다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

The surface and materials science of tin oxide

Although known since the late 19th century, organic–inorganic perovskites have recently received extraordinary research community attention because of their unique physical properties, which make them promising candidates for application in photovoltaic (PV) and related optoelectronic devices. This review will explore beyond the current focus on three-dimensional (3-D) lead(II) halide perovskites, to highlight the great chemical flexibility and outstanding potential of the broader class of 3-D and lower dimensional organic-based perovskite family for electronic, optical, and energy-based applications as well as fundamental research. The concept of a multifunctional organic–inorganic hybrid, in which the organic and inorganic structural components provide intentional, unique, and hopefully synergistic features to the compound, represents an important contemporary target.

Organic–Inorganic Perovskites: Structural Versatility for Functional Materials Design

Magnetism and Magnetic Materials

Nasicons (sodium super ion conductors) are a class of solid electrolytes. Their structure, compositional diversity, evolution, and applications are reviewed. A wide range of materials is considered based on crystalline and glassy Nasicon compositions.

A wide-ranging review on Nasicon type materials

Publisher Summary This chapter examines tin-antimony oxide catalyst which has been commercially developed for the oxidation of propylene to acrolein as well as for the ammoxidation of propylene to acrylonitrile and the oxidative dehydrogenation of butenes to 1,3-butadiene. The tin-antimony oxide catalyst is one that is most amenable to investigation by a wide range of spectroscopic and physical techniques. The properties of the system are very sensitive to composition, calcination temperature, and length of treatment. It is shown in the chapter that the coprecipitated catalyst is an initially homogenous and amorphous solid, which is slowly crystallized on heating. It seems that the range of compositions which give rise to the formation of solid solutions is small and only occurs when the materials are heated to high temperatures. The cationic species in the solid solution phase of antimony in tin oxide appear to be antimony and charge balance seems to be achieved by the delocalization of electrons into a conduction band.

Tin-Antimony Oxide Catalysts

Iron-zirconium oxides: An investigation of structural transformations by X-ray diffraction, electron diffraction, and iron-57 Mössbauer spectroscopy

In this paper we report the successful incorporation of silicon into SrFeO3−δ perovskite materials for potential applications as electrode materials for solid oxide fuel cells. It is observed that Si doping leads to a change from a tetragonal cell (with partial ordering of oxygen vacancies) to a cubic one (with the oxygen vacancies disordered). Annealing experiments in 5% H2/95% N2 (up to 800 °C) also showed the stabilization of the cubic form for the Si-doped samples under reducing conditions, suggesting that they may be suitable for both cathode and anode applications. In contrast to the cubic cell of the reduced Si doped system, reduction of undoped SrFeO3−δ leads to the formation of a brownmillerite structure with ordered oxide ion vacancies. SrFe0.90Si0.10O3−δ and SrFe0.85Si0.15O3−δ were analysed by neutron powder diffraction, and the data confirmed the cubic cell, with no long range oxygen vacancy ordering. Mossbauer spectroscopy data were also recorded for SrFe0.90Si0.10O3−δ, and indicated the presence of only Fe3+ and Fe5+ (i.e. disproportionation of Fe4+ to Fe3+ and Fe5+) for such doped samples. Conductivity measurements showed an improvement in the conductivity on Si doping. Composite electrodes with 50% Ce0.9Gd0.1O1.95 were therefore examined on dense Ce0.9Gd0.1O1.95 pellets in two different atmospheres: air and 5% H2/95% N2. In both atmospheres an improvement in the area specific resistance (ASR) values is observed for the Si-doped samples. Thus the results show that silicon can be incorporated into SrFeO3−δ-based materials and can have a beneficial effect on the performance, making them potentially suitable for use as cathode and anode materials in symmetrical SOFCs.

/pdf/investigation-into-the-effect-of-si-doping-on-the-49143bnnbu.pdf

Investigation into the effect of Si doping on the performance of SrFeO3−δ SOFC electrode materials

The synthesis and structural characterization of Sr2CuO4−x, x ∼ 0.1

We report here on the characterization of the vacancy-ordered perovskite-type structure of BaFeO2.5 by means of combined Rietveld analysis of powder X-ray and neutron diffraction data. The compound crystallizes in the monoclinic space group P2(1)/c [a = 6.9753(1) A, b = 11.7281(2) A, c = 23.4507(4) A, β = 98.813(1)°, and Z = 28] containing seven crystallographically different iron atoms. The coordination scheme is determined to be Ba7(FeO4/2)1(FeO3/2O1/1)3(FeO5/2)2(FeO6/2)1 = Ba7Fe([6])1Fe([5])2Fe([4])4O17.5 and is in agreement with the (57)Fe Mossbauer spectra and density functional theory based calculations. To our knowledge, the structure of BaFeO2.5 is the most complicated perovskite-type superstructure reported so far (largest primitive cell, number of ABX2.5 units per unit cell, and number of different crystallographic sites). The magnetic structure was determined from the powder neutron diffraction data and can be understood in terms of "G-type" antiferromagnetic ordering between connected iron-containing polyhedra, in agreement with field-sweep and zero-field-cooled/field-cooled measurements.

/pdf/crystallographic-and-magnetic-structure-of-the-perovskite-52wek2r6ol.pdf

Frank J. Berry

Papers

Tin-Antimony Oxide Catalysts

Iron-zirconium oxides: An investigation of structural transformations by X-ray diffraction, electron diffraction, and iron-57 Mössbauer spectroscopy

Investigation into the effect of Si doping on the performance of SrFeO3−δ SOFC electrode materials

The synthesis and structural characterization of Sr2CuO4−x, x ∼ 0.1

Crystallographic and magnetic structure of the perovskite-type compound BaFeO2.5 : unrivaled complexity in oxygen vacancy ordering