退火温度对方形FePt纳米颗粒磁性及微结构影响

Effects of annaling temperature on the magnetic and microstructural properties of cubic FePt nanoparticles

利用高温液相直接合成出了尺寸为7nm具有立方形状的FePt纳米颗粒，研究了样品在不同温度退火后的磁性和微结构．X射线衍射结果表明，当样品经500℃退火1h后，样品开始由无序的fcc结构转变为有序的fct结构．随着退火温度的上升，样品的有序度S和矫顽力也逐渐增大，当退火温度为570℃时，样品的有序度就达到了0.88，7nmFePt颗粒的有序化温度明显低于3～4nmFePt颗粒．

7nm FePt nanoparticles with cubic shape were synthesized by high temperature solution phase method. Both magnetic properties and microstructure of FePt films annealed at temperatures between 500℃-650℃ were investigated. X-ray diffraction results showed that the chemical ordered （fct） FePt phase was formed in the sample annealed at 500℃ for lh. The ordering parameter and coercivity increased with increasing annealing temperature. It can be summarized that 7nm as-synthesized FePt nanoparticles exhibited lower ordering temperature than 3-4rim FePt nanoparticles.