LAUSR

Abstract Two polymorphs of ammonium trifluorooxovanadate (NH4VOF3) were synthesized as single crystals by the reaction of ammonium metavanadate with vanadium in hydrofluoric acid. The two phases crystalize in the same space group (Pbam), have similar unit cell volumes (α-NH4VOF3:371 A3, β-NH4VOF3:375 A3 at 100 K), and similar total energies (difference of ∼2.2 meV per formula unit at 0 K). Both structures contain the [VOF3]nn− ladder motif that has been reported in phases such as KVOF3 and RbVOF3. The polymorphs are differentiated by the angle between two neighboring ladder motifs. Although the two polymorphs are structurally similar, selective synthesis is possible as longer reaction times favor β-NH4VOF3.