摘要
菱铁矿经热处理后在室温下测定的等温剩磁曲线形态，与热处理温度有关。经过５００—７００℃温度范围内热处理的样品，等温剩磁曲线呈现与普通铁磁质的等温剩磁曲线不同的特征。反常曲线的详细形态与磁化经历有关。从零剩磁态出发，逐渐增加磁化场直到３００ｍＴ，在几十毫特斯拉段，剩磁出现一个峰，以后逐渐趋于一个稳定值。再来回施加反向和正向外磁场时，在四个象限内出现高度相等的峰。在第一和第三象限内，峰之后为一坪区。坪高与峰高之比与温度和样品形状有关。最小比值达１／２９。出现异常的热处理温度范围与样品成分有关。峰的高度与热处理温度无关，但峰的宽度、位置与温度有关。存在一个；陆界线度，当样品沿磁化场方向的尺寸小于这个临界线度时，不出现异常。实验测得的所有异常曲线的峰高近似相等，与样品的形状和质量关系不大。
he isothermal remanent magnetization(IRM) curves obtained from siderite samplesheated at 500 700℃ have some anormalous characteristics, quite differing from thoseof the known ferromagnetic materials. With increasing applied field, a maximum ofremanent magnetization appears at tens of millitesla, then decreases,followed bya horizontal tail till 300mT. When a negative field is applied subsequently,the intensityof remanence rises to a plus peak first in stead of decreasing,then decreases,changesits sign and passes through a minus peak, followed by a minus horizontal tail finally. All peaks are the same in hight. The hight ratio of the tail to peak depends on thetemperature of heat treatment, whereas the hights of peaks are independent of it.Thereis a critical dimension of salnple. No peak occurs, when the size along the direction ofthe external field is smaller than it. When the remanence is expressed in total magneticmoment of the sample, the hights of peaks are roughly equal each other for all anoma-lous curves. No significant effect of the mass and shape of sample on the value ofpeak is observed.
出处
《北京大学学报（自然科学版）》
CAS
CSCD
北大核心
1994年第1期61-70,共10页
Acta Scientiarum Naturalium Universitatis Pekinensis
基金
国家自然科学基金
关键词
等温剩磁
热处理
菱铁矿
Isothermal remanent magnetization
Anomalous isothermal remanentmagnetization
Siderite
γFe_2O_3
