Sailesh Chittipeddi

Bio: Sailesh Chittipeddi is an academic researcher from Ohio State University. The author has contributed to research in topics: Magnetic susceptibility & Magnetization. The author has an hindex of 8, co-authored 14 publications receiving 788 citations.

Ferromagnetic behavior of [Fe(C5Me5)2]+.bul. [TCNE]-.bul.. Structural and magnetic characterization of decamethylferrocenium tetracyanoethenide, [Fe(C5Me5)2]+.bul. [TCNE]-.bul..cntdot.MeCN and decamethylferrocenium pentacyanopropenide, [Fe(C5Me5)2]+.bul. [C3(CN)5]-

Abstract: Les deux composes cristallisent dans le systeme monoclinique, groupe C2/C. Comportement magnetique

Ferromagnetism in molecular decamethylferrocenium tetracyanoethenide (DMeFc TCNE)

Abstract: The temperature and magnetic field dependence of the magnetization and susceptibility of single-crystal decamethylferrocenium tetracyanoethenide (DMeFc TCNE) demonstrate that this material is the first molecular compound with a ferromagnetic ground state. A spontaneous magnetization is observed for Tl4.8 K. The results are consistent with a crossover from a dominance of one-dimensional ferromagnetic exchange interaction to a 3D mean-field-like interaction at \ensuremath{\sim}16 K. The critical exponents are in accord with mean-field behavior. A generalized Hubbard model is proposed to account for the unusual ferromagnetic exchange interactions in this system.

Resistive and magnetic studies of Nd 1 Ba 2 Cu 3 O 7 − δ and Pr 1 Ba 2 Cu 3 O 7 − δ

Abstract: We report resistivity, structural, and magnetic susceptibility [${\ensuremath{\chi}}^{\mathrm{spin}(\mathrm{T})]}$ measurements for the compounds ${\mathrm{Pr}}_{1}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ and ${\mathrm{Nd}}_{1}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$. The Nd compound is superconducting with an onset transition temperature of 90 K, while the Pr compound is semiconducting above 4 K. The lattice parameters for these two materials have been determined using x-ray diffraction techniques, and both appear to be tetragonal, although the ${\mathrm{Nd}}_{1}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ compound may exhibit some orthorhombic splitting. The high-temperature effective moments in the two systems are within a few percent of the free-ion moments. In each case the presence of significant curvature in the inverse susceptibility versus T behavior on the scale of 100 K suggests the presence of crystalline electric field splittings on the same energy scale. For the Pr compound this is further confirmed by a finite value for ${\ensuremath{\chi}}^{\mathrm{spin}}$(0) and a residual large constant term at high temperatures. The possible origin of semiconducting behavior as compared with superconducting behavior in the Nd and other rare-earth compounds is discussed in terms of differences in charge-carrier density and possible role of valence fluctuations among Pr rare-earth ions.

Experimental study of La1Ba2Cu3Ox.

Abstract: We have prepared samples in the La/sub 1/Ba/sub 2/Cu/sub 3/O/sub x/ series with superconducting transition temperatures T/sub c/ ranging from 23 to 72 K (onset temperatures from 43 to 88 K). Results from scanning-electron-microscopy characterization, x-ray diffraction analysis, thermogravimetric analysis, the temperature dependence of the resistivity, and temperature dependence of the magnetic susceptibility are presented. The samples with T/sub c/ greater than 50 K are orthorhombic while samples with T/sub c/ less than 50 K show tetragonal structure. The transition temperature is found to depend on the oxygen content x with an apparent peak near x = 7. Our sample with the highest T/sub c/ (72 K) had x = 6.75. As x decreases, so does T/sub c/, reaching 44 K when x = 6.47. For oxygen content greater than 7, T/sub c/ decreases rapidly to a value of 23 K when x = 7.27. The room-temperature resistivity increases systematically from 0.8 to 7.9 m..cap omega.. cm as T/sub c/ decreases from 72 to 27 K. The increase is resistivity in the normal state and the decrease in the resistivity ratio (rho/sub 300 K//rho/sub residual/ are interpreted in terms of disorder in the microscopic structure which suppresses T/sub c/. Themore » magnetic susceptibility of these samples separates into a Pauli susceptibility chi/sub 0/ and a Curie-Weiss susceptibility C/(T-FTHETA), after the core contribution is subtracted. A systematic increase in chi/sub 0/ and a decrease in the Curie constant C has been observed as T/sub c/ varies from 23 to 72 K.« less

Chemical Redox Agents for Organometallic Chemistry

Abstract: 1. Advantages of Chemical Redox Agents 878 2. Disadvantages of Chemical Redox Agents 879 C. Potentials in Nonaqueous Solvents 879 D. Reversible vs Irreversible ET Reagents 879 E. Categorization of Reagent Strength 881 II. Oxidants 881 A. Inorganic 881 1. Metal and Metal Complex Oxidants 881 2. Main Group Oxidants 887 B. Organic 891 1. Radical Cations 891 2. Carbocations 893 3. Cyanocarbons and Related Electron-Rich Compounds 894

Toward molecular magnets: The metal-radical approach

Abstract: Molecular materials are characterized by being made up by discrete molecules. This structural property gives in principle many possibilities, to modulate the bulk electrical, magnetic, and optical properties of the material by choosing appropriately the constituent molecules. At the same time, however, it is a challenge to develop synthetic strategies that allow the control of the spatial distribution of the molecules in the lattice. In fact, the bulk properties are always determined by cooperative interactions between the constituent molecules, which consequently must be assembled in the lattice in such a way as to maximize the bulk response. In this Account we provide a concise resume of magnetic phenomena, report briefly on the different strategies that have been developed up to the moment for designing molecular magnetic materials, and then summarize our own approach and the main results that have been obtained in this area.

Chemistry and physics of supramolecular magnetic materials.

Abstract: The building of multidimensional magnetic materials obtained with the molecular precursor [Cu(opba)]2- is described. The reaction with other paramagnetic species (3d or 4f metal ions, organic radicals) yielded one-dimensional, two-dimensional, and interlocked networks. The magnetic properties of these systems are reviewed using polarized neutron diffraction and magnetic measurements. It is shown that the spin density maps give a precise description of the ground state of such molecular magnetic species. Moreover, different long-range magnetic orderings (antiferro-, ferri-, and ferromagnetic) have been obtained.