Papers by Keyword: Solid Solution

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Authors: Shu Cai Zhou, Chen Guang Bai, Chun Lin Fu
Abstract: In order to reduce the oxidizing and volatilizing caused by Mg element in the traditional methods for synthesizing Mg2Sil-xSnx solid solutions, Mg2Sil-xSnx solid solutions have been prepared by Microwave-assisted Synthesis techniques. The heating behavior of Mg, Si and Sn fixed powder was investigated under microwave irradiation. X-ray diffraction (XRD) was used to characterize the powders. The results suggest that the temperature-rising rate is also dependent on the initial green density and higher green density provides lower heating rate while power setting are fixed. XRD patterns show that Mg2Sil-xSnx solid solutions have been well formed under microwave irradiation.
417
Authors: Frida Ulfah Ermawati, Suasmoro Suasmoro, Suminar Pratapa
Abstract: A study of liquid mixing route to synthesize high purity Mg0.8Zn0.2TiO3 nanopowder, a candidate dielectric ceramics, has been successfully performed. Formation of the phases on the dried powder was studied using TG/DTA, XRD and FT-IR data. Rietveld analysis on the collected XRD patterns confirmed the formation of solid solution in the system. Such solid solution can be obtained from the powder calcined at 500 °C, but calcination at 550 °C gave rise to the most optimum molar purity up to 98.5% without intermediate phases. The role of Zn ions on the formation of solid solution was also discussed. Homogeneity of particle size distribution and nano-crystallinity of the system was verified from the particle size analyzer data, TEM image and the Rietveld analysis output.
47
Authors: Frank Montheillet, David Piot
Abstract: The macroscopic strain rate sensitivity m and apparent activation energy Q are derived from their microscopic counterparts associated with strain hardening, grain boundary mobility, and nucleation rate in the case of steady state discontinuous dynamic recrystallization (DDRX). The case of solid solutions, involving effects of the solute concentration on strain hardening and boundary mobility, is also taken into consideration. Moreover, three distinct Derby exponents are introduced to refine the correlation between steady state flow stress and average grain size. Hot torsion data and micrographic observations on a set of nickel-niobium alloys are used to assess the predictions of this tentative approach.
2257
Authors: P. Hidalgo, C.M. Cepeda-Jiménez, Oscar A. Ruano, Fernando Carreño
Abstract: The 7075 Al alloy was processed by accumulative roll bonding (ARB) at 300, 350 and 400 °C. The microstructure and texture were characterized and the hardness was measured. Cell/(sub)grain sizes less than 500 nm and typical β-fibre rolling texture were observed in the three ARBed samples. At 400 °C, the presence of elements in solid solution leads to a poorly misoriented microstructure and to a homogeneous β-fibre texture. At 300 and 350 °C highly misoriented microstructure and heterogeneous β-fibre rolling texture are observed, especially at 350 °C, wherein the degree of dynamic recovery is higher. Hardness of the ARBed samples is affected by the amount of atoms in solid solution at the different processing temperatures.
1929
Authors: David Marchat, Didier Bernache-Assollant, Eric Champion, Eric Bêche, Gilles Flamant
Abstract: The removal of cadmium from water by fixation into a calcium phosphate apatite Ca10(PO4)6(OH)2 (CaHA) was investigated in batch experiments. These ones were carried out using a wide range of initial Cd2+ concentration, three different temperatures, and several CaHA surface areas. The amount of immobilized cadmium was proportional to the surface area of CaHA, whatever the experimental parameters might be. It could reach 7.1 mol of Cd per mol of starting CaHA. Thermal and XPS analyses on the exchanged powders proved that a part of cadmium was quickly adsorbed at the grains surface in the form of hydrated complexes [Cd(OH2)n]2+. The latter were formed by an ionic exchange between adsorbed calcium and cadmium of the solution. Adsorption reaction was mainly limited by the number of specific sites available on the grains surface. Structural analyses showed that another part of Cd was slowly incorporated into a solid solution Ca10-xCdx(PO4)6(OH)2 (CaCdHA) onto the CaHA crystals surface. Results demonstrated unambiguously that the incorporation process was a surface precipitation and not an intracrystalline diffusion.
2055
Authors: Katja Tonisch, Robert Benzig, Gernot Ecke, Jörg Pezoldt
Abstract: The growth of AlGaN solid solutions on 3C-SiC(111)/Si(111) is demonstrated. The residual stress of the grown layer was investigated by high resolution X-ray diffraction (HRXRD) and infrared ellipsometry. Analysis of the HRXRD data showed that the observed lattice distortion was caused partially by hydrostatic pressure and partially by biaxial tension. The residual stress depends on the layer composition and weakly on the growth temperature.
103
Authors: Masanori Hirano, Norio Kuno
Abstract: Composite nanoparticles (anatase-type Ti1-2XNbXAlXO2 solid solution/SiO2) were directly synthesized from precursor solutions in the presence of urea under mild hydrothermal conditions at 180 °C for 5 h. The crystallite size of anatase was gradually decreased with increased silica content in the composite nanoparticles formed under weakly basic hydrothermal conditions via the hydrolysis of urea. The composite nanoparticles with composition Ti0.9Nb0.05Al0.05O2/SiO2 = 100/10 mol% showed good photocatalytic activity. The anatase-to-rutile phase transformation in the course of heating in air was retarded to maintain the anatase-type structure up to more than 1050 °C without a trace of rutile phase by the formation of composite nanoparticles (Ti0.90Nb0.05Al0.05O2/SiO2 = 100/20 mol%) with amorphous silica.
2735
Authors: Leonid Vasylechko, Olha Pekinchak, Vasyl Hreb, Yurii Prots, Dmitry Chernyshov, Andrew Fitch
Abstract: Series of the mixed cobaltites-ferrites RCo1xFexO3 (x = 0.1–0.9) and cobaltites-chromites RCo0.5Cr0.5O3 (R = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er) with the orthorhombic perovskite structure (space group Pbnm) have been prepared from stoichiometric amounts of rare earth oxides, Co3O4, Fe2O3 and Cr2O3 by solid-state reaction in air at 1473–1573 K. In situ high-temperature X-ray synchrotron powder diffraction revealed anomalous lattice expansion of both series, which is reflected in a sigmoidal dependence of the unit cell dimensions and in abnormal anisotropic increase of the thermal expansion coefficients (TEC). Depending on the composition, several broad maxima in the temperature range of 500−1000 K are observed, which are evidently connected with the transitions of Co3+ cations to the higher spin states. The observed anomalies in the mixed cobaltites-ferrites and cobaltites-chromites are less pronounced compared with the corresponding “pure” cobaltites.
99
Authors: Jörg Pezoldt, Thomas Kups, Petia Weih, Thomas Stauden, Oliver Ambacher
Abstract: 3C-(Si1-xC1-y)Gex+y ternary alloys were grown on 8.5° off axis 4H-SiC substrates by solid source molecular beam epitaxy in a temperature range between 750°C and 950°C. Energy dispersive X-ray (EDX) analysis revealed a decrease of the Ge incorporation versus substrate temperature. This effect is due to the fixed Si/Ge ratio during the epitaxial growth. The Ge distribution within the grown epitaxial layers was found to be nearly homogeneous. The investigations by atomic location by channeling enhanced microanalysis allowed the conclusion that Ge is located mainly at Si lattice sites.
1559
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