The crystal structure of high temperature phase Ta2O5

The high temperature phase of Ta₂O₅ and its variants were maintained in a pure Ta₂O₅ specimen using the conventional solid-state reaction method and the advanced laser irradiation technique. The structure of the high temperature phase is determined to be tetragonal with lattice parameters of a = 3.86 Å and c = 36.18 Å and space group of I4₁/amd. Compared to the previously reported crystal structure, the number of the total basis atoms was reduced to be 6 from 11. The modified crystal structure interprets well the recorded high-resolution electron microscopy images and the selected area electron diffraction patterns. Based on the basic tetragonal structure, the crystal lattice structures of the orthorhombic and monoclinic variants were determined and the corresponding space groups were analyzed according to the variation of the symmetrical elements. In addition, crystal atomic structures of these two variants were proposed based on the tetragonal structure.