Oxidation states of titanium in bulk barium titanates and in (100) fiber-textured (Ba{sub x}Sr{sub 1-x})Ti{sub 1+y}O{sub 3+z} thin films.
Chemical shifts of titanium L edges and oxygen K edges in electron energy-loss spectroscopy in transmission electron microscopy were used to detect valence state reduction of Ti in bulk barium titanates, used as reference materials, and in (Ba{sub x}Sr{sub 1-x})Ti{sub 1 + y}O{sub 3 + z} (BST) thin films grown with excess Ti. A hollandite-type Ba titanate, containing Ti with an average valence state of approximately 3.7 in octahedral coordination, showed large chemical shifts relative to rutile TiO{sub 2} and BaTiO{sub 3}, containing only Ti{sup 4+}. In BST, chemical shifts relative to BaTiO{sub 3} were measured from grain interiors of columnar films with different amounts of excess Ti. We found that shifts, corresponding to an average valence state of Ti smaller than nominal 4+, increase with increasing amounts of excess Ti in the films. The results show that at least some amount of excess Ti is accommodated in these films by a defect mechanism that requires a reduction of the average valence state of Ti.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF); OUS
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 949437
- Report Number(s):
- ANL/MSD/JA-40906; APPLAB; TRN: US1003533
- Journal Information:
- Appl. Phys. Lett., Vol. 79, Issue 19 ; Nov. 5, 2001; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- ENGLISH
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