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

1970; The National Institute of Standards and Technology; Volume: 74A; Issue: 4 Linguagem: Inglês

10.6028/jres.074a.037

2376-5704

R.S. Roth, J.L. Waring, W.S. Brower,

Metallurgical Processes and Thermodynamics

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 Å, c ≈ 35.68 Å. 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.