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Gadolinium implanted cerium oxide (Gd-CeO 2 ) nanocomposites is an important candidate which have unique hexagonal structure and high K- dielectric constant. Gd-CeO 2 nanoparticles were synthesized using hydrothermal method. X-ray diffraction (XRD) results showed that the peaks are consistent with pure phase cubic structure the XRD pattern also confirmed crystallinity and phase purity of the sample. Nanocrystals sizes were found to be up to 25 nm as revealed by XRD and SEM. It is suggested that Gd gives an affirmative effect on the ion influence behavior of Gd-CeO 2 . XRD patterns showed formation of new phases and SEM micrographs revealed hexagonal structure. Photoluminescence measurement (PL) reveals the systematic shift of the emission band towards lower wavelength thereby ascertaining the quantum confinement effect (QCE). The PL spectrum has wider broad peak ranging from 390 nm to 770 nm and a sharp one centered on at 451.30 nm which is in tune with Gd ions. In the Raman spectra showed intense band observed between 460 cm −1 and 470 cm −1 which is attributed to oxygen ions into CeO 2 . Room temperature ferromagnetism was observed in un-doped and Gd implanted and annealed CeO 2 nanocrystals. In the recent studies, ceria based materials have been considered as one of the most promising electrolytes for reduced temperature SOFC (solid oxide fuel cell) system due to their high ionic conductivities allowing its use in stainless steel supported fuel cells. CeO 2 having an optical bandgap 3.3 eV and n-type carrier density which make it a promising candidate for various technological application such as buffer layer on silicon on insulator devices. [ABSTRACT FROM AUTHOR]

Corrosion layers in some copper and bronze archaeological objects from Haft Tappeh archaeological site, southwest Iran, were studied. For this purpose, optical microscopy, scanning electron microscopy with energy dispersive X-ray microanalysis, micro- Raman spectroscopy and X-ray diffraction methods were applied to observe corrosion stratigraphy and their characteristics as well as identification of chemical composition and phase determination of different corrosion layers. Based on optical and electron microscopy, three different corrosion strata were identified in cross section of different metallic objects including various red, green, white-grey powdery and dark internal compact layers. Scanning electron microscopy with energy dispersive X-ray microanalysis on different corrosion layers revealed that Cu, Sn and Cl are the main elements in the chemical composition of different layers. Tin-rich phases were detected in white-grey and dark layers that may be formed because of the internal oxidation of tin as well as the decuprification (selective dissolution of copper) phenomena occurring during long-termburial period in the soil. Also, the XRD and micro-Raman spectroscopy results proved that the main corrosion products are nantokite (CuCl), copper trihydroxychlorides and copper oxides. The combination of these analytical methods allows us to explore the surface and internal corrosion layers of the archaeological copper and bronze samples, and major interest is on studying their chemistry, microstructural properties and corrosion stratigraphy. [ABSTRACT FROM AUTHOR]

Based on micro-Raman spectroscopy (μ-Raman), micro X-ray fluorescence spectrometry (μ-XRF), X-ray diffractometry (XRD) and optical microscopy, this paper presents the results of our analytical studies on the early Islamic pigments used in the Masjid-i Jame of Fahraj, central Iran. Our investigations showed that ultramarine blue and haematite were used as blue and red pigments, respectively. Moreover, huntite was identified as white pigment with which whewellite was associated as a degradation product. Interestingly, the black paint was identified to be mainly composed of black plattnerite mixed with mimetite, hydromorphite and galena. Our geological survey at the Darreh Zanjir mine, located 35 km west of Fahraj, suggested this mine to be a possible source for supplying the black plattnerite. Accordingly, black plattnerite is suggested to be most probably used as a pigment and not to have formed as a degradation product of lead-based pigments. [ABSTRACT FROM AUTHOR]

Highlights: [•] LIBS, Raman, FTIR and XRD techniques allowed to identify the red pigment as red ochre. [•] The proposed approach provided insights on the used pigments and painting techniques. [•] The red pigment of the plasters has been compared with local Cottanello red marble. [•] The use of local and poor materials in roman rural villa of Sabina has been confirmed. [ABSTRACT FROM AUTHOR]

In this work, we report the successful formation of MgO doped TiO2 nanocrystals (NCs) by simple wet-chemical method. The XRD exhibits a marginal decrease in the crystalline size of TiO2 nanosamples by the addition of MgO dopant. UV-Vis spectral analysis shows that the addition of MgO in TiO2 resulted in the red shift of the absorption edge. The optical energy band-gap and molecular vibrational analysis of doped nanosample was ascertained from pho-toluminescence (PL) and micro-Raman scattering technique respectively. HR-TEM analysis reveals that the substitution has sharply reduced the particle size of TiO2NCs. [ABSTRACT FROM AUTHOR]

Various crystallite size estimation methods were used to analyze X-ray diffractograms of spherical cerium dioxide and titanium dioxide anatase nanoparticles aiming to evaluate their reliability and limitations. The microstructural parameters were estimated from several integral breadth methods such as Scherrer, Monshi, Williamson–Hall, and their variants: (i) uniform deformation model, (ii) uniform strain deformation model, and (iii) uniform deformation energy density model. We also employed the size–strain plot and Halder–Wagner method. For this purpose, an instrumental resolution function of an Al2O3 standard was used to subtract the instrumental broadening to estimate the crystallite sizes and strain, and the linear regression analysis was used to compare all the models based on the coefficient of determination. The Rietveld whole powder pattern decomposition method was introduced for comparison purposes, being the best candidate to fit the X-ray diffraction data of metal-oxide nanoparticles. Refined microstructural parameters were obtained using the anisotropic spherical harmonic size approach and correlated with the above estimation methods and transmission electron microscopy images. In addition, μ-Raman spectra were recorded for each material, estimating the mean crystallite size for comparison by means of a phonon confinement model. [ABSTRACT FROM AUTHOR]

The influence of type of steel and immersion time on the formation of magnetite in corrosion processes was investigated. For that purpose, weathering (WS) and low carbon steels (CS) were submitted to total immersion tests in a 0.2M NaCl solution for three different immersion times. The rusts which stay bounded to the metal, called adherent rusts (AR), as well as the rusts which is loosely bounded and suspended in the solutions, called non-adherent rusts (NAR), were studied by several techniques and the characteristics of the magnetite were determined. In this way measurements of X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform (DRIFT), Raman micro-spectroscopy (μ-Raman) and Mössbauer spectrometry (MS) were carried out. Magnetite was detected in all AR and NAR of CS after 14 days of immersion, but detected neither in AR nor in NAR of WS. Differences in stoichiometry, lattice parameter and vibrational characteristics were found. A possible mechanism for inhibition of magnetite formation on WS is discussed. [ABSTRACT FROM AUTHOR]