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，稀土金属的获取成为工业界的一个严重问题。在未来的某个时候，开发不使用重稀有元素的高性能磁体将非常重要。事实上，我们应该考虑用丰富的碳、氮、氧、氢、硫、铁等元素来制造高性能材料。那么，有机铁磁体就是满足上述需求的候选材料。自1991年发现第一个有机铁磁体p-NPNN以来，已经合成了30多种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铁磁相互作用普遍较弱，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，报道了一种构建基于分子的亚铁磁体的新方法，该亚铁磁体具有强反铁磁相互作用并且具有高转变温度。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，则离子晶体中的亚铁磁性将获得理想的分子排列。我们在离子晶体 BBDTA_2ReBr_6 中证明了低于 12. 2 K 的亚铁磁有序性，该晶体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。尽管与传统的基于分子的亚铁磁体相比，磁转变温度相对较低，但我们相信这种利用库仑相互作用的新方法将有助于构建亚铁磁材料。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。上述方面将引起材料科学各个领域读者的兴趣。