Dipolar field contribution to memory echo in piezoelectric powder

摘要

On polarization echoes, dipolar field contribution was considered and the role of the effectively stimulated oscillation mode was investigated. The investigated theory was based on the torque rotation model derived by Melcher and Shiren. The model was developed here by considering the particle behavior under the effectively stimulated oscillation field and the rotation caused by the local field of oscillating dipoles of nearest neighborhood, after taking off the second electric field. As theoretical results, the echo signal was derived as anharmonicity in collection of effectively stimulated oscillations of the dipoles with deviated orientations. The deviated angles of particles due to the local dipolar field were selectively redistributed in accordance with the oscillation modes effectively stimulated by the two‐pulse sequence. Experimental results for read out multipulse echoes were explained by the theoretical calculation, not only for time detection including the image echoes, but also for relaxation characteristics along the time axis.