Our in-situ high-pressure x-ray diffraction measurements on zircon structured nanocrystalline chromates show that the structural phase transformation from zircon to scheelite phase proceeds via an intermediate monoclinic phase, i.e., $\text{zircon}\to \text{monoclinic}\to \text{scheelite}$. Though there have been speculations about zircon-scheelite phase transformation proceeding through an unstable transient monoclinic phase in ${\text{ZrSiO}}_4$, we have experimentally demonstrated the existence of a similar intermediate stable state in a zircon structured compound. For our nanocrystalline samples, the transformation pressure is found to be higher than the bulk.

• Received 16 December 2009

DOI:https://doi.org/10.1103/PhysRevB.81.104109