Neutron total scattering studies on A-site disorder in lead-free ferroelectric Bi-0.5(Na1-xKx)(0.5)TiO3

作者：Jeong Ilkyoung^*; Park Chang Yeol; Kim Dong Jin; Kim Sun hwa; Moon Byung Kee; Kim Won III; Ahn Chang Won

来源：Zeitschrift fur Kristallographie, 2011, 226(2): 150-154.

DOI：10.1524/zkri.2011.1295

• Lead-free ferroelectrics
• A-site disorder
• Neutron total scattering
• PDF analysis
• RMC modeling

We performed neutron total scattering measurements on lead-free ferroelectric Bi-0.5(Na1-xKx)(0.5)TiO3 (x = 0.0, 0.25) and present local structures of A-site (Bi3+, Na+/K+) ions using reverse Monte Carlo modeling. The A-site incorporation of large K+ ions suppresses the tilting of oxygen octahedra and strongly influences the off-center displacement of A-site ions. As a result, we found that the Bi-O bond length redistributes between x = 0.0 and x = 0.25. Compared to the Bi-O bond, the distribution of Na/K-O bond length was broader and smeared. Thus, the interplay between Bi3+ and K+ ions plays a key role in ferroelectric response near morphotropic phase boundary. For the Ti-O bond-length distribution, we found little change between the two compositions despite the long-range symmetry difference. This result suggests that A-site and B-site off-center displacements are decoupled.

• 出版日期2011