摘要
为充分拓展DSC测量功能、探寻居里温度的简便测量方法、尤其是探寻高温居里温度的耐久测量方法,对真空电弧熔炼(Nd,Pr)12.8Dy0.2Fe77.4Co4B5.6铸锭,先通过PPMS测量升温速率3 K·min-1时样品的M-T曲线,并用外推法得到居里温度为648.3 K;然后采用DSC分别以3,10,20,30,40 K·min-1速率测量样品的升、降温曲线,分析升、降温曲线上对应吸、放热峰的起始点、峰值、终止点的特征温度值;再分别用最小二乘法拟合特征温度与升降温速率的直线方程,计算升降温速率分别为0和3 K·min-1时特征温度值,并与PPMS测量的居里温度值进行比较。结果表明:由DSC升温曲线起始点的特征温度拟合直线方程计算的升温速率为3 K·min-1的特征温度值为649.1 K,与PPMS外推法得到的居里温度相对差值最小为0.12%,具有足够的精确度。
In order to expand the function of differential scanning calorimeter, and to explore the simpler measuring method of Curie temperature, even the more durable method of higher Curie temperature, comparative studies were done, at Curie temperature of （Nd, Pr）12.8Dy0.2Fe77.4 Co4B5.6 ingot measured respectively by PPMS and DSC. For magnetization-temperature curve measured with PPMS at the heating rate of 3 K·min-1, and at magnetic field of 500 Oe, the Curie temperature was determined as 648.3 K by extrapolation. And firstly the DSC heating and cool- ing curves of the ingot were measured at the rate of 3, 10, 20, 30, and 40 K.min-1 respectively. The curves at the rate of 3 and 10 K.min-1 were both straight lines in the range of 293 -823 K. Secondly their initial points, peak temperatures and terminal ones of the corresponding endothermic, and exothermic curve were surveyed. Thirdly u- sing the least square method, the straight lines were fitted of the characteristics temperatures separately. Fourthly the characteristic temperatures at 0 and 3 K·min-1, were calculated, and fifthly they were compared with Curie temperature measured by PPMS. The results showed that the initial point of the fitted line, at the rate of 3 K·min-1 , of DSC heating curves is 649.1 K, the relative difference with the Curie temperature measured by PPMS extrapolation method is 0. 12%, with sufficient accuracy.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2014年第5期548-554,共7页
Journal of the Chinese Society of Rare Earths
基金
国家自然科学基金项目(51174121和51274125)
浙江省重点科技创新团队项目(2010R50016-30)资助
