Characterization of defect structure in acceptor-modified piezoelectric ceramics by multifrequency and multipulse electron paramagnetic resonance spectroscopy

The defect chemistry in the vicinity aliovalent acceptor-type transition-metal functional centers in piezoelectric perovskite oxides is characterized by means of multifrequency and multipulse electron paramagnetic resonance spectroscopy, assisted by density-functional theory calculations. The focus is on the formation of charged (Fe-Zr,Fe-Ti' - V-O(center dot center dot))(center dot) and neutral (Cu-Zr,Cu-Ti - V-O(center dot center dot))(x) defect dipoles, which are discussed causing internal bias fields, as well as isovalent manganese substitutes. Based on this nanoscale characterization of the defect structure, its impact on macroscopic material properties is discussed.