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Abstract Two rare earth monosilicates (Yb 2 SiO 5 , and Lu 2 SiO 5) were deposited using a low-cost coating application method to produce a single-layer coating. RE- oxides slurries were dip coated on oxidised CMC samples and subsequently heat treated at high temperature to ensure reaction between SiO 2 and RE-oxides to form the RE-monosilicate. A single, continuous, homogeneous thick coating of 25 μm was obtained. X-ray diffraction (XRD) confirmed formation of, RE-monosilicates in Yb and Lu silicate systems. Coated samples were exposed to 90% H 2 O static steam environment at 1350 °C for 25, 50, 100, and 150 h. Scanning Electron Microscopy (SEM) indicated that both coatings adhered strongly to the substrate. Coating thickness reduced from 22 μm to 11 μm for Yb-coating and 13 to 4 μm for Lu-coating with increasing corrosion time from 25 to 150 h, however there was no significant attack of the CMC for all steam exposure times. [ABSTRACT FROM AUTHOR]

Water vapour corrosion resistance of five rare earth monosilicates Y 2 SiO 5 , Gd 2 SiO 5 , Er 2 SiO 5 , Yb 2 SiO 5 , and Lu 2 SiO 5 was investigated during testing at 1350 °C for up to 166 h in static air with 90% water vapour. Four of the RE-silicates showed little weight gain (0.859 mg cm −2 ) after 166 h of exposure. Prior to testing the microstructure consists of equiaxed grains of 4- 7±0.4 µm. XRD analysis showed that after 50 h exposure to water vapour corrosion Y, Er, Yb and Lu-silicates had both mono and disilicates present on their surfaces as a result of the reaction between monosilicate and water vapour to form disilicate, while Gd-silicate has converted completely to G 4.67 Si 3 O 13 making it less stable for environmental barrier coating application. The microstructures of corroded Y, Er, Yb and Lu-silicates contain ridges and cracks, while that of Gd-silicate contains rounded grains suggesting melting along with striped contract grains. [ABSTRACT FROM AUTHOR]

The present paper reports local atomic structure investigation of novel AlFeCuCrMg x (x=0.5, 1, 1.7) high entropy alloys (HEAs) produced by mechanical alloying using Fe, Cr and Cu K-edge X-ray absorption near edge spectroscopy (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopy. XANES spectra measured at Fe and Cr K-edges resemble that of the respective pure metal foils, while the spectrum measured at Cu K-edge manifests the presence of some other phases in the as-milled alloys. The radial distribution functions (RDFs) obtained from Fourier transformation of EXAFS spectra support the formation of disordered BCC structure. [ABSTRACT FROM AUTHOR]

CuO is considered as an excellent candidate for numerous applications including in optical and electronic devices because of its unique physical properties such as low resistivity, oxygen vacancy mediated room temperature ferromagnetism, and low bandgap. Here, the role of additional Mn doping on the electronic and magnetic properties of Cu 0. 945 Fe 0.055- x Mn x O has been investigated. Le Bail profile analysis of x-ray diffraction data emphasizes on the single-phase monoclinic C 2/ c symmetry for all samples. The Mn addition in Cu 0. 945 Fe 0.055 O modifies the magnetic properties. Highest saturation moment is observed for x = 0.012 sample. X-ray absorption studies hint at a proper substitution of Mn4+ and Fe3+ ions in CuO and emphasize on the intrinsic origin of ferromagnetism in all the samples. [ABSTRACT FROM AUTHOR]

Abstract Single phase Co/Ni substituted CeO 2 nanoparticles reveal the importance of oxygen vacancies on the electronic properties of the materials. The effect of Co/Ni substitution on the structural, optical, and photoluminescence properties of CeO 2 have been studied systematically. Lattice shrinks and hence strain increase owing to incorporation of Co/Ni in CeO 2. Optical absorption analysis shows a red shift in band-gap with Co/Ni substitution. Photoluminescence studies reveals increase in defect concentration which causes quenching of PL emission. Vibration modes at ~460 cm−1 in Raman spectra indicates incorporation of Co/Ni in CeO 2 lattice whereas a broad peak appearing at ~ 540–640 cm−1 with substitution depicts the defects related to the increase in oxygen vacancy. X-ray absorption (XAS) studies show that Co/Ni substitution maintains local structure while Ce4+ → Ce3+ concentration increases to preserve the charge neutrality in lattice. [ABSTRACT FROM AUTHOR]