1,720,977 research outputs found
X-ray Single-Crystal Structure and Magnetic Properties of Fe[CH3PO3)]·H2O: A Layered Weak Ferromagnet
No full textThe crystal and molecular structure of the layered weak-ferromagnet Fe[CH3PO3](H2O)-H-. has been solved by X-ray single-crystal diffraction techniques. Crystal data for Fe[CH3PO3](H2O)-H-. are the following: orthorhombic space group Pna2(1); a = 17.538(2), b = 4.814(l), c = 5.719(1) A. The structure is lamellar, and it consists of alternating organic and inorganic layers along the a direction of the unit cell. The inorganic layers are made of Fe(parallel to) ions octahedrally coordinated by five phosphonate oxygen atoms and one from oxygen of the water molecule. Each phosphonate group coordinates four metal ions, through chelation and bridging, making in this way a cross-linked Fe-O network. The resultant layers are then separated by bilayers of the methyl groups, with van der Waals contacts between them. The compound is air stable, and it dehydrates under inert atmosphere at temperatures above 120 degreesC. The oxidation state of the metal ion is +2, and the electronic configuration is d(6) high spin (S = 2), as determined from dc magnetic susceptibility measurements from 150 K to ambient temperature. Below 100 K, the magnetic moment of Fe[CH3PO3](H2O)-H-. rises rapidly to a maximum at T-max congruent to 24 K, and then it decreases again. The onset of peak at T = 25 K is associated with the 3D antiferromagnatic long-range ordering, T-N. The observed critical temperature, TN, is like all the other previously reported Fe(parallel to) phosphonates, and it appears to be nearly independent of the interlayer spacing in this family of hybrid organic-inorganic layered compounds. Below TN, the compound behaves as a "weak ferromagnet', and represents the third kind of magnetic materials with a spontaneous magnetization below a finite critical temperature, ferromagnets and ferrimagnets being the other two types
Spectroscopic characterization of (BEDT-TTF)<SUB>2</SUB>[Pt(S<SUB>2</SUB>C<SUB>4</SUB>O<SUB>2</SUB>)<SUB>2</SUB>] Charge Density Wave ground state
No full textStudy of the relationships between the structure of the doped spinels and their electrochemical performance in lithium batteries.
No full textDoping Li-Mn spinels with small amounts of metal ions (Zn, Ni, Co, Cr and Ti in this study) does remarkably affects its structural and electrochemical characteristics
COUPLING OF ELECTRONS TO LOW-FREQUENCY PHONONS IN CATION-RADICAL SALTS OF TTF STUDIED BY RESONANCE RAMAN-SCATTERING
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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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Method for synthesizing a cathodic Material Based on lithium ironphosphate, intrisically containing carbon
No full textL’invenzione consiste nella sintesi di litio ferro fosfato cristallino a granulometria micrometrica contenente carbone. La nuova via sintetica proposta si basa nella reazione ad alta temperatura, di un fosfonato alchilico di ferro (II) con carbonato di litio. Durante la reazione, il fosfonato si ossida a fosfato ed il gruppo alchilico si ossida in parte a carbonio elementare, che rimane intrappolato nella struttura del materiale. Il ruolo del carbone è di duplice importanza. Da una parte questo è necessario per impartire conducibilità elettronica al materiale, che è un forte isolante, e dall’altra, riesce a controllare la crescita cristallina limitandola a dimensioni micrometriche
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