Reversibility of phase transition from T-Li₃MCl₆ to S-Li₃MCl₆. XRD patterns of (a) T-Li₃YCl₆ and (b) T-Li₃HoCl₆ before and after annealing at 595 and 573 K for 50 h. A decrease in the intensity of the 101 peaks of T-Li₃HoCl₆ upon annealing indicated the formation of the S-phase. Arrows indicate the broad peaks, which are possibly the stacking faults along the c-axis.