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Microstructure and magnetic properties of BaFe12O19 powder

Nowosielski R., Babilas R., Dercz G., Pająk L., Skowroński W.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 27, nr 1

51-54

EN

Purpose: Analysis of microstructure and magnetic properties of BaFe12O19 powder obtained by milling and annealing of Fe2O3 and BaCO3 precursors. Design/methodology/approach: The mixture of iron oxide (Fe2O3) and barium carbonate (BaCO3) powders was used to obtain BaFe12O19 powder by using high-energy ball milling and heat treatment processes. The X-ray diffraction methods were used for qualitative, quantitative phase analyses and for crystallite size and lattice distortion determination. The thermal properties of the studied powders were analyzed using the differential thermal analysis (DTA). The magnetic properties of examined powder material were studied by resonance vibrating sample magnetometer (R-VSM). The size of powder particles was determined by a laser particle analyzer. Findings: The milling process of iron oxide and barium carbonate mixture causes decrease of the crystallite size of involved phases. The X-ray diffraction investigations of Fe2O3 and BaCO3 mixture milled for 50 hours and annealed at 850, 900, 950 and 1000*C enabled the identification of hard magnetic BaFe12O19 phase and also small amount of Fe2O3 phase. The magnetic properties of studied powders are dependent on temperature of their annealing. The sample annealed at 1000*C has the best hard magnetic properties from all studied samples. The content changes of hard magnetic phase (BaFe12O19) with the increase of annealing temperature results in the improvement of hard magnetic properties. Practical implications: The BaFe12O19 powder can be suitable component to produce sintered hard magnetic materials. Originality/value: The study results of BaFe12O19 powders confirm the utility of applied investigation methods in the microstructure and magnetic properties analysis of powder materials.

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Microstructure and magnetic properties of commercial barium ferrite powders

Nowosielski R., Babilas R., Wrona J.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

307-310

EN

Purpose: Microstructural and magnetic properties analysis of commercial barium ferrite powder BaFe12O19. Design/methodology/approach: The X-ray diffraction methods were utilized not only for qualitative and quantitative phase analysis of studied powder sample, but also for the determination of lattice parameters, crystallite size and the lattice distortion. The Rietveld method was used in the verification of the qualitative phase composition and in the determination of phase abundance. Hill and Howard procedure was applied for quantitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The morphology of barium ferrite powders was analyzed using the scanning electron microscopy (SEM) method. The distribution of powder particles was determined by a laser particle analyzer. Moreover, the magnetic hysteresis loop of examined powder material were measured by resonance vibrating sample magnetometer (R-VSM). Findings: The X-ray diffraction analysis revealed the presence of hexagonal BaFe12O19 and rhombohedral Fe2O3 phases in examined powder samples. The barium ferrite phase appeared to be the main component of the samples (97.8 wt.%). The crystallite size of BaFe12O19 phase is above 100 nm. The size of studied powders is in the range from 0.2 to 40.5 micrometres. The arithmetic mean diameter of BaFe12O19 powders population is 10.335 micrometres. The SEM images showed irregular shape and size of powder particles. The coercive force (HC) obtained from hysteresis loop has a value about 159 kA/m. Practical implications: Structure analysis of commercial barium ferrite powder is helpful to prepare this material by laboratory methods. Originality/value: The obtained results of investigations by different methods of structure characterization confirm their utility in the microstructure analysis of powder materials.

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Barium ferrite powders prepared by milling and annealing

Nowosielski R., Babilas R., Dercz G., Pająk L., Wrona J.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 22, nr 1

45-48

EN

Purpose: Microstructure and magnetic properties analysis of barium ferrite powder obtained by milling and heat treatment. Design/methodology/approach: the milling process was carried out in a vibratory mill, which generated vibrations of the balls and milled material in side the container during which their collisions occur. After milling process the powders were annealed in electric chamber furnace. The X-ray diffraction methods were used for qualitative phase analysis of studied powder samples. The distribution of powder particles was determined by a laser particle analyser. The magnetic hysteresis loops of examined powder material were measured by resonance vibrating sample magnetometer (R-VSM). Findings: The milling process of iron oxide and barium carbonate mixture causes decrease of the crystallite size of involved phases. The X-ray investigations of tested mixture milled for 30 hours and annealed at 950 degrees centigrade enabled the identification of hard magnetic BaFe12O19 phase and also the presence of Fe2O3 phase in examined material. The Fe2O3 phase is a rest of BaCO3 dissociation in the presence of Fe2O3, which forms a compound of BaFe12O19. The best coercive force (HC) for mixture of powders annealed at 950 degrees centigrade for 10,20 and 30 hours is 349 kA/m, 366 kA/m and 364 kA/m, respectively. The arithmetic mean of diameter of Fe2O3 and BaCO3 mixture powders after 30 hours of milling is about 6.0 micrometres. Practical implications: The barium ferrite powder obtained by milling and annealing can be suitable components to produce sintered and elastic magnets with polymer matrix. Originality/value: The results of tested barium ferrite investigations by different methods confirm their utility in the microstructure and magnetic properties analysis of powder materials.

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Structure and properties of barium ferrite powders prepared by milling and annealing

Nowosielski R., Babilas R., Dercz G., Pająk L., Wrona J.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 12

735-742

EN

Purpose: Microstructure and magnetic properties analysis of barium ferrite powder obtained by milling and heat treatment Design/methodology/approach: The milling process was carried out in a vibratory mill, which generated vibrations of the balls and milled material inside the container. After milling process the powders were annealed in electric chamber furnace. The X-ray diffraction methods were used for qualitative phase analysis of studied powder samples. The morphology of Fe2O3 and BaCO3 powders after milling was analyzed using the scanning electron microscopy (SEM) method. The distribution of powder particles was determined by a laser particle analyzer. The magnetic hysteresis loops of examined powder material were measured by resonance vibrating sample magnetometer (R-VSM). Findings: The milling process of iron oxide and barium carbonate mixture causes decrease of the crystallite size of involved phases and leads to increase the content of Fe2O3 phase and decrease of BaCO3 content. Milling process causes enriching of surface layer of powder particles by Fe2O3. The X-ray investigations of tested mixture milled for 30 hours and annealed at 950*C enabled the identification of hard magnetic BaFe12O19 phase and also the presence of Fe2O3 phase in examined material. The Fe2O3 phase is a rest of BaCO3 dissociation in the presence of Fe2O3, which forms a compound of BaFe12O19. The best coercive force for the mixture of powders annealed at 950oC for 10, 20 and 30 hours is 349 kA/m, 366 kA/m and 364 kA/m, respectively. From morphology images and distribution of powder particle size it can be concluded, that the size of tested powder particles increases with increasing time of milling process. The increase of milling time up to 20 hours leads to joining of smaller particles in bigger ones; agglomerates are formed. Practical implications: The barium ferrite powder obtained by milling and annealing can be suitable component to produce sintered and elastic magnets with polymer matrix. Originality/value: The results of tested barium ferrite investigations by different methods confirm their utility in the microstructure and magnetic properties analysis of powder materials.