Nd掺杂对Bi_4Ti_3O_(12)铁电薄膜的微结构和铁电性能的影响

Effects of neodymium doping on microstructures and ferroelectric properties of bismuth titanate ferroelectric thin films

利用溶胶-凝胶法在Pt/Ti/SiO2/Si(100)衬底上制备了Nd掺杂Bi4Ti3O12(Bi4-xNdxTi3O12,x=0.00,0.30,0.45,0.75,0.85,1.00,1.50)铁电薄膜样品.研究了Nd掺杂对Bi4Ti3O12薄膜的微结构和铁电性能的影响.研究结果表明:Nd掺杂未改变Bi4Ti3O12薄膜的基本晶体结构.在掺杂量x<0.45时,Nd3+只取代类钙钛矿层中的A位Bi3+.当x=0.45时,样品剩余极化强度达最大值,在270kV.cm-1的电场下为32.7μC.cm-2.掺杂量进一步增加时,结构无序度开始明显增大,Nd3+开始进入(Bi2O2)2+层,削弱其绝缘层和空间电荷库的作用,导致材料剩余极化逐渐下降.当掺杂量x达到1.50时,掺杂离子最终破坏(Bi2O2)2+层的结构,材料发生铁电-顺电相变.

The Bi4-x Ndx Ti3 O12 （ x = 0.00,0.30,0.45,0.75,0.85,1.00, 1.50） ferroelectric thin films were prepared on the Pt/Ti/ SiO2/Si（100） substrates using sol-gel method. The effeet of neodynium doping on the mierostructures and ferreeleetrie properties of films were studied. The experimental results show that Nd^3＋ only substitutes Bi^3＋ in the pseudo-perovskite block when Nd content x is lower than 0.45. When Nd content x is about 0.45, the film has the largest remnant polarization （2Pr） of 32.7μC·cm^-2 at an applied field of about 270 kV· cm^-1. At x 〉 0.45, part of Nd ions are incorporated into the （Bi2O2 ）^2＋ block, which would change the mierostrueture of （Bi2 O2 ）^2＋ block and weaken its functions as the insulating layer and the space charge storage, resulting in the decrease of the 2Pr. When x = 1.50, the dopout would destroy the structure of （Bi2O2 ）^2＋ block, which leads to ferroeleetrie-paraeleetrie phase transition of the film