Improvement in magnetic properties of La substituted BaFe12O19 particles prepared with an unusually low Fe/Ba molar ratio

Date

2011-07-01

Author

Sozeri, H.
KÜÇÜK, İLKER
Ozkan, H.

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

233
views

0
downloads

In this study, effect of lanthanum substitution on the phase composition, lattice parameters and magnetic properties of barium hexaferrite has been studied in samples synthesized in ammonium nitrate melt. Samples, prepared with different lanthanum amount and having various initial Fe/(Ba + La) ratios in between 12 and 2 {(Ba1-xLax).n Fe2O3, where 0 <= x <= 1 and 1 <= n <= 6)}, are sintered at temperatures from 800 to 1200 degrees C. The lattice parameters, both a and c, decreases with increasing La amount which results in a decrease of the unit cell volume. The scanning electron microscope micrographs show that the pure and La-substituted sample with x = 0.3, both calcinated at 1000 degrees C, have grain sizes smaller than 1 mu m. The coercivities of the La-substituted samples increase with increasing La amount and reaches to a maximum value of 5.73 kOe, when x = 0.3. Sintering at higher temperatures (above 1000 degrees C) decreases the coercivity, resembling a transition from single to multi-domain behavior of the particles, while saturation magnetization of the samples continues to increase due to the increasing grain size. Magnetization measurements of the samples prepared with different Fe/(Ba + La) molar ratios, n's, revealed that the specific saturation magnetization slightly increases with decreasing n, while coercivities fluctuates around 5.5 kOe. However, a sharp increase in the saturation magnetization has been observed in the sample having n 1 and washed in HCl. It was measured as 59.2 emu/g at 15 kOe, which is higher than that of the pure sample (57.5 emu/g). Thus, the magnetic parameters are optimized in the sample Ba0.7La0.3Fe12O19 so as to maximize both coercivity and specific saturation magnetization in the HCl-washed sample synthesized by starting with an unusually low Fe/(Ba + La) molar ratio of 2 (or n 1). Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.

Subject Keywords

HCl etching, Fe/(Ba plus La) ratio, Saturation magnetization, Coercivity, Barium ferrite, La doping

URI

https://hdl.handle.net/11511/66664

Journal

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

DOI

https://doi.org/10.1016/j.jmmm.2011.02.012

Collections

Department of Physics, Article

Suggestions

OpenMETU
Core

Improved properties of BaFe12O19 prepared by ammonium nitrate melt technique and washed in HCl Topal, Ugur; Ozkan, Husnu; Topal, Kevser Gocmen (2006-09-28) We have synthesized BaFe12O19 samples by ammonium nitrate melt technique (ANMT) at temperatures from 850 to 1200 degrees C. Calcinations at 850-1000 degrees C yield single domain grains having reasonably high coercive fields up to 4500 Oe. Higher temperature calcinations decrease the coercive fields due to multi-domain grain growth. Washing the samples in HCl is effective to reduce the impurities, especially the antiferromagnetic BaFe2O4. HCl-washing increases magnetization by about 50%; the saturation magn...
Enhanced solubility of siloxy-modified polyhedral oligomeric silsesquioxanes in supercritical carbon dioxide Demirtas, Cansu; Dilek Hacıhabiboğlu, Çerağ (Elsevier BV, 2019-01-01) Alkyl siloxy functionalization increases the solubility of polyhedral oligomeric silsesquioxanes (POSS) in supercritical carbon dioxide over an order of magnitude compared to its counterpart with fluoroalkyl groups. The studied component, octatrimethylsiloxy POSS also exhibits higher solubility than other previously studied POSS types with various alkyl and methacryl groups. The octatrimethylsiloxy POSS-CO2 solid-vapor equilibrium curves have been constructed at temperatures between 308 and 328 K by measuri...
Preparation of BaxSr1-xTiO3 thin films by chemical solution deposition and their electrical characterization Adem, Umut; Özenbaş, Ahmet Macit; Department of Metallurgical and Materials Engineering (2003) In this study, barium strontium titanate (BST) thin films with different compositions (Ba0.9Sr0.1TiO3, Ba0.8Sr0.2TiO3, Ba0.7Sr0.3TiO3, Ba0.5Sr0.5TiO3) were produced by chemical solution deposition technique. BST solutions were prepared by dissolving barium acetate, strontium acetate and titanium isopropoxide in acetic acid and adding ethylene glycol as a chelating agent and stabilizer to this solution, at molar ratio of acetic acid/ethylene glycol, 3:1. The solution was then coated on Si and Pt//Ti/SiO2/Si ...
Enhancement of catalytic performance of Ni based mesoporous alumina by Co incorporation in conversion of biogas to synthesis gas ARBAĞ, HÜSEYİN; YAŞYERLİ, SENA; YAŞYERLİ, NAİL; DOĞU, GÜLŞEN; Doğu, Timur (2016-12-05) Mesoporous alumina with an ordered pore structure has significant advantages as a catalyst support in terms of minimization of diffusion limitations and coke formation during reforming reactions. Conversion of biogas to synthesis gas through dry reforming of methane, was investigated over Co & Ni impregnated mono- and bi-metallic mesoporous alumina catalysts with ordered pore structures. Comparison of the results obtained with mesoporous alumina catalysts containing 5% Ni and 2.5% Ni-2.5% Co proved that inc...
Enhancement of biodegradability by continuous ozonation in Acid Red-151 solutions and kinetic modeling Gokcen, F; Ozbelge, TA (Elsevier BV, 2005-11-15) In this work, continuous ozonation of aqueous Acid Red-151 was performed in a stirred tank reactor at neutral pH and 25 degrees C. The results show that ozonation is capable of a rapid conversion of the Acid Red-151 dye molecule to more biodegradable intermediates up to the ozonation time of 120 min at which the optimum BOD5/COD ratio is obtained. The peak BOD5/COD ratios were found to be in the range of 0.028-0.35 for the initial dye concentrations being in the range of 1000-100 mg/L, respectively.

Citation Formats

H. Sozeri, İ. KÜÇÜK, and H. Ozkan, “Improvement in magnetic properties of La substituted BaFe12O19 particles prepared with an unusually low Fe/Ba molar ratio,” JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, pp. 1799–1804, 2011, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/66664.