Formation of rutile-type Ta(IV)O 2 by shock reduction and cation-deficient Ta 0.8O 2 by subsequent oxidation

Abstract

Ta 2O 5 is reduced to Ta(IV)O 2 with the rutile structure by shock-loading to 50–60 GPa. Tetragonal unit cell parameters at room conditions are measured to be a = 4.7518(5)Å, c = 3.0878(4) Å, c a = 0.6498(1) , and V = 69.72(1) Å 3. The chemical composition is thermogravimetrically determined to be Ta 0.97±0.04O 2 by heating shock-reduced products in an oxygen gas flow to 1200°C. In the oxidation process a cation-deficient rutile-type compound Ta 0.8O 2 is found to be metastably formed.