Spin-lattice relaxation tiroes of 1H, 27Al, and 29Si spins in kaolinites with various origins have been measured at room temperature. Relaxation by paramagnetic impurities is dominant in those spins. Spin diffusion plays an important role in the 1H and 27Al relaxations, and their relaxations belong to the diffusion-limited case. 29Si spins relax through the dipole-dipole interaction with electron spins directly, and the contribution of the spin diffusion is negligible. A part of the electron spins having an ESR signal at g = 4.1 play the role of relaxation centers. We have analyzed the relaxation times theoretically and have estimated the concentrations of paramagnetic impurities and the spin-lattice relaxation time of the electron spins.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry