Twin structure by Cs-133 NMR in ferroelastic CsPbCl3 crystal

The twin structure of a ferroelastic CsPbCl3 single crystal grown by the Br idgman method has been investigated using Cs-133 nuclear magnetic resonance . Owing to the quadrupole interaction of the Cs-133 (I = 7/2) nucleus in Cs PbCl3 crystal, two sets of seven-line structures were obtained, instead of a simple seven-line structure. From the experimental data, the quadrupole c oupling constant, e(2)qQ/h, and the asymmetry parameter, eta, for the reson ance lines of two sets were determined. However, the two parameters were fo und to be same. The principal axes X, Y, and Z of the EFG tensor for the Cs -133 were found to lie along the crystallographic c-, a- and b-axes for one set, while the Y and Z axes were interchanged for the other. This indicate s that the CsPbCl3 crystal has characteristics of a twin structure crystal. Therefore, the domain wall makes an angle of 45 degrees with respect to th e [100] axis; we observed the ferroelastic domain with respect to the promi nent W wall. (C) 1999 Elsevier Science Ltd. All rights reserved.