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Organic Radical Based Magnetic Materials with Strong Intermolecular Magnetic Interactions

具有强分子间磁相互作用的有机自由基磁性材料

基本信息

批准号：
21550138
负责人：
FUJITA Wataru
金额：
$ 3.08万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2009
资助国家：
日本
起止时间：
2009 至 2011
项目状态：
已结题

项目摘要

Recently acquirement of rare earth metals in industrial circles grows into a serious problem. At some future date, it will be important to develop high performance magnets without use of heavy rare elements. In fact we should consider that we make the high performance materials from abundant elements such as carbon, nitrogen, oxygen, hydrogen, sulfur, iron, etc. Then, there are organic ferromagnets as candidate for materials satisfying the above demand. Since the first organic ferromagnet, p-NPNN, was found in 1991, more than 30 organic ferromagnets with intermolecular ferromagnetic interactions have been synthesized. However, their Curie temperatures of molecule-based ferromagnets with the ferromagnetic ordered state remained low because intermolecular ferromagnetic interactions were generally weak in organic magnetic materials. In this study, a new approach to construction of molecule-based ferrimagnets which have strong antiferromagnetic interactions and which have high transition temperatures is reported. In an ionic crystal, cations and anions are usually aligned alternatively due to the Coulomb's interaction. If the spin multiplicity of the cation will be different from that of the anion, desirable molecular alignment from ferrimagnetism in ionic crystals will be obtained. We demonstrated ferrimagnetic ordering below 12. 2 K in an ionic crystal, BBDTA_2ReBr_6, consisted of an organic radical cation BBDTA^+(S=1/2) and a transition metal anion ReBr_6^<2->(S=3/2). Although the magnetic transition temperature is relatively low, compared to those of traditional molecule-based ferrimagnets, we believe that this new approach using the Coulombic interactions will be useful for the construction of ferrimagnetic materials. Combination of various magnetic cations and anions will give rise to ferrimagnets with high transition temperature. The above aspects will attract the interest of readers working in the various fields on materials science.

近年来，稀土金属在工业界的获取成为一个严重问题。在未来的某个日期，开发不使用重稀有元素的高性能磁体将是重要的。事实上，我们应该考虑，我们从丰富的元素，如碳，氮，氧，氢，硫，铁等，使高性能材料，那么，有有机铁磁体作为候选材料满足上述要求。自1991年发现第一个有机铁磁体p-NPNN以来，已经合成了30多个具有分子间铁磁相互作用的有机铁磁体。然而，由于有机磁性材料中分子间的铁磁相互作用通常较弱，因此具有铁磁有序态的分子基铁磁体的居里温度仍然较低。在这项研究中，一种新的方法来构建分子基亚铁磁体，具有强的反铁磁相互作用，并具有高的转变温度的报告。在离子晶体中，由于库仑相互作用，阳离子和阴离子通常交替排列。如果阳离子的自旋多重性与阴离子的自旋多重性不同，则将获得离子晶体中亚铁磁性的理想分子排列。我们证明了亚铁磁有序低于12。在离子晶体BBDTA_2ReBr_6中，由有机自由基阳离子BBDTA^+（S=1/2）和过渡金属阴离子ReBr_6^<2->（S=3/2）组成。虽然磁转变温度相对较低，与传统的分子基亚铁磁体相比，我们相信，这种新的方法使用库仑相互作用将是有用的亚铁磁性材料的建设。各种磁性阳离子和阴离子的结合将产生具有高转变温度的亚铁磁体。以上几个方面将引起从事材料科学各领域工作的读者的兴趣。