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Temperature dependences of NMR spectra have been observed for 23Na and 27Al in the metallic phase of Na–K form low silica X (LSX) zeolite loaded with potassium, where the condition of saturation is achieved with a loading level of 9.0 atoms per supercage and the paramagnetic moment contributes to the magnetism of the system beyond simple isolated spin. Two separated peaks have been recognized for 23Na, where the shift values show a quite linear relationship with susceptibility, and the so-called K–χ plot works quite well to give values of 0.32 kOe μB−1 and 0.40 kOe μB−1 for hyperfine coupling constants. Although no separated peak is seen in the 27Al NMR spectrum, the spectral centroid deviates to the positive side. The shoulder of the spectrum scales to susceptibility and the K–χ plot also works well to give a value of 0.15 kOe μB−1 for the hyperfine coupling constant. The orbital of potassium-originated electrons confined in the cage of LSX is understood as seeping out over the framework of zeolite, which is wider than that of the sodium-originated case. [ABSTRACT FROM AUTHOR]

We report a23Na and27A1 nuclear magnetic resonance (NMR) investigation of low-silica X(LSX) zeolite with chemical formula Na12Al12Si12O48(Na12-LSX) loaded with n additional guest sodium atoms. Nan /Na12-LSX exhibits an insulator-to-metal transition around n=11.6, which is accompanied by a significant enhancement of bulk magnetic susceptibility. Paramagnetic moments are in the metallic Na12/Na12-LSX thermally activated with an activation energy of around 0.1 eV. Simultaneously a new shifted component appears in the23 Na NMR, whose large and positive NMR shift scales with bulk magnetic susceptibility. Its spin-lattice relaxation rate 1/ T1 is governed by the local-field fluctuations characterized by the same activation energy as obtained from the bulk magnetic susceptibility data. The time scale of these fluctuations is typical for atomic motions, which suggest strong electron-phonon coupling, a hallmark of polaron states. The insulator-to-metal transition in Nan/Na12-LSX is thus discussed within a polaron model. [ABSTRACT FROM AUTHOR]