摘要
磁化率随温度和频率的变化特性(F-T)对于研究超顺磁和单畴磁性颗粒的磁学性质非常有效。文章结合饱和磁化强度和矫顽力随温度变化的特性,依据尼尔理论,探讨了磁性颗粒的粒径分布与其(F-T)特性的关系。结果表明,磁化率的最大值对应于其解阻温度,因此可以用来估算磁性颗粒的平均粒径。随温度变化的频率磁化率曲线可以转化为连续的粒径分布曲线。本方法可以用来模拟自然地质体(例如,火山灰、黄土沉积物)中磁性矿物的粒度分布。
On the basis of the Neel Theory, modeling of the frequency- and temperature-dependency of susceptibility χ（F-T） has become an important method to characterize the superparamagnetism of strongly ferrimagnetic minerals. However, most previous investigations assumed constant values of saturation magnetization （Ms） and microscopic coercivity（Hk）at low temperatures. In this paper, we incorporate temperature-dependency of Ms and Hk at high temperatures. The simulated results with a wide range of coercivity and frequency for both magnetite and maghemite show that for fine-grained magnetic particles： 1 ） the temperature corresponding to the maximum susceptibility is sensitive to grain size, and thus can be used to estimate grain size of fine-grained magnetic particles; 2）temperature-dependency of susceptibility χfd （e. g., χlt- χhf, where χlf and χlf are χ measured at low and high frequencies, respectively）defines the volume percentage spectrum of these fine-grained particles.
出处
《第四纪研究》
CAS
CSCD
北大核心
2007年第6期955-962,共8页
Quaternary Sciences
基金
欧盟Marie-Curie Fellowship(批准号:IIF00755)
国家自然科学基金项目(批准号:40674032
40221402和40325011)
中国科学院知识创新工程项目(批准号:KZCX3-SW-150)资助
关键词
磁化率
岩石磁学
环境磁学
磁化率的温度和频率特性
magnetic susceptibility, rock magnetism, environmental magnetism, temperature and frequency-dependent magnetic susceptibility
