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Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization

100%

Ozkaya T., Baykal A., Koseoğlu Y., Kavas H.

Open Chemistry

2009

vol. 7

issue 3

410-414

Without any surfactant, antiferromagnetic Co3O4 nanoparticles were synthesized successfully for the first time by means of an oxidation-reduction method with cobalt sulfate as starting material, which was oxidized to cobalt salt by NaNO3 after alkalinizing with NaOH. Morphological, structural, spectroscopic and magnetic characterization of the product were done by SEM, TEM, XRD, and VSM, respectively. The average crystallite size (on the base of line profile fitting method), D and σ, is estimated as 30 ± 6 nm. Some anomalous magnetic properties and their enhanced effect have been observed in Co3O4 antiferromagnetic nanocrystallites, including a bias field, coercivity, permanent magnetic moments and an open loop. These phenomena are attributed to the unidirectional anisotropy which is caused by the exchange coupling between AFM and FM layers, the existence of the spin glass like surface spins of Co3O4 nanoparticles due to size effects and surface-area effect. [...]

Synthesis, characterization and magnetic investigation of (NH4)0.5Mn1.25(H2O)2[BP2O8]·0.5H2O

100%

Birsöz B., Baykal A., Toprak M., Köseoglu Y.

Open Chemistry

2007

vol. 5

issue 2

536-545

A new borophosphate compound with the composition (NH4)χ Mn((3−χ)/2)(H2O)2 [BP2O8]·(1−x)H2O was prepared under mild hydrothermal conditions and characterized by X-ray powder diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) methods. The title compound was synthesized from MnCl2·2H2O, H3BO3, and (NH4)2HPO4 with variable molar ratios by heating at 180 °C for 7 days in an autoclave. The X-ray diffraction data of the water insoluble polycrystalline powder was indexed using the TREOR program in hexagonal system with the unit cell parameters of a = 9.5104, c = 15.7108 Å, Z = 6 and the space group P65 (No.176). (NH4)χ Mn((3−χ)/2)(H2O)2 [BP2O8]·(1−x)H2O is isostructural with (NH4)χ M ((3−χ)2)/II (H2O)2 [BP2O8]·(1−x)H2O (MII = Co, Cd, Mg; x = 0.5–1). Its unit cell parameters and hkl values were in good agreement with the other isostructural compounds. This is the first report presenting both the synthetic details and the indexed X-ray powder diffraction pattern of this compound along with the characterization by FTIR, thermal gravimetric analysis, scanning electron microscopy and EPR. [...]

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2 Open Chemistry

1 2009

1 2007

2 Baykal A.

1 Birsöz B.

1 Kavas H.

1 Koseoğlu Y.

1 Köseoglu Y.

1 Ozkaya T.

1 Toprak M.

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Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization

Synthesis, characterization and magnetic investigation of (NH4)0.5Mn1.25(H2O)2[BP2O8]·0.5H2O