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热磁测量,包括高温磁化率和高温磁化强度测量,是根据热磁曲线转折点的温度(居里点、尼尔点或相变点)鉴定样品中磁性矿物种类的有效方法.本文选取两个人工合成磁赤铁矿样品,利用四种热磁测量仪器分析不同的条件下测得的热磁曲线.依据样品与空气接触程度,将测量环境设为开放、封闭、封闭(通入氩气或氮气)三类.结果表明:热磁测量环境的开放程度对居里点和曲线可逆程度产生极大的影响.封闭环境下测得的居里点较开放环境下的低,分别对应磁铁矿和磁赤铁矿;开放系统的热磁曲线不可逆程度高于封闭系统.造成这些差异的原因是氧化还原条件的不同.本文的磁赤铁矿样品在封闭的条件下,加热至250℃左右开始转化为磁铁矿,因此无法通过居里点被正确识别;在开放的氧化环境下,加热的最终产物为赤铁矿,能够测得正确的居里点.本实验结果启发人们:在不同的加热环境下,磁性矿物可能表现出不同的热磁行为,根据单一的热磁曲线,很容易对样品中磁性矿物的种类造成误判.全面对比不同条件下的测量结果,才能够得出更为准确的结果.
Thermomagnetic measurements, including high temperature magnetic susceptibility and high temperature magnetization measurements, are effective methods to identify the types of magnetic minerals in a sample based on the temperature (Curie point, Neil point, or phase transition point) at the point where the thermomagnetic curve is turning.This paper selects two artificial According to the degree of sample contact with air, the measurement environment is set as open, closed and closed (with argon or nitrogen gas being introduced) ) .The results show that the degree of openness of thermomagnetic measurement environment has a great influence on the Curie point and the curve reversibility.The Curie point measured in the closed environment is lower than that in the open environment and corresponds to the magnetite and Maghemite; the irreversible degree of thermal magnetic curve of the open system is higher than that of the closed system.The reason of these differences is due to the difference of redox conditions.In this paper, the maghemite sample is transformed to a temperature of about 250 ℃ under closed conditions Is magnetite and therefore can not be correctly identified by the Curie point; the end product of heating in an open oxidizing environment is hematite, which measures the correct Curie point.The results of this experiment inspire people to: , The magnetic minerals may exhibit different thermal magnetic behaviors under the heating environment, and according to a single thermomagnetic curve, it is easy to misjudge the types of magnetic minerals in the sample. A comprehensive comparison of the measurement results under different conditions can yield more For accurate results.