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Arc-discharge with carbon electrodes containing Ni and Y2O3 in the presence of Fe(CO)5 vapors have been investigated. It is found that unlike the cathode deposit, the web deposited in the chamber contains mainly metallic single-walled carbon nanotubes (SWNTs) as evidenced from Raman and optical absorption spectroscopy. The percentage of metallic SWNTs increases with the concentration of Fe(CO)5. Under optimal conditions, the web contains over 90% of metallic SWNTs. This method enables the synthesis of nearly pure metallic SWNTs on a large scale.
Bimetallic clusters of Ni-Pd, Cu-Ni, Cu-Au and Au-Ni deposited on amorphized graphite have been investigated by a combined use of photoelectron spectroscopy and electron microscopy. Metal core-level binding energies (Pd 3d, Au 4f and Ni/Cu 2p) of the bimetallic clusters deposited on amorphized graphite have been measured for different coverages or mean cluster sizes. When the cluster is large, the core-level binding energy of the major metallic component in the bimetallic clusters (e.g. Cu in Cu3Au or Cu7Ni3) is close to that of the bulk metal while that of the minor component (e.g. Au in Cu3Au or Ni in Cu7Ni3) shows the effect of alloying. The effect of alloying is found in the core-level energies of both Ni and Pd in the large clusters ofNi3Pd2. With the decrease in cluster size or coverage, the core-level binding energies of both the metals increase, just as in the case of monometallic clusters. The present results show the occurrence of parallel shifts in the core-level binding energy of metals due to alloying and cluster size effects, both the effects manifesting themselves in the small clusters. It is noteworthy that the core-level binding energy shifts in bimetallic clusters are distinctly different from those in bimetallic overlayers. Although alloy formation does not occur in the Au-Ni system in the bulk, the Au3Ni and Ni3Au clusters show variations in binding energies similar to the alloy clusters. It appears that alloying in the Au-Ni system may indeed occur in the nanometric regime of clusters.
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Systematics in the ionization energies corresponding to the different π orbitals of para, meta and ortho-disubstituted benzenes obtained from PES have been investigated. The data have been discussed in terms of correlations with substituents constants and such correlations are shown to provide the basis to differentiate steric from electronic effects in the case of ortho derivatives. Ionization energies from PES corresponding to the lone pair orbitals of substituents in related series of p-disubstituted benzenes are shown to vary systematically with the substituent constants.
Charge-ordered phases of rare earth manganates are novel manifestations arising from interactions between the charge carriers and phonons, giving rise to the localization of carriers at specific sites in the lattice below a certain temperature. Accompanying this phenomenon, the Mn3+(eg ) orbitals and the associated lattice distortions also exhibit long range ordering (orbital ordering). What makes the manganates even more interesting is the occurrence of complex spin ordering related to anisotropic magnetic interactions. In this article, we discuss the emerging scenario of charge-ordered rare earth manganates in the light of specific case studies and highlight some of the new experimental findings related to spin, orbital and charge ordering. We also examine features such as the charge stripes and phase separation found experimentally in these materials, and discuss the factors that affect charge-ordering such as the size of A-site cations and magnetic and electric fields, as well as isotopic and chemical substitutions.
Chemical methods of synthesis of materials play a crucial role in designing and discovering new materials and also in providing better and less cumbersome methods for preparing known materials. In this article, we shall discuss the chemical synthesis of inorganic solids, in particular oxidic materials. We shall first briefly examine the different classes of chemical reactions generally employed for synthesis and then discuss the various methods used along with several case studies and examples. In addition to the traditional ceramic method, the topics discussed include the combustion method (self-propagating high-temperature synthesis), the precursor method, topochemical routes, intercalation compounds, the ion-exchange method, the sol-gel process, the alkali-flux method, electrochemical methods, the pyrosol process and high pressure methods. The last topic includes hydrothermal synthesis of zeolitic materials. Intergrowth structures and superconducting cuprates are discussed in separate sections. It is hoped that the article will provide a useful survey of chemical methods of synthesis of inorganic materials and will serve as a ready reference to practitioners of the subject.
Thin films of GaN, InGaN, AlGaN and AlN on Si(100) as well as on Al2O3(0001) single crystalline substrates have been deposited at 1123, 1023, 1173 and 1173K, respectively, by employing the simple inexpensive technique of nebulized spray pyrolysis. GaN films deposited on Si are polycrystalline where as the films deposited on Al2O3 are epitaxial. GaN epitaxial films show cathodoluminescence characteristics. Photoluminescence studies show that all the films are of high quality.
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal and molecular structures of alkali- and alkaline-earth-metal complexes of N,N-dimethylformamideC. Pulla Rao, A. Muralikrishna Rao, and C. N. R. RaoCite this: Inorg. Chem. 1984, 23, 14, 2080–2085Publication Date (Print):July 1, 1984Publication History Published online1 May 2002Published inissue 1 July 1984https://pubs.acs.org/doi/10.1021/ic00182a020https://doi.org/10.1021/ic00182a020research-articleACS PublicationsRequest reuse permissionsArticle Views329Altmetric-Citations38LEARN 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 optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts
The ultraviolet photoelectron spectrum of the H2S dimer shows four features with vertical ionization energies of 9.75, 10.95, 12.37 and 13.69 eV; the adiabatic ionization energies of the first two ionic states are 9.56 and 10.75 eV. Molecular-orbital calculations reveal that the first two features are due to the sulphur lone pairs while the others to the πSH2 orbitals. The ground ionic state (1 2A″) of the dimer is bound by 0.96 eV and the structure undergoes significant distortion on ionization. The first excited ionic state (1 2A′) is repulsive.
C. N. R. Rao, J. Mater. Chem., 1999, 9, 1 DOI: 10.1039/A804467H
The occurrence of surface ferromagnetism in inorganic nanoparticles as a universal property not only explains many of the unusual magnetic features of oxidic thin films, but also suggests its possible use in creating new materials, as exemplified by multiferroic BaTiO3 nanoparticles. While the use of Mn-doped ZnO and such materials in spintronics appears doubtful, it is possible to have materials exhibiting the coexistence of (bulk) superconductivity and (surface) ferromagnetism.
