Showing papers by "Andrew Bleloch published in 2010"
TL;DR: In this article, the effect of high-energy electron irradiation on ferritin/haemosiderin cores (in an iron-overloaded human liver biopsy), its mineral analogue; six-line ferrihydrite (6LFh), and iron phosphate dihydrate (which has similar octahedral ferric iron to oxygen coordination to that in ferri hydrite and Ferritin and Haemosidersin cores) has been investigated using electron energy-loss spectroscopy (EELS).
47 citations
TL;DR: Following the evolution of the magnetic domain pattern in the system, it is suggested that domain walls are pinned on structural inhomogeneities given by the underlying nanoperforated template.
Abstract: We present a study on the magnetization reversal in Co/Pt multilayer films with an out-of-plane easy axis of magnetization deposited onto substrates with densely distributed perforations with an average period as small as 34 nm. Deposition of magnetic Co/Pt multilayers onto the nanoperforated surface results in an array of magnetic nanodots surrounded by a continuous magnetic film. Following the evolution of the magnetic domain pattern in the system, we suggest that domain walls are pinned on structural inhomogeneities given by the underlying nanoperforated template. Furthermore, a series of micromagnetic simulations was performed in order to understand the modification of the pinning strength of domain walls due to the magnetic interaction between nanodots and the surrounding film. The results of the simulations show that magnetic exchange coupling between the nanodots and the surrounding film strongly influences the pinning behavior of the magnetic domain walls which can be optimized to provide maximal pinning.
37 citations
TL;DR: In this paper, an aberration-corrected electron microscopy is used to determine the chemical composition and structure of materials at atomic resolution, which enables the formation of angstrom sized electron probes that contain enough current for both low loss and near-edge core excitation spectroscopy to be performed.
27 citations
TL;DR: In this article, the authors quantitatively evaluated the contrast in phase contrast images of thin vermiculite crystals recorded by TEM and aberration-corrected bright-field STEM.
17 citations
TL;DR: In this paper, the nano-scale chemical distribution and microstructure of a nitride-based wear and oxidation resistant coating prepared by unbalanced magnetron sputtering was investigated, which consisted of multilayers of CrAlYN/CrN with a partially oxidised CrAlY(O)N/Cr(O),N oxy-nitride surface layer.
16 citations
TL;DR: In this article, columnar CoCrPt grains with their c-axis pointing perpendicular to the particle surface were formed, creating a unique hedgehog-like cap structure, which substantially modifies the magnetic properties.
Abstract: Granular CoCrPt–SiO2 films with perpendicular magnetic anisotropy were deposited onto arrays of SiO2 nanoparticles with diameters down to 10 nm. Columnar CoCrPt grains with their c-axis pointing perpendicular to the particle surface were formed, creating a unique hedgehog-like cap structure. This peculiar structure induced by the curvature of the particles substantially modifies the magnetic properties. Underneath the CoCrPt pillars a continuous Co-rich layer was observed, which gives rise to enhanced intergranular exchange coupling resulting in single domain states. The temperature dependence of the coercivity and the angular dependence of the switching field were extracted and correlated with the microstructure.
5 citations
TL;DR: In this article, a complex layered oxide has been synthesized as bulk material starting from the theoretical n ǫ = 2 R-P formula Sr 3 (Mg x Mo 1 − x ) 2 O 7 − δ (x  ≥ 0.25).
3 citations
01 Jul 2010
TL;DR: In this paper, the authors applied spectroscopic imaging and advanced STEM analysis to study the interfaces between the substrate and the metal ion pre-etching of the substrate surface, which has been shown to significantly enhance the adhesion between the coating and substrate.
Abstract: Nitride based protective coatings produced by physical vapour deposition offer a promising means to extend the oxidation and wear performance of γ-TiAl. Metal ion pre-etching of the substrate surface has been shown to significantly enhance the adhesion between the coating and substrate. In this study we have applied spectroscopic imaging and advanced STEM analysis to study such interfaces. For a conventional Cr cathodic arc discharge Cr ion implantation of ~6nm into the substrate was observed. For an etch using high power impulse magnetron sputtering the metal ion implantation depth was reduced to ~2-3nm. In both cases a corresponding depletion zone of Ti and Al was observed. In addition, nitrogen diffusion into the substrate during coating deposition was also revealed to a similar depth respectively.
1 citations
01 Jul 2010
TL;DR: In this article, high-angle-annular-dark-field (HAADF) and bright-field lattice images of graphene acquired in an aberration-corrected scanning transmission electron microscope (STEM), in conjunction with electron energy-loss spectroscopy (EELS), show vacancy-and ad-atom-related point defects, as well as the presence of hydrogen.
Abstract: Graphene surfaces are scrutinised for topographic peculiarities, which occur naturally or have been introduced. High-angle-annular-dark-field (HAADF) and bright-field lattice images of graphene acquired in an aberration-corrected scanning transmission electron microscope (STEM), in conjunction with electron energy-loss spectroscopy (EELS), show vacancy- and ad-atom-related point defects, as well as the presence of hydrogen. In boron implanted graphene, the edges of graphene sheets appear to be capture centres for boron atoms. Furthermore, rippling effects in the graphene sheets can be revealed by fast Fourier transform (FFT) procedures; these help visualise changes in the bond length projection arising from inclinations of the sheet.