Research Of Aging Effect In Barium Titanate Based Ferroelectric Ceramics

In this work, lead-free Ba0.77Ca0.23TiO3(BCT) ceramics were prepared by solid–state reaction method. The aging effect of Mn doped BCT with different substituted positions was investigated.The experimental results show that with the increase of aging time, Ba0.77Ca0.23Ti0.99Mn0.01O3(BCT-B) ceramics aged 10 days have double hysteresis loops. However, no obvious aging effect is obtained in the(Ba0.77Ca0.23)0.99Mn0.01TiO3(BCT-A) ceramics. These results are caused by that the B-site substituted ceramics have oxygen vacancy, whereas A-site substituted have no oxygen vacancy. In addition, because of the defect dipole orientation after aging, the electrical properties of BCT-B ceramics changes with aging time. Tc of the BCT-B after aged 30 days is ~1 oC higher than that of the counterpart aged 1 day. Both the d33 and kp decrease with the increment of aging time,d33 decreases from 91 to 80 pC/N, and kp decreases from 22% to 13%. The mechanical quality factor Qm significantly increases as the aging time increases from the initial 245 to the final 1500.The present work studies the sintering art for BT ceramics, and found purity of raw powders and sintering time have an important effect on the ceramics. For BT ceramics sintered at 1350 oC for 4 hours, its piezoelectric and ferroelectric properties were better than others with different prepared process, moreover experienced an aging effect. At the same time, the BT ceramics have a weakly magnetic.In addition, Ba0.85Ca0.15Zr0.1Ti0.9O3(BCZT),(Ba0.85Ca0.15)(Zr0.1Ti0.9)0.99Mn0.01O3(BCZT-Mn) and(Ba0.85Ca0.15)(Zr0.1Ti0.9)0.99Co0.01O3(BCZT-Co) ceramics were also successfully prepared. The hysteresis loops of fresh and aged 33 days at 1 Hz for BCZT ceramics were measured. The loops changed little with aging time and no formation of double hysteresis loops. The poled BCZT ceramics’ Curie temperature is 86 oC, and a obvious dielectric peak appears, and shows that tetragonal-orthogonal transformation temperature is around 32 oC. Both BCZT-Mn and BCZT-Co ceramics have magnetic properties, and they are affected by the doping elements in BCZT ceramics.