Dy掺杂对Sr_2Bi_4Ti_5O_(18)铁电陶瓷性能的影响

Effect of Dy-doping on the properties of Sr_2Bi_4Ti_5O_(18) ferroelectric ceramics

用传统固相烧结法制备了Sr2Bi4-xDyxTi5O18(SBDT-x,x=0—0.20)陶瓷样品.x射线衍射分析表明,微量的Dy掺杂没有影响Sr2Bi4Ti5O18(SBTi)原有的层状钙钛矿结构.通过研究样品的介电特性,发现Dy掺杂减小了材料的损耗因子,降低了样品铁电-顺电相转变的居里温度.铁电性能测量结果表明,随Dy含量的增加,SBDT-x系列样品的剩余极化先增大,后减小.当Dy掺杂量为0.01时,剩余极化达到最大值,约为20.1μC·cm-2.掺杂引起剩余极化的变化,与材料中缺陷浓度、内应力以及晶格畸变程度等因素有关,是多种作用机理相互竞争的结果.(Bi2O2)2+层通常被看作是绝缘层和空间电荷库,对材料的铁电性能起关键作用.掺杂离子进入(Bi2O2)2+层会导致铁电性能变差.

Ferroelectric Sr2Bi4-xDyxTi5O18 （SBDT-x, x=0-0.20） ceramic samples were prepared using the conventional solid-state reaction method, x-ray diffraction patterns （XRD） of SBDT-x ceramics show that doping with a small amount of Dy does not change the crystal structure of Sr2Bi4Ti5O18 （SBTi）. Their Curie temperature （Tc） and dielectric loss （tanδ） decrease with Dy doping amount. The remnant polarization （2Pr） of SBDT-x increases at first, then decreases with increasing of Dy content. When Dy content is 0.01, the 2Pr reaches a maximum value of 20.1 μC·cm^-2 . The variation of 2Pr for SBDT-x relates to space charge density, internal strain and structure distortion. （Bi2O2）^2＋ layer acting as an insulating layer and space charge storage plays an important role in their ferroelectric properties in BLSFs. The incorporation of doping ions into （Bi2O2）^2＋ layer may destroy its original function and deteriorate the ferroelectric property.