Measurements of magnetic properties of natural rock-forming minerals under pressure

天然造岩矿物在压力下的磁特性测量

基本信息

批准号：
17540398
负责人：
KODAMA Kazuto
金额：
$ 1.73万
依托单位：
Kochi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17540398/
关键词：
AC susceptibility ferromagnetic mineral pressure temperature magnetite Curie temperature 磁性

项目摘要

We have aimed to conduct a laboratory experiment for measuring alternating-current (AC) magnetic susceptibility and its temperature dependence under pressure around one GPa. For this purpose, we have developed a small, c. 70mm long, devise that consists of primary and secondary coils for measuring mutual inductance, a heater coil and a thermocouple, all of which are molded with heat-resistive cement. Then, the coil system is placed within a laboratory-made piston cylinder that can give rise to hydrostatic pressure by means of a handy, uni-axial press. We have carried out a series of experiments for characterizing magnetic behaviors of the coil system at an atmospheric pressure. We have used Nickel as a test sample and succeeded in measuring magnetic susceptibility change with temperature, whereby detecting a ferromagnetic phase transition with Tc equivalent to that of Nickel (631K). Then, we have measured fragments of a natural volcanic rock that contains pure magnetite as a sole magnetic carrier. We could detect Tc of magnetite (853K). These results show that the new coil system would be useful for not only detecting Tc, but also investigating changes in AC magnetic susceptibility with frequency. The latter could provide a new means for estimating grain size as well as identifying magnetic minerals in natural rocks. We finally carried out a series of experiments using Nickel by pressurizing at c. 10 MPa. The results appear to be successful, reproducing Tc of Nickel, but also show it still hard to make precise measurements of AC susceptibility under pressure. We should point out that a solid media should be used as a pressure transmitter, instead of BN powder used in this study, in order to avoid break-down of the coil system caused by the greater volume change of BN with the more pressurized.

我们的目的是进行实验室实验，以测量交替电流（AC）磁敏感性及其在一个GPA附近的压力下的温度依赖性。为此，我们开发了一个小的c。长70毫米，设计由用于测量相互感应的初级和次级线圈组成，加热器线圈和热电偶，所有这些都以耐热水泥成型。然后，将线圈系统放置在实验室制造的活塞缸中，该缸可以通过方便的单轴压力机通过方便的，单轴压力引起静水压力。我们已经进行了一系列实验，以表征大气压力下线圈系统的磁性行为。我们已经使用镍作为测试样本，并成功地测量了温度的磁化率变化，从而检测了与镍（631K）相当的TC的铁磁相变。然后，我们测量了一个天然火山岩的碎片，该岩石包含纯磁铁矿作为唯一磁载体。我们可以检测到磁铁矿（853K）的TC。这些结果表明，新的线圈系统不仅可用于检测TC，还可以调查AC磁敏感性随频率的变化。后者可以提供一种新的手段，用于估计晶粒尺寸以及识别天然岩石中的磁性矿物质。最终，我们通过在C处加压进行了一系列实验。 10 MPA。结果似乎是成功的，重现了镍的TC，但也表明很难在压力下精确测量AC易感性。我们应该指出，应将固体介质用作压力发射器，而不是本研究中使用的BN粉末，以避免由BN较大的体积变化引起的线圈系统破裂，而加压越来越大。