Influence of non-stoichiometry on the ferroelectric aging properties of Mn-doped BaTiO_3 ceramics

摘要

In the present work, the effect of the non-stoichiometry on the dielectric and ferroelectric properties especially the aging phenomenon of Ba-m(Ti0.995Mn0.005)O-3 ceramics is studied. With the A/B site stoichiometry ratio m increased from 0.990 to 1.010, the Curie temperature is decreased from 128 to 118 degrees C monotonically. The non-stoichiometry shows the dramatic effect on the aging phenomenon of the Mn-doped BaTiO3 ceramics. As the aged sample with m1, an obvious constriction of hysteresis loop and recoverable electro-strain curve are observed. With m increased to 0.997, the recoverable electro-strain shows the highest value of 0.17%, whereas for the m1 samples, it shows the normal hysteresis loop and electro-strain curve as the un-aged samples. The valence state analysis of Mn ions shows that for the m1 and m=1 samples only Mn2+ ions exist, while for the m1 samples Mn2+ and Mn4+ ions co-exist. Moreover, with m decreasing, the amount of Mn2+ ions increases. It is proposed that the non-stoichiometry affects the valence state of Mn ions, which causes the number of oxygen vacancies to change, ultimately affecting the aging effect of the Mn-doped BaTiO3 ceramics.