Effect of oxide additions on the polymorphism of tantalum pentoxide. II. ""Stabilization"" of the high temperature structure type

Abstract

The high temperature, apparently tetragonal, polymorph of tantalum pentoxide can be obtained at room temperature by quenching a specimen containing 2-5 mole percent of the following oxides: SnO2, Ga2O3, Cr2O3, Fe2O3, Sc2O3, or MgO. All the x-ray patterns can be indexed on a body centered tetragonal cell with a ? 3.830 ?, c ? 35.68 ?. However, P2O5, V2O5, Nb2O5, ZrO2, Lu2O3, NiO, or ZnO do not stabilize the tetragonal form at room temperature. Single crystals of scandium 'stabilized' Ta2O5, have been grown by the Czochralski technique.