The microstructure and characteristics of pre-sintered strontium ferrite powder were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The present study shows that t...The microstructure and characteristics of pre-sintered strontium ferrite powder were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The present study shows that the pre-sintered strontium ferrite powder is provided with a certain particle size distribution, which results in high-density magnets. The strontium ferrite particle has a laminar hexagonal structure with a size similar to ferrite single domain. Ferric oxide phase due to an incomplete solid phase reaction in the first sintering is discovered, which will deteriorate the magnetic properties of ferrite magnet. In addition, the waste ferrite magnets with needle shape arranging along C axis in good order into the powders are found, which have no negative effects on finished product quality.展开更多
Sintered permanent magnetic strontium ferrites were studied using transmission electron microscopy to investigate the microstructure morphology and its correlation with the magnetic properties. The present study shows...Sintered permanent magnetic strontium ferrites were studied using transmission electron microscopy to investigate the microstructure morphology and its correlation with the magnetic properties. The present study shows that the microstructure of sintered permanent magnetic strontium ferrites is an important parameter in determining their magnetic properties. The microstructure morphology in low-performance ferrite magnet is obviously different from high-performance one. The magnetic properties of sintered permanent strontium ferrite depend strongly on the orientation degree of strong magnetic crystals. The presence of ferric oxide phase in ferrite magnet can deteriorate the magnetic properties. Moreover, proper quantities of crystal defects are beneficial to high coercive force due to the fixing of magnetic domain.展开更多
The hexagonal BaLa x Fe 12- x O 19 fine powders with M type structure were synthesized by sol gel method. The pH of the solution, the molar ratio of nitrate to citric acid and the calcination temperature were investig...The hexagonal BaLa x Fe 12- x O 19 fine powders with M type structure were synthesized by sol gel method. The pH of the solution, the molar ratio of nitrate to citric acid and the calcination temperature were investigated to clarify the forming conditions of the ferrites. The crystal structure, grain size, form and magnetic properties were studied by means of XRD, SEM and vibrating sample magnetometer. It is concluded that at pH of 7.0 or so, molar ratio of nitrate to citric acid of 1/3 and calcination temperature of 850 ℃(1 h), 1 000 ℃, M type BaLa x Fe 12- x O 19 fine powders with a particle size of less than 300 nm was obtained. [展开更多
基金This work was financially supported by the Key Technologies R&D Program of Guangdong Province, China (No. 2004B10301009).
文摘The microstructure and characteristics of pre-sintered strontium ferrite powder were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The present study shows that the pre-sintered strontium ferrite powder is provided with a certain particle size distribution, which results in high-density magnets. The strontium ferrite particle has a laminar hexagonal structure with a size similar to ferrite single domain. Ferric oxide phase due to an incomplete solid phase reaction in the first sintering is discovered, which will deteriorate the magnetic properties of ferrite magnet. In addition, the waste ferrite magnets with needle shape arranging along C axis in good order into the powders are found, which have no negative effects on finished product quality.
基金This work was financially supported by the Key Technologies R&D Program of Guangdong Province, China (No. 2004B10301009).
文摘Sintered permanent magnetic strontium ferrites were studied using transmission electron microscopy to investigate the microstructure morphology and its correlation with the magnetic properties. The present study shows that the microstructure of sintered permanent magnetic strontium ferrites is an important parameter in determining their magnetic properties. The microstructure morphology in low-performance ferrite magnet is obviously different from high-performance one. The magnetic properties of sintered permanent strontium ferrite depend strongly on the orientation degree of strong magnetic crystals. The presence of ferric oxide phase in ferrite magnet can deteriorate the magnetic properties. Moreover, proper quantities of crystal defects are beneficial to high coercive force due to the fixing of magnetic domain.
文摘The hexagonal BaLa x Fe 12- x O 19 fine powders with M type structure were synthesized by sol gel method. The pH of the solution, the molar ratio of nitrate to citric acid and the calcination temperature were investigated to clarify the forming conditions of the ferrites. The crystal structure, grain size, form and magnetic properties were studied by means of XRD, SEM and vibrating sample magnetometer. It is concluded that at pH of 7.0 or so, molar ratio of nitrate to citric acid of 1/3 and calcination temperature of 850 ℃(1 h), 1 000 ℃, M type BaLa x Fe 12- x O 19 fine powders with a particle size of less than 300 nm was obtained. [
