Following the theoretical predictions of ferromagnetism in Mn- and Co-doped ZnO, several workers reported ferromagnetism in thin films as well as in bulk samples of these materials. While some observe room-temperature ferromagnetism, others find magnetization at low temperatures. Some of the reports, however, cast considerable doubt on the magnetism of Mn- and Co-doped ZnO. In order to conclusively establish the properties of Mn- and Co-doped ZnO, samples with 6 percent and 2 percent dopant concentrations, have been prepared by the low-temperature decomposition of acetate solid solutions. The samples have been characterized by x-ray diffraction, EDAX and spectroscopic methods to ensure that the dopants are substitutional. All the Mn- and Co-doped ZnO samples (prepared at 400 deg C and 500 deg C) fail to show ferromagnetism. Instead, their magnetic properties are best described by a Curie-Weiss type behavior. It appears unlikely that these materials would be useful for spintronics, unless additional carriers are introduced by some means.
Magnetic and electric properties of a single crystal of La0.7Ca0.3CoO3 have been experimentally studied. The system attains a ferromagnetic spontaneous moment below 170 K and exhibits a re-entrant spin-glass phase below 100 K. In the ordered and the re-entrant phases, the low field magnetic properties are strongly direction dependent, showing considerably higher magnetization values perpendicular than parallel to the c-axis. Magnetic relaxation experiments show that both the ferromagnetic and the re-entrant spin-glass phases are non-equilibrium states, where the system exhibits magnetic aging characteristic of spin-glasses and disordered and frustrated ferromagnets. *for correspondence: cnrrao@jncasr.ac.in
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.
$MoSe_2$ and $WSe_2$ nanotubes are obtained by the reduction of the corresponding triselenides in hydrogen or by the decomposition of the ammonium selenometallates in a hydrogen atmosphere.
We discussed several interesting and useful properties of solids in the previous chapter. Tailor-making materials of desired properties is an integral part of modern solid state chemistry and an account of the subject would be incomplete without reference to it. To do justice to any one class of materials or to any one type of application, we would have to deal extensively with materials design, devices and other technological details. Since this would be beyond the scope of this monograph, we shall briefly present a few of the selected materials applications.
Characterization is an essential part of all investigations in solid state chemistry and materials science. The various aspects of characterization are: (i) chemical composition and compositional homogeneity of the specimen, (ii) impurities that may affect the properties, (iii) structure, revealing the crystallinity or otherwise of the specimen, crystal system, unit cell and where possible (or necessary) atomic coordinates, bonding and ultrastructure and (iv) the nature and concentration of imperfections (defects) influencing properties. While it may not be possible to achieve complete characterization of a given solid by a single investigator or at any given time, yet without a minimum level of characterization no investigation can be initiated or completed. The scope of ‘characterization’ is so vast that nearly all aspects of solid state chemistry can be included under its domain. According to the US Materials Advisory Board Committee, ‘characterization describes those features of the composition and structure (including defects) of a material that are significant for a particular preparation, study of properties or use, and suffice for reproduction of the material’. The subject of characterization has been reviewed sufficiently in the literature (Cheetham & Day, 1987; Meinke, 1973; Newnham & Roy, 1973; Honig & Rao, 1981; West, 1985) and we shall therefore recount the main essentials and highlight some of the recent developments. The advances made in the last few years in characterization techniques, especially in structure elucidation, have been truly remarkable and have opened new vistas in solid state chemistry.
Y-junction carbon nanotubes can be produced in relatively large quantities by the vapor phase pyrolysis of a mixture of cobaltocene or ferrocene with thiophene in a hydrogen atmosphere. Pyrolysis of Ni- and Fe-phthalocyanines or Fe(CO)5 with thiophene also yields Y-junction nanotubes. Good yields of Y-junction nanotubes were obtained by pyrolyzing thiophene over an Ni(Fe)/SiO2 catalyst as well. Many of the nanotubes show multiple Y-junctions. Of the various methods employed by us, the pyrolysis of thiophene with metallocenes or over a Ni(Fe)/SiO2 catalyst yields the best results and the latter is a less expensive route. The availability of large quantities of Y-junctions by the procedures employed here should render them useful for exploitation in nanoelectronics.
A novel iron phosphate, [(C4N3H16)(C4N3H15)]5+-[Fe5F4(H2PO4)(HPO4)3(PO4)3]5–·H2O, consisting of a Fe–O/F–Fe network crosslinked by PO4 groups is shown to possess unusually large elliptical voids of 24 T atoms (T = Fe, P) and to exhibit a gradual low- to high-spin transformation.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAN ELECTRON DIFFRACTION INVESTIGATION OF THE MOLECULAR STRUCTURE OF METHYL AZIDE1R. L. Livingston and C. N. Ramachandra RaoCite this: J. Phys. Chem. 1960, 64, 6, 756–759Publication Date (Print):June 1, 1960Publication History Published online1 May 2002Published inissue 1 June 1960https://pubs.acs.org/doi/10.1021/j100835a012https://doi.org/10.1021/j100835a012research-articleACS PublicationsRequest reuse permissionsArticle Views54Altmetric-Citations35LEARN 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 InRedditEmail Other access options Get e-Alerts
Since micron size gold particles have several possible applications, we have explored ways of producing uniform gold powders of these dimensions. It is found that by employing ethylene glycol or diethylene glycol as solvent as well as reducing agent, non-agglomerated spherical particles of gold can be prepared.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroscopic studies of self-association due to hydrogen bondingSurjit Singh and C. N. Ramachandra RaoCite this: J. Phys. Chem. 1967, 71, 4, 1074–1078Publication Date (Print):March 1, 1967Publication History Published online1 May 2002Published inissue 1 March 1967https://pubs.acs.org/doi/10.1021/j100863a044https://doi.org/10.1021/j100863a044research-articleACS PublicationsRequest reuse permissionsArticle Views213Altmetric-Citations86LEARN 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 InRedditEmail Other access options Get e-Alerts
