Preparation,crystal structure,and magnetic properties of β-Li3TiF6 = LiLi(TiF6)(TiF6)2 – a double fluoride?

Purple colored single crystals of the β-modification of Li₃TiF₆ have been prepared by heating an appropriate mixture of LiF and TiF₃ at 820°C under an argon atmosphere. β-Li₃TiF₆ crystallizes in C2/c with a = 14.452(2) Å, b = 8.798(1) Å, c = 10.113(1) Å and β = 96.30(1)º. The structure is isotypic to β-Li₃VF₆ and contains isolated compressed TiF₆ octahedra (d_Ti–F = 1.91–2.01 Å). Magnetic properties of β-Li₃TiF₆ were studied and discussed. Band structure calculations and calculations of the Madelung part of the lattice energy, MAPLE, were performed to discuss the chemical bonding.     

Preparation, Structure, and Properties of V2GeO4F2—Chains of VO4F2 Octahedra in the First V(III) Metallate Fluoride

Powder samples of the new oxide fluoride V₂GeO₄F₂ have been obtained by the reaction of appropriate amounts V₂O₃, VF₃, and GeO₂ at 700°C for 18 h in an argon-filled sealed platinum tube. V₂GeO₄F₂ crystallizes in the space group Pnma with a=9.336(1), b=8.898 (1), and c=4.912 (1) Å. The structure has been refined from X-ray powder diffraction data using the Rietveld method (R_int=5.5% and R_p=9.8%). The structure of V₂GeO₄F₂ exhibits close packed layers of the anions with an ordering of O and F. The characteristic building units are discrete GeO₄ tetrahedra with Ge-O distances of 1.75-1.80 Å. The V are coordinated by four O and two F to form VO₄F₂ octahedra connected via two common edges to give zigzag chains. These chains are linked via corners to form a three-dimensional network. The temperature dependence of the magnetic susceptibility of V₂GeO₄F₂ indicates antiferromagnetic correlations.     

A nonlinear Picone’s identity and its applications

The purpose of this note is to show a generalization to Picone’s identity in a nonlinear framework. The classical Picone’s identity turns out to be a particular case of our result. We show, as an application of our results, that the Morse index of the zero solution to a semilinear elliptic boundary value problem is 0 and also establish a linear relationship between the components of the solution of a nonlinear elliptic system.     

Neutron diffraction studies on Ca1−x Ba x Zr4P6O24 solid solutions

Herein we report the results of detailed crystallographic studies of Ca_1−x Ba _x Zr₄P₆O₂₄ compositions from combined Rietveld refinements of powder X-ray and neutron diffraction data. All the studied compositions crystallize in rhombohedral lattice (space group R-3 No. 148). A continuous solid solution is concluded from the systematic variation of unit cell parameters. The variation of unit cell parameters with the composition indicates decreasing trend in a parameter with increasing Ba2+ concentration contrast to an increasing trend in c parameter.      

Exergy and thermoeconomic analysis of cream pasteurisation plant

Journal of Thermal Analysis and Calorimetry - Cream is a milk derivative comparatively rich in fat, present in the form of emulsion of fat in skimmed milk, and acquired by physical extraction from...     

Metal-free intramolecular cyclopropanation of alkenes through iodonium ylide methodology

Intramolecular cyclopropanation of alkenes occurs thermally with iodonium ylides in the absence of conventional metal catalysts such as Rh(II) and Cu(II). In rigid molecular systems conversions are near quantitative. A mechanism is proposed involving formal 2+2 cycloaddition followed by reductive elimination of PhI to yield the cyclopropane.     

Surface treatment of nanoporous silicon with noble metal ions and characterizations

A very large surface to volume ratio of nanoporous silicon (PS) produces a high density of surface states, which are responsible for uncontrolled oxidation of the PS surface. Hence it disturbs the stability of the material and also creates difficulties in the formation of a reliable electrical contact. To passivate the surface states of the nanoporous silicon, noble metals (Pd, Ru, and Pt) were dispersed on the PS surface by an electroless chemical method. GIXRD (glancing incidence X-ray diffraction) proved the crystallinity of PS and the presence of noble metals on its surface. While FESEM (field emission scanning electron microscopy) showed the morphology, the EDX (energy dispersive X-ray) line scans and digital X-ray image mapping indicated the formation of the noble metal islands on the PS surface. Dynamic SIMS (secondary ion mass spectroscopy) further confirmed the presence of noble metals and other impurities near the surface of the modified PS. The variation of the surface roughness after the noble metal modification was exhibited by AFM (atomic force microscopy). The formation of a thin oxide layer on the modified PS surface was verified by XPS (X-ray photoelectron spectroscopy).