Defect chemistry of Ti-doped antiferroelectric Bi_(0.85)Nd_(0.15)FeO_3

摘要

Aberration corrected scanning transmission electron microscopy revealed that Bi_(0.85)Nd_(0.15)Fe_(0.9)Ti_(0.1)0O_3 ceramics contain coherent Nd-rich precipitates distributed throughout the perovskite lattice,, implying charge compensation is obtained by the creation of V_(Nd)~Ⅲ and not V_(Bi)~Ⅲ. At low concentrations, therefore, Ti~(4+) replace Fe~(2+) with the creation of 2/3V_(Nd)~Ⅲ, and at higher concentrations (when Fe~(2+) have been eliminated and the conductivity suppressed), Fe~(3+) with the creation of 1/3V_(Vd)~Ⅲ. The switch in ionic compensation mechanism from 2/3V_(Nd)~Ⅲ at low Ti concentrations (~1%) to 1/3V_(Nd)~Ⅲ at higher concentrations (>1%) results in a decrease in the magnitude of·△T_C/△x, as the disruption of long range anti-polar coupling declines.