Origin of anion order in TiOF

TiOF adopts the rutile structure on average, but exhibits local anion ordering through fac-TiO3F3 octahedra. The slightly shorter Ti-O bond results in displacements of Ti3+ cations roughly along the rutile c-axis; we have previously characterised this displacement using single crystal diffuse scattering on ID11. Recent simulations have suggested that this Ti displacement should persist to extremely high temperature; the goal of this experiment is therefore to determine whether this is the case experimentally in order to better understand how anion ordering arises in this and similar anion-ordered materials.