采用水热法合成了M型Sr Fe12O19铁氧体粉末,并对其烧结前后的结构和磁性能进行了研究。实验发现,无论烧结前还是后样品都是单相铁氧体结构。烧结后,样品的矫顽力和饱和磁化强度分别从42.9 k A/m和48.1 emu/g显著增加到237.8 k A/m和64.9...采用水热法合成了M型Sr Fe12O19铁氧体粉末,并对其烧结前后的结构和磁性能进行了研究。实验发现,无论烧结前还是后样品都是单相铁氧体结构。烧结后,样品的矫顽力和饱和磁化强度分别从42.9 k A/m和48.1 emu/g显著增加到237.8 k A/m和64.9 emu/g,这与高温烧结后其晶粒的长大密切相关。实验还发现,烧结后样品中存在着剩磁增强效应,其原因可归于样品中不同磁硬度的纳米晶相之间的磁耦合作用。展开更多
In this paper, the nanometer permanent magnetic BaFe12O19 powder was synthesized by a novel method of independent nucleation and crystallization steps and subsequent heat treatment,during the synthesis, Ba(NO3)2, Fe(N...In this paper, the nanometer permanent magnetic BaFe12O19 powder was synthesized by a novel method of independent nucleation and crystallization steps and subsequent heat treatment,during the synthesis, Ba(NO3)2, Fe(NO3)2 and NH4HCO3·NH2COONH4 were used as starting materials. The effect of crystallization process and heat treatment conditions on the particle size, microstructure and magnetic properties of powder was studied by using XRD, TEM and vibration sample magnetometometer techniques.XRD results showed that the hematite, α Fe2O3, was the main phase in the powder at heat treatment temperatures below 650℃ and its amount in the powder was decreased with increasing temperature and small amount of α Fe2O3 was still remained after being heated at 900℃ for 8hrs. BaFe12O19 was formed about 650℃ and its amount increased in the powder as temperature raised and the higher temperature was needed to attain considerable amount of BaFe12O19 and ideal nanometer BaFe12O19 particle in the powder. The temperature between 40℃～60℃ in the crystallization process was favor to the formation of good BaFe12O19 crystal and to the good magnetic properties of the powder. TEM showed that the particle size in the powder increased with the enhancement of the temperature and the powder crystallized at 40℃ and heated at 800℃ for 8hrs afterwards had a very homogenous particle size distribution, and that the powder heated at 900℃ for 8hrs with the same crystalline condition as the former had a typical hexagonal shape and a chain aggregation. Specific saturation and residential magnetizations and coercive force of the powder increased monotonically with the increase of temperature, and reached 39.86A·m2·kg-1, 23.96A·m2·kg-1, 480kA·m-1 at 900℃, respectively.展开更多
文摘采用水热法合成了M型Sr Fe12O19铁氧体粉末,并对其烧结前后的结构和磁性能进行了研究。实验发现,无论烧结前还是后样品都是单相铁氧体结构。烧结后,样品的矫顽力和饱和磁化强度分别从42.9 k A/m和48.1 emu/g显著增加到237.8 k A/m和64.9 emu/g,这与高温烧结后其晶粒的长大密切相关。实验还发现,烧结后样品中存在着剩磁增强效应,其原因可归于样品中不同磁硬度的纳米晶相之间的磁耦合作用。
文摘In this paper, the nanometer permanent magnetic BaFe12O19 powder was synthesized by a novel method of independent nucleation and crystallization steps and subsequent heat treatment,during the synthesis, Ba(NO3)2, Fe(NO3)2 and NH4HCO3·NH2COONH4 were used as starting materials. The effect of crystallization process and heat treatment conditions on the particle size, microstructure and magnetic properties of powder was studied by using XRD, TEM and vibration sample magnetometometer techniques.XRD results showed that the hematite, α Fe2O3, was the main phase in the powder at heat treatment temperatures below 650℃ and its amount in the powder was decreased with increasing temperature and small amount of α Fe2O3 was still remained after being heated at 900℃ for 8hrs. BaFe12O19 was formed about 650℃ and its amount increased in the powder as temperature raised and the higher temperature was needed to attain considerable amount of BaFe12O19 and ideal nanometer BaFe12O19 particle in the powder. The temperature between 40℃～60℃ in the crystallization process was favor to the formation of good BaFe12O19 crystal and to the good magnetic properties of the powder. TEM showed that the particle size in the powder increased with the enhancement of the temperature and the powder crystallized at 40℃ and heated at 800℃ for 8hrs afterwards had a very homogenous particle size distribution, and that the powder heated at 900℃ for 8hrs with the same crystalline condition as the former had a typical hexagonal shape and a chain aggregation. Specific saturation and residential magnetizations and coercive force of the powder increased monotonically with the increase of temperature, and reached 39.86A·m2·kg-1, 23.96A·m2·kg-1, 480kA·m-1 at 900℃, respectively.
