Temperature-driven evolution of hierarchical nanodomain structure in   tetragonal-like BiFeO3 films
  Transmission electron microscopy study of tetragonal-like BiFeO3 films reveals a hitherto unreported hierarchical nanodomain structure. The 30-50 nm wide stripe domains with {110} domain walls consist of a substructure of lamellar nanodomains of 8-10 nm width in a herringbone-like arrangement. In situ heating and cooling reveals a reversible transition from the hierarchical nanodomain structure to a tweed-like domain structure which is accompanied by a first-order phase transition near 120 {\deg}C with a thermal hysteresis. 
Yajun Qi, Zuhuang Chen, Lihua Wang, Xiaodong Han, Junling Wang,   Thirumany Sritharan, Lang Chen
cond-mat.mtrl-sci