| Abstract: | Contributions to the study of Inorganic Nonstoichiometric Compounds. X. Thermal Behaviour of Metastable H-Ta2O5 Variants in the system Ta2O5- TiO2 Quenched samples of the high temperature form of Ta2O5 with Ti contents of 0 until 6.7 at-% (ΣMe = 100%) were investigated in the metastable region from 20 to 1400°C with a continuously registrating guinier-camera which was equiped with a special sample heating device: There are 3 roomtemperature-phases: H(triclinic), H1(monoclinic), H2(monoclinic), and 3 high temperature phases: H′ (triclinic), H2′ (monoclinic) and H3(tetragonal). In the regions between H and H1 as well as H1 and H2 diagrams of both phases could be observed together on the X-ray photograph; these regions disappeare at temperatures higher than approximately 310°C. With increasing temperatures the following phase transitions occure: H → H′ → H2′ → H3, H1 → H → H2′ → H3, H2 → H1 → H2′ → H3, H2 → H2′ → H3. Electronmicroscopic investigations of a sample with 6.7 at-% Ti gave no indication to the existence of “shear planes”. By means of the present results various possibilities of the incorporation of Ti in the H-Ta2O5 lattice are discussed. |
