EPR EVIDENCE FOR COMPENSATING DEFECTS IN BATIO3 GRAIN-BOUNDARY BARRIER LAYER CAPACITORS

BaTiO3 ceramics are doped with SiO2, Nb2O5, Dy2O3 and LiF and then sintered in various a tomspheres. Electron paramagnetic resonance (EPR) spectroscope is employed to study the possible defects in the BaTiO3 grain boundary barrier layer (GBBL) capacitors. EPR results suggest the existence of VBa' defects. VBa' The enhanced EPR signal at 140°C for undoped BaTiO3 is due to the increase of VBa resulting from tetragonal to cubic phase transformation. Neutral VBa and doubly ionized V″Ba vacancies may be present as a result of electron transfer with VBa. It is argued that diffusion of metal ions affects the oxidation of the grain boundary layer of GBBL BaTiO3, capacitors. © 1990.