(Bi,La)_4Ti_3O_(12)Sr(Bi,La)_4Ti_4O_(15)共生结构铁电材料性能研究

A study on the properties of (Bi,La)_4Ti_3O_(12)Sr(Bi,La)_4Ti_4O_(15) intergrowth ferroelectrics

采用固相烧结工艺 ,制备了不同La掺杂量 (x =0 0 0 ,0 2 5 ,0 50 ,0 75 ,1 0 0 ,1 2 5和 1 50 )的 (Bi,La) 4 Ti3 O1 2 Sr(Bi,La) 4 Ti4O1 5(SrBi8-xLaxTi7O2 7)共生结构铁电陶瓷样品 .用x射线衍射对其进行微结构分析 ,并测量铁电、介电性能 .结果发现 ,La掺杂未改变Bi4Ti3 O1 2 SrBi4Ti4O1 5共生结构铁电材料的晶体结构 .随掺杂量的增加 ,样品的矫顽场(Ec)略有增加 ,剩余极化 (2Pr)先增大 ,后减小 .在x =0 50时 ,2Pr 达到极大值 ,为 2 5 6 μC·cm-2 ,与Bi4Ti3 O1 2 SrBi4Ti4O1 5相比 ,2Pr 增加了近 60 % ,而Ec 仅增加约 1 0 % .随La掺杂量的增加 ,样品的居里温度TC 逐渐降低 ,x =0 50时 ,TC=556℃ .在x=1 50时 。

Lanthanum-doped intergrowth ferroelectrics: (Bi, La)(4)Ti3O12Sr(Bi, La)(4)Ti4O15 (SrBi8-xLaxTi7O27) (x = 0.00, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50) ceramic samples have been prepared by solid-state reaction method. Their structure was analyzed by x-ray diffraction, and their dielectricity and ferroelectricity were measured. It is found that La doping does not change the crystal structure of Bi4Ti3O12-SrBi4O15. The coercive field ( E-C) of SrBi8-xLaxTi7O27 increases slightly and the remnant polarization (2P(x)) increases at first, then decreases with the increase of La content. The 2P(x) reaches a maximum value of 25.6 muC.cm(-2) when x is 0.50. The 2P(x) increases nearly 60%, but the E-C increases only about 10%, compared with those of SrBi8Ti7O27. Their temperatures of phase transition (T-C) decrease with La doping. The T-C of SrBi7.5La0.50Ti7O27 is 556 degreesC and shows good thermal stability. As x becomes 1.50, the SrBi7.5La0.50Ti7O27 exhibits a characteristic of relaxor ferroelectrics.