The hexagonal BaGd x Fe 12- x O 19 ( x =0.1～1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of...The hexagonal BaGd x Fe 12- x O 19 ( x =0.1～1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of the solution, the molar ratio of nitrate/citric acid and the calcination temperature on the synthesis of the ferrites were investigated. The crystal structure, grain size, shape and magnetic properties were studied by means of XRD, TEM and vibrating sample magnetometer.The results show that under the conditions of pH 7.0 or so, mole ratio of citrate/nitrate (1～3) and calcination temperature of 850 ℃ for 1 h, M type BaGd x Fe 12- x O 19 ultrafine powders with a particle size of less than 100 nm can be obtained, and the coercive force reaches 430 kA·m -1 at x =1.0, which is far greater than that of barium ferrite (BaFe 12 O 19 ).展开更多
The hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic pro...The hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic properties of powders were respectively studied by means of X-ray diffractometer (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450–850 °C with different mole ratio of Nd to Ba (0.1–1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1–3) and calcination temperature of 850 °C for 1 h, M-type BaNd x Fe12?x O19(x=0.1?1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m?1 at x=1, which is far greater than that of barium permanent ferrite (BaFe12O19).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
文摘The hexagonal BaGd x Fe 12- x O 19 ( x =0.1～1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of the solution, the molar ratio of nitrate/citric acid and the calcination temperature on the synthesis of the ferrites were investigated. The crystal structure, grain size, shape and magnetic properties were studied by means of XRD, TEM and vibrating sample magnetometer.The results show that under the conditions of pH 7.0 or so, mole ratio of citrate/nitrate (1～3) and calcination temperature of 850 ℃ for 1 h, M type BaGd x Fe 12- x O 19 ultrafine powders with a particle size of less than 100 nm can be obtained, and the coercive force reaches 430 kA·m -1 at x =1.0, which is far greater than that of barium ferrite (BaFe 12 O 19 ).
文摘The hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic properties of powders were respectively studied by means of X-ray diffractometer (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450–850 °C with different mole ratio of Nd to Ba (0.1–1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1–3) and calcination temperature of 850 °C for 1 h, M-type BaNd x Fe12?x O19(x=0.1?1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m?1 at x=1, which is far greater than that of barium permanent ferrite (BaFe12O19).
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. [
