X-ray diffraction (Materials Characterisation) Research Papers (original) (raw)

An archaeometric study has been conducted on the handmade pottery recovered at Sant Jaume by combining different analytical techniques (XRF, XRD, SEM). The results show that all ceramics were produced by using the same technical... more

An archaeometric study has been conducted on the handmade pottery recovered at Sant Jaume by
combining different analytical techniques (XRF, XRD, SEM). The results show that all ceramics were
produced by using the same technical tradition: a clay paste enriched with crushed calcite as temper,
fired at low firing temperatures. This tradition was used in all different ceramic types regardless of
their function. Moreover, several provenances have also been identified. Therefore, we propose the
existence of local and regional networks for handmade pottery production and distribution, something
that changes the nowadays assumption of local production.

Abstract: Nanophosphor β-Zn2SiO4:Mn with bright yellow light emission were synthesized by a sol–gel process. These samples were prepared by a simple solid-phase reaction under natural atmosphere at 1500 °C after the incorporation of... more

Abstract:
Nanophosphor β-Zn2SiO4:Mn with bright yellow light emission were synthesized by a sol–gel process. These samples were prepared by a simple solid-phase reaction under natural atmosphere at 1500 °C after the incorporation of ZnO:Mn nanoparticles, in silica monolith. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the phase purity, particle size and morphology. In addition photoluminescence (PL) was used for optical study. The PL spectrum for the β-Zn2SiO4:Mn nanophosphors showed a dominant peak at 574 nm, which originated from the 4T1 → 6A1 transitions of Mn2+ ions. The level of manganese doping did not greatly affect the crystallinity, but did affect the luminescence of nanophosphors. Upon 255 nm excitation, the luminescence decay time of the yellow emission of β-Zn2SiO4 with a Mn doping concentration of 2 at.% around 574 nm is 13 ms. The characteristics of crystallinity, morphology and luminescence property of the obtained nanophosphors were investigated.

Differential thermal analyses of glass frits with nominal molar composition 0.45SiO2–0.405MgO–0.045K2O–0.1(3CaO⋅P2O5) showed two main exothermic peaks. X-ray diffraction was used to ascribe these peaks to the crystallisation of a... more

Differential thermal analyses of glass frits with nominal molar composition 0.45SiO2–0.405MgO–0.045K2O–0.1(3CaO⋅P2O5) showed two main exothermic peaks. X-ray diffraction was used to ascribe these peaks to the crystallisation of a whitlockite related phosphate phase Ca9MgK(PO4)7 at temperatures close to 900°C and mainly forsterite (Mg2SiO4) at higher temperatures. The DTA phosphate peak was nearly independent of the particle size of frits and scanning electron microscopy suggests that Ca9MgK(PO4)7 crystallises in the bulk, mainly with plate like shape. The silicate peak was strongly dependent on the grain size suggesting surface crystallisation for the smaller particle sizes; this might be related to surface crystallisation of diopside in samples with small grain sizes as found by x-ray diffraction.

An investigation on the crystallisation of a whitlockite type orthophosphate phase in a calcium phosphosilicate glass frit with the molar composition (3CaO⋅P2O5)20(SiO2)35(MgO)38.354(K2O)6.646 was made. Isothermal heat treatments at... more

An investigation on the crystallisation of a whitlockite type orthophosphate phase in a calcium phosphosilicate glass frit with the molar composition (3CaO⋅P2O5)20(SiO2)35(MgO)38.354(K2O)6.646 was made. Isothermal heat treatments at different temperatures combined with XRD and SEM analysis of the glass ceramics have shown that in glass frits of this composition the whitlockite type orthophosphate phase, Ca9MgK(PO4)7 develops from earlier crystalline phosphate phase precursors, namely from oxyapatite (OAp), the ideal composition being Ca5(PO4)3O. This OAp phase seems to evolve from a previous tricalcium phosphate phase, Ca3(PO4)2 (TCP).

The three-dimensional microstructure of polycrystalline materials unravelled by synchrotron light Synchrotron radiation X-ray imaging and diffraction techniques offer new possibilities for non-destructive bulk characterization of... more

The three-dimensional microstructure of polycrystalline materials unravelled by synchrotron light Synchrotron radiation X-ray imaging and diffraction techniques offer new possibilities for non-destructive bulk characterization of polycrystalline materials. Minute changes in electron density (different crystallographic phases, cracks, porosities) can be detected using 3D imaging modes exploiting Fresnel diffraction and the coherence properties of third generation synchrotron beams. X-ray diffraction contrast tomography, a technique based on Bragg diffraction imaging, provides access to the 3D shape, orientation and elastic strain state of the individual grains from polycrystalline sample volumes containing several hundred up to a few thousand grains. Combining both imaging modalities allows a comprehensive description of the microstructure of the material at the micrometer length scale. Repeated observations during (interrupted) mechanical tests provide unprecedented insight into crystallographic and grain microstructure related aspects of polycrystal deformation and degradation mechanisms in materials, fulfilling some conditions on grain size and deformation state

In this study, a new method to synthesize neodymium doped ceria ceramic nanopowders by the electrospinning of the hybrid polymers solution of their composite precursor was put forward. Calcined and sintered nanopowders were characterized... more

In this study, a new method to synthesize neodymium doped ceria ceramic nanopowders by the electrospinning of the hybrid polymers solution of their composite precursor was put forward. Calcined and sintered nanopowders were characterized by FT-IR, XRD, BET, SEM, and AFM techniques. According to the XRD analysis, the obtained powders are single phase and independent of the dopant concentration in the range investigated. The crystallite sizes were calculated using Scherrer equation. Moreover, lattice parameters, dislocation densities and microstrain values were calculated. BET results show that the increase of the neodymium doped content decrease the surface area of the composite powders, confirming the highly ordered micro and mesostructure. SEM and AFM results show that the samples have spherical grains. According to the surface roughness measurements, the increase in the amount of neodymium and the decrease in the amount of cerium decreased the surface roughness.

a r t i c l e i n f o Available online xxxx Keywords: Nondestructive GaN Synchrotron X-ray diffraction Nano Nanowire RSM MQW Submicron beam synchrotron-based X-ray diffraction (XRD) techniques have been developed and used to accurately... more

a r t i c l e i n f o Available online xxxx Keywords: Nondestructive GaN Synchrotron X-ray diffraction Nano Nanowire RSM MQW Submicron beam synchrotron-based X-ray diffraction (XRD) techniques have been developed and used to accurately and nondestructively map chemical composition and material quality of selectively grown group III-nitride nanowires. GaN, AlGaN, and InGaN multi-quantum-well nanowires have been selectively grown on lattice matched and mismatched substrates, and the challenges associated with obtaining and interpreting submicron beam XRD results are addressed and solved. Nanoscale cathodoluminescence is used to examine exciton behavior, and energy-dispersive X-ray spectroscopy is used to verify chemical composition. Scanning transmission electron microscopy is later used to paint a more complete picture. The advantages of submi-cron beam XRD over other techniques are discussed in the context of this challenging material system.