MAGNETISM AND STRUCTURE OF ALKALI-LOADED ZEOLITE LTA

碱负载LTA沸石的磁性和结构

• 批准号: 12640355
• 负责人: MANIWA Yutaka
• 金额: $ 2.69万
• 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: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640355/
• 关键词: zeolite; ferromagnetism; NMR; mass density wave; orbital order; XRD; magnetism

K-ion type zeolite LTA (K_<12>Al_<12>Si_<12>O_<48>(H_2O)_n, which is abbreviated to K_<12>-LTA), is one of synthetic hydrated aluminosilicates. Its framework consist of SiO_4 and AlO_4 tetrahedra sharing the oxygen atom each other and forms two kinds of cage called α and β. These cages are nested each other and form a cubic lattice with a lattice constant 1.23nm. It was found that this system undergoes a phase transition to a ferromagnetic (FM)-like state below around 7K when additional K-atoms are loaded into well-dehydrated K-ion type LTA. K_x/K_<12>-LTA, where x is the number of additional K atoms per α- (or β-) cage. We investigated the structure and magnetism in this system. The main results are summarized below.1. Magnetic and structural phase diagram was established in loading density 0< x<7 and temperature rage 2K<T<500K.2. We performed ^<29>Si-NMR and μSR experiments in K_x/K_<12>-LTA. The data clearly showed the magnetic transition as bulk properties.3. We proposed the most probable magnetic structure which is a canted type II antiferromagnetism in face centered cubic lattice with spin S=1.4. We discovered a new thermally chromatic phenomenon in Na-type zeolite FAU.

K-离子型沸石Lta(K_&lt；12&gt；Al_&lt；12&gt；Si_&lt；12&gt；O_&lt；48&gt；(H_2O)_n，是一种人工合成的水化铝硅酸盐，简称K&lt；12-Lta)。它的骨架由SiO_4和AlO_4四面体组成，相互共享氧原子，形成两种笼状结构，分别称为α和β。这些笼子相互嵌套，形成立方晶格，点阵常数为1.23 nm。研究发现，当K原子被负载到脱水程度较好的K-离子型LTA中时，该体系在7K左右发生了向类铁磁(FM)态的相变。K_x/K_&lt；12-lta，其中x是每个α-(或β-)笼中额外的K原子数。我们研究了该体系的结构和磁性。主要研究结果总结如下：1。在加载密度为0&lt；x&lt；7，温度范围为2K&lt；T&lt；500K时，建立了磁性相图和结构相图。我们在K_x/K_&lt；12&gt；-LTa中进行了^&lt；29&gt；Si-核磁共振和μ顺磁共振实验。数据清楚地显示了磁化转变为块体性质。我们提出了自旋为1.4时，面心立方晶格中最可能的磁结构是倾斜的II型反铁磁性。我们在Na型分子筛FAU中发现了一个新的热色现象。

项目成果

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H.Tou 等人：“(NH_3)K_3C_<60> 中 Mott-Hubbard 定位的 NMR 证据”Phys.Rev.B.

H. Kira et al.: "Magnetic properties of K-absorbing Zeolite LTA"AIP Conf. Proc.. 590. 525-528 (2001)

H. Kira 等人：“吸钾沸石 LTA 的磁性”AIP Conf。

Y. Maniwa et al.: "NMR studies of alkali-doped C_<60> polymers"AIP Conf. Proc.. 590. 443-446 (2001)

Y. Maniwa 等人：“碱掺杂 C_ 60 聚合物的 NMR 研究”AIP Conf.

H.Kira et al.: "Magnetic properties of K-absorbing Zeolite LTA"AIP Conf. Proc.. 590. 525-528 (2001)

H.Kira 等人：“吸钾沸石 LTA 的磁性”AIP Conf.

H.Sakamoto et al.: "NMR studies of silicon clathrate compounds"AIP Conf. Proc.. 590. 503-506 (2001)

H.Sakamoto 等人：“硅笼形化合物的 NMR 研究”AIP Conf.