A. S. N. Murthy, C. N. R. Rao, B. D. N. Rao and P. Venkateswarlu, Trans. Faraday Soc., 1962, 58, 855 DOI: 10.1039/TF9625800855
Two isostructural, organically-templated, 2D coordination polymers, one containing NiII and another containing CoII and NiII ions with the general formulae, {[EDAH2][M1M2F2(SO4)2(H2O)2]} n , (EDA=ethylenediamine, M1 =M2 =NiII (1), and M1 =CoII, M2 =NiII (2)) have been synthesized and structurally characterized. 1 and 2 consist of a 1D chain bridged by F− ion, [M–F–M] n which is interconnected by SO4 2− tetrahedra forming a 2D [Ni2F2(SO4)2(H2O)2] n 2− or [CoNiF2(SO4)2(H2O)2] n 2− corrugated sheet which are templated by diprotonated ethylenediamine [EDAH2] cation. Temperature-dependent magnetic measurements reveal the presence of spin-canted antiferromagnetism in both 1 and 2. 1 behaves like a soft magnet with a small magnetic hysteresis with a coercive field (Hc ) of 0.46kOe and a remnant magnetization (MR ) of 0.09 μ B. 2, on the other hand exhibits relatively a hard magnet like behavior with large magnetic hysteresis with Hc =8.74kOe and MR =0.76 μ B. The difference in magnetic behaviors of 1 and 2 is attributed to the difference in single-ion magnetic anisotropy and spin magnitudes of NiII (S =1) and CoII (S =3/2) ions.
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An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and Isomerization of Substituted 5-Amino-1,2,3-triazoles1EUGENE LIEBER, TAI SIANG CHAO, and C. N. RAMACHANDRA RAOCite this: J. Org. Chem. 1957, 22, 6, 654–662Publication Date (Print):June 1, 1957Publication History Published online1 May 2002Published inissue 1 June 1957https://doi.org/10.1021/jo01357a018RIGHTS & PERMISSIONSArticle Views502Altmetric-Citations62LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts
Transition–metal oxides of perovskite structure exhibit compositionally controlledmetal–insulator (M–I) transitions wherein the temperature coefficient of resistivity changes sign at a resistivity value close to Mott's maximum metallic resistivity. These oxides also obey the Mott's criterion, nc1/3aH ≈ 0.25, arising from electron interactions. Cuprate superconductors, in spite of their anomalous properties in the metallic state, obey the above two criteria for metallicity. The cuprates also exhibit unusual insulator–superconductor and M–I transitions. Perovskite manganates which exhibit giant magnetoresistance, on the other hand, show high resistivities (ρ>ρmax) of Mott) at low temperatures, in the ‘metallic’ state, and the mechanism of the M–I transition in these materials is not clear. Jahn–Teller distortion and charge ordering compete with double exchange and the electronic properties are accordingly determined by the dominant interaction. While double exchange favours ferromagnetism and metallicity, charge–ordering and Jahn–Teller effects favour insulating behaviour. Charge ordering in the manganates is specially interesting being strongly affected by the size of the A–site cations.
No abstract is provided for this article.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Magnetic susceptibility data show La 2 CuO 4 to be antiferromagnetic. Oxides of the K 2 NiF 4 structure of the general formula (La 1−y Ln y ) 2−x Sr x (Ba x )CuO 4 show superconductivity in the 15-40K range, the T c becoming maximum at a specific value of x or of the a-parameter. Superconductivity in La 3−x Ba 3+x Cu 6 O 14 and La 4−x Ba 1+x Cu 5 O 13 systems has been investigated besides that in the Y-Ba-Cu-O system. Role of oxygen in the superconductivity of YBa 2 Cu 3 O 7−δ is discussed. The problem of rationalizing macro and microstructures of YBa 2 Cu 3 O 7−δ is indicated. Infrared spectra of the superconducting oxides and their marginal metallicity in the normal state are examined. Based on electron spectroscopic studies, it is shown that holes are likely to be on oxygen rather than on copper, giving rise to peroxide-like species; Copper is present in the 1+ state (besides the 2+ state).
