@conference { ISI:000227460600024, title = {High magnetic aspects of nanosized NiZn ferrite powders synthesized by an autocombustion method}, booktitle = {9th International Conference on Ferrites (ICF-9)}, year = {2005}, note = {9th International Conference on Ferrites (ICF-9), San Francisco, CA, AUG 22-27, 2004}, month = {AUG}, pages = {149-154}, publisher = {Amer Ceramic Soc, 735 Ceramic Place, Westerville, OH 43081-8720 USA}, organization = {Amer Ceramic Soc, 735 Ceramic Place, Westerville, OH 43081-8720 USA}, address = {San Francisco, CA}, abstract = {

Nanocrystalline NiZn ferrite, Ni0.5Zn0.5Fe2O4, having particle size in the range 6-10 mn, has been synthesized by an auto-combustion method. The nanosized ferrite powder formed at a low temperature is annealed at different temperatures in the range 473-1273 K and characterized by X-ray diffraction, vibrating sample magnetometry, Mossbauer spectroscopy, transmission electron microscopy and scanning electron microscopy. Magnetic transition temperature broadening up to 773 K is observed for the nanosized sample, compared to the T-c = 563 K for the bulk material. Critical particle diameter (D-c) is found to be similar to 40 nm at which maximum coercivity is obtained for the powder sample annealed at 973 K. Similarly, high room temperature magnetization, comparable to that of the bulk material, is obtained for the powders annealed at 1073 K, with a maximum particle size of similar to 50 nm. Very little grain growth is observed for the powders annealed above 1073 K. The results show that, optimum magnetic properties can be achieved for fine particle NiZn ferrite powders synthesized by a low-temperature auto-combustion method and processed at relatively lower temperatures.

}, isbn = {1-57498-218-4}, author = {Deka, Sasanka and Date, Sadgopal K. and Joy, Pattayil Alias}, editor = {Soohoo, R. F.} } @conference { ISI:000227460600023, title = {Magnetic properties of nanosized ferrite powders synthesized by microwave-hydrothermal method}, booktitle = {Ninth International Conference on Ferrites (ICF-9)}, year = {2005}, note = {9th International Conference on Ferrites (ICF-9), San Francisco, CA, AUG 22-27, 2004}, month = {AUG}, pages = {143-148}, publisher = {Amer Ceramic Soc, 735 Ceramic Place, Westerville, OH 43081-8720 USA}, organization = {Amer Ceramic Soc, 735 Ceramic Place, Westerville, OH 43081-8720 USA}, address = {San Francisco, CA}, abstract = {

Nanosized powders of Fe3O4 and MgFe2O4 are synthesized by microwave-hydrothermal (MH) method. The ferrite powders thus obtained are characterized by powder X-ray diffraction, Mossbauer spectroscopy, scanning and transmission electron microscopies, vibrating sample magnetometer and AC magnetic susceptibility studies. Stoichiometric, nanosized (similar to 34 nm) Fe3O4 particles, having cubic symmetry with a(0) approximate to 8.39 angstrom, are obtained when molar ratio of Fe/NaOH used for the synthesis is 0.133. On the other hand, non-stoichiometric Fe3O4 is obtained when Fe/NaOH molar ratio is increased to 0.4. Though the powder XRD patterns of both stoichiometric and non-stoichiometric Fe3O4 are identical, Mossbauer spectroscopic studies showed different features in terms of asymmetry, intensity, isomer shift, etc. Saturation magnetization, M-s = 70 emu/g and coercivity, H-c = 178 Oe, at room temperature, are obtained for stoichiometric Fe3O4 powders. In the case of MgFe2O4, spherical, nanosized (similar to 3 nm) powders with cubic symmetry (a(0) approximate to 8.30 angstrom) and having very narrow size distribution are obtained under the MH conditions. The temperature and field dependent magnetic measurements on MgFe2O4 powders confirmed the existence of superparamagnetic state in this material with a superparamagnetic blocking temperature of 38 K below which typical magnetic hysteresis behaviour is observed.

}, isbn = {1-57498-218-4}, author = {Khollam, Y. B. and Dhage, S. R. and Verma, S. and Potdar, H. S. and Deshpande, S. B. and Joy, Pattayil Alias and Date, Sadgopal K.}, editor = {Soohoo, R. F.} } @conference { ISI:000227460600141, title = {Synthesis and magnetic properties of polycrystalline Co-doped ZnO}, booktitle = {9th International Conference on Ferrites (ICF-9)}, year = {2005}, note = {9th International Conference on Ferrites (ICF-9), San Francisco, CA, AUG 22-27, 2004}, month = {AUG}, pages = {913-918}, publisher = {Amer Ceram Soc; Japan Soc Powder \& Powder Met; Int Magnet Assoc; Amer Phys Soc}, organization = {Amer Ceram Soc; Japan Soc Powder \& Powder Met; Int Magnet Assoc; Amer Phys Soc}, address = {San Francisco, CA}, abstract = {

Nanocrystalline Zn1-xCoxO powders have been synthesized by a glycine-nitrate (GNP) and modified GNP methods. Ferromagnetism at room temperature and above is observed for the powder samples synthesized by GNP method. The saturation magnetization value at 300 K is obtained as 0.08 and 0.28 emu/g (at 1 T), respectively, for x = 0.05 and 0.1. Ferromagnetic transition occurs at 740 K and 770 K for the respective samples, which is much larger than that the reported in the literature for thin film samples. On the other hand, no ferromagnetism was observed, down to 10 K, for the compounds synthesized by the modified GNP method.

}, isbn = {1-57498-218-4}, author = {Deka, Sasanka and Date, Sadgopal K. and Joy, Pattayil Alias}, editor = {Soohoo, R. F.} }