SYNTHESIS PROCESS AND GIANT MAGNETIZATION OF INTERSTITIAL TYPE (Fe、Co)-(B、C、N) SINGLE CRYSTALS

我们研究了在(Fe、Co)-(B、C、N)系统中存在Fe16N_2超结构(α“相)的可能性，它被认为具有巨大的磁化强度(3.0T)，但一直是有争议的、和其他可能的超结构。我们发现，在后一种体系中，B-、-C-、-N原子以间隙方式存在于Fe-、-Co中。Fe倾向于通过夹杂物形成马氏体相，导致磁化强度增加。然而，、没有得到该系统存在超结构的证据。通过发展高精度的X射线分析、、磁化测量和、样品合成方法对Fe-N及其超结构的马氏体相进行研究，得到以下结果：1)通过高精度测定马氏体超结构的比率，我们澄清了马氏体超结构的磁化强度在2.4T-3.0T范围内的任何值，这取决于晶格的变形。到目前为止，许多研究小组报告的所有数据都相互矛盾，可以从晶格形变的角度解释一致性。2)对α的形成过程、热稳定性和由此产生的晶格形变的进一步研究“使我们得出结论：巨磁化很可能是从体心立方结构到面心立方结构形变的结果，而与α有关的磁化强度的很大变化”来自于面心立方Fe中已经发现的“高自旋态和低自旋态”。最后，我们得出结论，、的巨磁化是存在的，它是由在超结构形成过程中施加在晶格上的各向异性应力稳定的，我们可以结束持续了25年的最大的争论之一。

We investigated possibility of existence of Fe16N2 superstructure (alpha" phase)、which has been claimed to have a giant magnetization (3.0 Tesla) but have been controversial、and other thinkable superstructures in (Fe、Co)-(B、C、N) system. We found that in the latter system B、C、N atoms are included in Fe、Co interstitially. Fe tends to form a martensite phase by this inclusion resulting in an increase of magnetization. However、no evidence of superstructure was obtained for this system. Through investigation of the martensite phase of Fe-N and its superstructure by developing high precision method of X-ray analysis、magnetization measurement and sample synthesis、the following results were obtained.1) We clarified by high precision determination of the rate of the superstructure included in the martensite that its magnetization takes any value in a range of 2.4-3.0 Tesla depending sensitively on deformation of the lattice. All data reported up to date by many research group which conflict with each other can be explained consistency in terms of the lattice deformation. 2) Further investigation of formation process、thermal stability and resultant lattice deformation of alpha" led us to the conclusion that it is highly possible that the giant magnetization is a result of the deformation from bcc to fcc like structure and the large variety of magnetization associated with alpha" is from 「the high and low spin state」 which has been found in the fcc Fe.Finally we conclude that the giant magnetization is in existence and it is stabilized by an anisotropic stress imposed on the lattice during formation of the superstructure and we could put an end to one of the largest controversy which lasted for these 25 years.