Fig. 3: Topotactic phase transition in C30/Tn.
From: Three dimensional band-filling control of complex oxides triggered by interfacial electron transfer
a Schematic crystal structure of perovskite LaCoO3, La3Co3O8, and brownmillerite La2Co2O5, respectively. Enlarged details are presented to show the stacking sequence of CoO6 octahedrons and CoO4 tetrahedrons along the out-of-plane direction. b X-ray diffraction data of LCO/LTO heterostructures. Blackline, C30/T0; orange line, C28/T7; magenta line, C30/T10; light blue line, C30/T15. All indices correspond to the averaged perovskite u.c. Peaks from STO substrates are denoted by asterisks. c High-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of C30/T15 taken along the STO [110] direction. The scale bar corresponds to 0.5 nm. The inset image shows a simulated STEM image viewed along the [001]o direction based on the structure of brownmillerite La2Co2O5. The yellow dashed line indicates the LCO/LTO interface, while the red dashed line shows the region used to calculate La–La interatomic distances. d Out-of-plane La–La distance along the red dashed line shown in c. The error bar shows the standard deviations of the averaged measurements. The cyan dotted line and green dashed line indicates the out-of-plane lattice parameter of LaCoO3 (C30/T0) and La2Co2O5 (C30/T15) obtained from b, respectively.
