1,721,015 research outputs found
Investigating the development of spurious magnetism in single crystalline BaTi0.95Fe0.05O3−δ with high δ by local structural probes
No full textBaTi0.95Fe0.05O3−δ has been suggested to be an intrinsic dilute magnetic oxide with a clear dependence of magnetism on oxygen vacancy concentration. However, it has also been shown that the dopant Fe ions distribute themselves rather inhomogeneously within the lattice, though without disrupting the crystal phase of the parent BaTiO3. With the help of x-ray absorption spectroscopy (XAS), here we find that the incorporation of a larger amount of anion vacancy pushes this inhomogeneity to the extreme, leading to the precipitation of Fe metal clusters. It is also observed that the residual solid, without the Fe-metal cluster, undergoes massive structural and compositional reorganization
XAFS study on Sr2FeMoxW1-xO6 double perovskite series
No full textSr2FeMoO6 oxide exhibit a half-metallic ferromagnetic (HMFM) ground state and has peculiar magnetic and magnetotransport properties that are very interesting both for applications and for fundamental research in the field of heavily correlated electron systems. In contrast to Sr2FeMoO6, Sr2FeWO6 is an insulator with an antiferromagnetic (AFM) ground state. Doping Sr2FeMoO6 with W, obtaining Sr2FeMoxW1−xO6 compounds, a composition driven metal to insulator transition (MIT) occurs at xc∼ 0.25. The nature of such transition is still a matter of debate and different possible scenarios have been proposed. This paper reports a detailed X-ray absorption spectroscopy (XAS) study on the Sr2FeMoxW1−xO6 series as a function of composition (0≤x≤1). The results demonstrate the presence of an abrupt change of the local atomic structure at xc that represents the structural counterpart of the electronic changes associated with the metal insulator transition
Sugata Ray, Climate Change and the Art of Devotion.,Geoaesthetics in the Land of Krishna, 1550–1850, Seattle, University of Washington Press (Global South Asia Series), 2019.
No full textSchmid Charlotte. Sugata Ray, Climate Change and the Art of Devotion.,Geoaesthetics in the Land of Krishna, 1550–1850, Seattle, University of Washington Press (Global South Asia Series), 2019.. In: Arts asiatiques, tome 75, 2020. pp. 182-184
Nature of ‘‘Disorder’’ in the Ordered Double Perovskite Sr2FeMoO6
No full textThe degree of B/B' alternate cation order is known to heavily influence the magnetic properties of
A2BB'O6 double perovskites although the nature of such disorder has never been critically studied. Our
detailed x-ray absorption fine structure studies in conjunction with synchrotron radiation x-ray diffraction
experiments on polycrystalline Sr2FeMoO6 samples with various degrees of disorder reveal that a very
high degree of short range order is preserved even in samples with highly reduced long range chemical
order. Based on these experimental results and with the help of detailed structural simulations, we are able
to model the nature of the disorder in this important class of materials and discuss the consequent
implications on its physical properties
LaSrVMoO<sub>6</sub>A case study for A-site covalency-driven local cationic order in double perovskites
No full textAn unusual atomic scale chemical fluctuation in LaSrVMoO6, in terms of narrow patches of La,V and Sr,Mo-rich phases, has been probed in detail to understand the origin of such a chemical state. Exhaustive tuning of the equilibrium synthesis parameters showed that the extent of phase separation can never be melted down below a unit cell dimension making it impossible to achieve the conventional B-site ordered structure, which establishes that the observed “inhomogeneous” patchlike structure with minimum dimension of few angstroms is a reality in LaSrVMoO6. Therefore another type of local chemical order, hitherto unknown in double perovskites, gets introduced here. X-ray diffraction, electron microscopy elemental mapping, magnetic, and various spectroscopic studies have been carried out on samples, synthesized under different conditions. These experimental results in conjunction with ab initio electronic structure calculation revealed that it is the energy stability, gained by typical La-O covalency as in LaVO3, that leads to the preferential La,V and Sr,Mo ionic proximity, and the consequent patchy structure
Local structure of Sr2FeMoxW1-xO6 double perovskites studied by EXAFS
No full textSr2FeMoO6 double perovskits display low field MR at a relatively high temperature and unusual ferromagnetic properties. These compounds depicts metal to insulator transition increasing x above xc ~ 0.25. A comparative analysis of the near edge regions (XANES) suggests that iron is Fe3+ in the metallic range. Checking the end compounds, we found that the doped samples can be viewn as inhomogeneous distributions of the end compounds. This could help to distinguish between the two scenarios proposed to explain the metal to insulator transition. Moreover, the local atomic structure of Sr2FeMoxW1−xO6 as a function of composition (0 ≤ x ≤ 1) has been investigated by Extended x-ray absorption spectroscopy (EXAFS) a the Fe, Mo, Sr K-edges and W LIII-edge
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Nature of "Disorder'' in the Ordered Double Perovskite Sr2FeMoO6
No full textThe degree of B/B' alternate cation order is known to heavily influencethe magnetic properties of A(2)BB'O-6 double perovskites although thenature of such disorder has never been critically studied. Our detailedx-ray absorption fine structure studies in conjunction with synchrotronradiation x-ray diffraction experiments on polycrystalline Sr2FeMoO6samples with various degrees of disorder reveal that a very high degreeof short range order is preserved even in samples with highly reducedlong range chemical order. Based on these experimental results and withthe help of detailed structural simulations, we are able to model thenature of the disorder in this important class of materials and discussthe consequent implications on its physical properties
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