STRUCTURAL PHASE TRANSITIONS IN DONOR DOPED BaTiO3 AND EFFECTS ON PTCR BEHAVIOR

In this study, in situ transmission electron microscopy studies were used to examine and characterize domain formation and phase transformation mechanisms in donor doped, PTCR BaTiO3 materials. A significant and abrupt change in resistivity occurs as a result of a non-uniform boundary structure, the result of variability in strain state and non-uniform potential energy barrier along the grain boundary. In the highly stressed grain boundary regions, the ferroelectric phase transformation is very rapid with martensitic type character. During the phase transfornation process. the sudden release of stress and change in structure. in the limited number of conducting regions along the grain boundary, were found to be the dominant factors behind the driving force for a sudden and abrupt change in resistance.