Study of the structural phase transitions in RbCuCl3 and CsCuCl3 single crystals with the electric-magnetic-type interactions using a R87b and C133s nuclear magnetic resonance spectrometer

RbCuCl 3 and CsCuCl3 single crystals were grown by the slow evaporation method, and the spin-lattice relaxation times and the resonance lines of the R87b and C133s nuclei in the resulting crystals were investigated using Fourier transform nuclear magnetic resonance (FT NMR) spectrometry. The temperature dependence of the relaxation time of the R87b nucleus in the RbCuCl3 crystals exhibited a discontinuity near TC2(=260 K), which was attributed to a structural phase transition. Although the R87b relaxation data showed no change indicative of a phase transition at TC1(=340 K), the splitting of the R87b resonance lines did change abruptly at TC1, indicating that the R87b nuclei depends on the local environments surrounding these nuclei. For the CsCuCl3 crystals, the relaxation time of the C133s nucleus underwent large, abrupt changes at TN (=10.5 K) and near TC (=423 K), which coincide with a magnetic and a structural phase transition, respectively. The RbCuCl3 and CsCuCl3 results are compared with those obtained previously for other ABCl3 (A=Rb, Cs, B=Cd, Mn) perovskite crystals.