Department of Physics, Central Michigan University, Mt. Pleasant, Michigan 48859, USA.
Phys Rev Lett. 2010 Oct 29;105(18):185501. doi: 10.1103/PhysRevLett.105.185501. Epub 2010 Oct 26.
Free-standing BiFeO3 perovskite particles with a size ranging from polycrystalline bulk down to 5 nm have been studied by high-energy resonant (Bi K edge) x-ray diffraction coupled to differential atomic pair distribution function analysis. Nanosized BiFeO3 particles are found to exhibit extra, i.e., beyond the usual thermal, structural disorder that increases progressively with diminishing their size. In particles of size smaller than approximately 18 nm the disorder destroys the structural coherence of the Bi sublattice and disturbs that of the Fe-based sublattice in the perovskite structure, substantially affecting the magnetoelectric properties it carries. The new structural information helps better understand the unusual behavior of perovskites structured at the nanoscale.
通过高能共振（Bi K 边缘）X 射线衍射与差分原子对分布函数分析相结合，研究了尺寸从多晶块体到 5nm 的独立型 BiFeO3 钙钛矿颗粒。研究发现，纳米级 BiFeO3 颗粒表现出额外的、即超出通常热结构无序的结构无序，这种无序随着颗粒尺寸的减小而逐渐增加。在尺寸小于约 18nm 的颗粒中，无序破坏了 Bi 亚晶格的结构相干性，并扰乱了钙钛矿结构中基于 Fe 的亚晶格的结构相干性，这对其磁电性能产生了重大影响。新的结构信息有助于更好地理解纳米尺度结构的钙钛矿的异常行为。
