Samples in the system BaTi1-xFexO3-x/2, with x = 0.1 to 0.6, were synthesized at 1200 to 1300C under reducing conditions of O fugacity. After drop quenching, samples were characterized by using the electron microprobe, X-ray diffraction and Mössbauer spectroscopy. All samples were hexagonal with a 6H-BaTiO3 type structure. Mössbauer spectroscopy showed all Fe to be present as Fe3+, occurring in octahedral and pentahedral sites. Analysis of area ratios indicated that O vacancies were distributed randomly over O1 sites, and that a random distribution of Fe and Ti cations over M1 and M2 sites was consistent with the data. No evidence for ordering of O vacancies was found. Results were consistent with conductivity results, which show generally increasing ionic conductivity with increasing O vacancy concentration.

A Mössbauer Study of Oxygen Vacancy and Cation Distribution in 6H-BaTi1-xFexO3-x/2. E.Mashkina, C.McCammon, F.Seifert: Journal of Solid State Chemistry, 2004, 177[1], 262-7