@article { ISI:000302143900017, title = {Magnetic and magnetoelastic properties of Zn-doped cobalt-ferrites-CoFe2-xZnxO4 (x=0, 0.1, 0.2, and 0.3)}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {324}, number = {14}, year = {2012}, month = {JUL}, pages = {2286-2291}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Cobalt-ferrite (CoFe2O4) based materials are suitable candidates for magnetomechanical sensor applications owing to a strong sensitivity of their magnetostriction to an applied magnetic field. Zn-doped cobalt-ferrites, with nominal compositions CoFe2-xZnxO4 (x=0-0.3), were synthesized by auto-combustion technique using Co-, Fe-, and Zn-nitrate as precursors. X-ray spectra analysis and Transmission electron microscopy studies revealed that the as-prepared powders were comprised of nano-crystalline (similar to 25-30 nm) cubic-spinel phase with irregularly-shaped grains morphology along with minor impurity phases. Calcination (800 degrees C for 3 h) of the precursor followed by sintering (1300 degrees C for 12 h) resulted in a single phase cubic-spinel structure with average grain size similar to 2-4 mu m, as revealed from scanning electron micrographs. The magnitude of coercive field decreases from similar to 540 Oe for x=0 to 105 Oe for x=0.30. Saturation magnetization initially increases and peaks to similar to 87 emu/g for x=0.2 and then decreases. The peak value of magnetostriction monotonically decreases with increasing Zn content in the range 0.0-0.3; however the piezomagnetic coefficient (d lambda/dH) reaches a maximum value of 105 x 10(-9) Oe-1 for x=0.1. The observed variation in piezomagnetic coefficient in the Zn substituted cobalt ferrite is related to the reduced anisotropy of the system. The Zn-doped cobalt-ferrite (x=0.1) having high strain derivative could be a potential material for stress sensor application. (C) 2012 Elsevier B.V. All rights reserved.

}, keywords = {Cobalt-ferrite, Magnetic-properties, Magnetostriction}, issn = {0304-8853}, doi = {10.1016/j.jmmm.2012.02.116}, author = {Somaiah, Nalla and Jayaraman, Tanjore V. and Joy, Pattayil Alias and Das, Dibakar} } @article {43882, title = {Activity tuning of cobalt ferrite nanoparticles anchored on N-doped reduced graphene oxide as a potential oxygen reduction electrocatalyst by Zn substitution in the spinel matrix}, journal = {Chemistry Select}, volume = {2}, year = {2017}, month = {SEP}, pages = {7845-7853}, type = {Article}, abstract = {

Development of highly efficient and durable ORR catalysts by using non-platinum group metals (such as Co, Fe, Mn, and Zn) is a challenging task in the forward path towards the realization of low-cost energy devices in the commercial stream. The present work deals with an effective strategy wherein an efficient Pt-free electrocatalyst for oxygen reduction reaction (ORR) is prepared by stoichiometrically substituting some fraction of Fe with Zn in cobalt ferrite and anchoring these spinel nanoparticles on nitrogen doped reduced graphene oxide (N-rGO). Zn substitution is found to be significantly altering the ratio of Fe2+/Fe3+ in the cobalt ferrite nanocrystal system with a concomitant promotional influence on its electrocatalytic activity towards ORR. The nanoparticle composition with a Co, Fe and Zn molar ratio of 1.0:1.7:0.3, represented by the formula CoFe1.7Zn0.3O4(CFZn(0.3)), supported over N-rGO has shown 10 mV and 20 mV positive shift in the onset and half-wave potentials, respectively, for ORR in 0.1 M KOH in comparison to the nanoparticles of CoFe2O4 supported over N-rGO (CF/N-rGO). The optimum Zn substitution is found to be narrowing down the difference with the state-of-the-art Pt/C for ORR by 100 and 110 mV in terms of the onset and half-wave potentials, respectively. Most significantly, the homemade catalyst is found to be clearly outperforming the Pt catalyst in terms of the limiting current density and electrochemical durability.

}, keywords = {Carbon Nano-fiber, Cathod Catalyst, CoFe2O4, Evolution, Magnetic-properties, Membrane fuel- Cell, Metal-Air Batteries, N-doped graphene, Nanocrystalline, nanocrystals, oxygen reduction reaction, performance, Platinium, solvothermal synthesis, Zn substituted cobalt ferrite}, issn = {2365-6549}, doi = {10.1002/slct.201701684}, author = {Kashyap, Varchaswal and Singh, Santosh K. and Kurungot, Sreekumar} } @article {43906, title = {Direct C-N bond formation in an in situ ligand transformation reaction and formation of polymeric 1D cadmium(II) complexes with end-to-end bridging thiocyanate or selenocyanate ions: Synthesis, structures and theoretical studies}, journal = {Polyhedron}, volume = {133}, year = {2017}, month = {SEP}, pages = {8-15}, type = {Article}, abstract = {

Two new one-dimensional polymeric thiocyanato and selenocyanato bridged cadmium(II) complexes [Cd(dpip)(mu(1,3)-SCN)(2)](n) and [Cd(dpip)(mu(1,3)-SeCN)(2)](n), where dpip = 3,5-dimethy1-14(3-phenylimidazolidin-ly1)-methyl)-1H-pyrazole have been synthesized and characterized by elemental analysis, IR, 1H NMR and single crystal X-ray diffraction studies. The bidentate N-2-coordinated ligand dpip is formed from N-4-coor-dinated tetradentate ligand N,N-bis(3,5-dimethy1-1H-pyrazol-1-yOmethyl-N-2-phenylethane-1,2-diamine (bdpab) due to unusual transformation, removing one pyrazole group and formation of saturated imidazole ring during in situ complexation reaction. The 1D structures of the two complexes have been confirmed by single crystal X-ray diffraction studies and both NCS- and NCSe- act as end -to -end (-1,3) bridging ligands. The coordination environment around the cadmium center in the complexes are CdN4S2 and CdN4Se2, respectively and each cadmium(II) center has distorted octahedral geometry. The distortion in the molecules are due to two unequal Cd-N (organic ligand dpip) bond lengths and small bite angel of the unsymmetrical organic ligand. The DFT calculations performed with cadmium(II) complexes [Cd (dpip)(mu(1,3)-SCN)(2)](n) and [Cd(dpip)(mu(1,3)-SeCN)(2)](n) corroborated the observed crystal structures and the structural parameter were found to be in good agreement in both calculated and X-ray geometries. (C) 2017 Elsevier Ltd. All rights reserved.

}, keywords = {1d Chain, Cd(Ii) Complexes, Cobalt(Ii), coordination polymers, Crystal-structure, Dft Pyrazole Based Ligand, Dinuclear, End-to-end Bridge, Infrared-spectra, Magnetic-properties, Metal, Ncs/Secn Ion, Nickel(Ii), Nitrogen Single Bond}, issn = {0277-5387}, doi = {10.1016/j.poly.2017.05.007}, author = {Sadhu, Mehul H. and Solanki, Ankita and Kundu, T. and Hingu, Vinayak and Ganguly, B. and Kumar, Sujit B.} }