposed procedures makes it possible to adequately study the features of the dielectric surface relief at micro-and nanoscale levels.     

Synthesis and electrical properties of Aurivillius phases in the Bi<Subscript>2</Subscript>MoO<Subscript>6</Subscript>-Bi<Subscript>2</Subscript>VO<Subscript>5.5</Subscript> system

To search for new oxygen conductive phases, a series of Bi₂V_{1 ? x} Mo_xO_{5.5 + x/2} ceramic samples have been synthesized in which the extreme compositions Bi₂VO_5.5 (x = 0) and Bi₂MoO₆ (x = 1) are single-layer Aurivillius phases having ferroelectric properties and high ionic oxide conductivity. It is established that single-layer Aurivillius phases exist in the composition ranges 0 ≤ x ≤ 0.1 and 0.9 ≤ x ≤ 1. Additional phases with BiVO₄ and Bi₆Mo₂O₁₅ structures are found in the range 0.2 ≤ x ≤ 0.8. The presence of molybdenum stabilizes the orthorhombic β-Bi₂VO_5.5 phase at room temperature. The conductivity of solid solutions based on Bi₂VO_5.5 differs only slightly from that of pure bismuth vanadate. Conductivity of solid solutions based on Bi₂MoO₆ is half an order of magnitude higher than that of pure bismuth molybdate.     

Qualitative and quantitative contents of organic acids in multivitamin plant raw materials studied using various physicochemical methods

Russian Chemical Bulletin - The results of qualitative analysis of organic acids in multivitamin mixtures No. 1 and No. 2 are presented. The contents of malic, citric, and ascorbic acids were...