MAGNETISM AND STRUCTURE OF ALKALI-LOADED ZEOLITE LTA

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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.