Impurities in Perovskites: Evidence from ESR of Posistor Barium Titanate Ceramics

Influence of mechanical activation on the structure of ultrafine BaTiO3 powders

“…Some authors whose examinations included EPR spectra at room temperature and above, attributed a peak at g = 1.97 to the localized Ti 3+ states [16]. Others emphasized that this and similar values of the g-factor (g = 1.963-1.975) should be ascribed to the Ti 3+ -V O , that is Ti 3+ -F + centers, rather than exactly to Ti 3+ [21][22][23][24]. These observations of Ti 3+ and Ti 3+ -V O signals at room temperature and above strongly contradict the reports of a different group of authors, where manifestation of the Ti 3+ ion in EPR spectra was observed only at rather low temperatures (below 250 K [17], even mostly below 80 K [18][19][20]).…”

“…Dunbar et al [29] and Castro et al [30] considered just the doped ceramic. On the other hand, several authors reported that the EPR peak with g ≈ 1.97 may be caused by intrinsic Ti 3+ related defects in BaTiO 3 [16][17][18][19][20][21][22][23][24] . A few of them observed this peak just in reduced BaTiO 3 ceramic [20,25].…”