Further exploring the structural changes observed upon heating, variable temperature PXRD analysis of GUF-14 (Figure ) shows a gradual decline in the intensity of (101) Bragg peak, eventually resulting in its disappearance when heated at 498 K for 16 h, together with all other peaks of mixed hkl character. This transition is irreversiblecooling to room temperature does not indicate any structural reversion -and is attributed to the delamination of the stacked layers seen in SEM images, resulting in the transition to a hns phase.