Fig. 5: Real-space charge mapping and EELS analysis of LaCoO3 and the three P-HEOs.

a Charge mapping of the three P-HEOs, indicating a decrease of the covalency and increase of the ionicity of TM–O bond. The colored lines in the line profiles of the charge distribution show the variation along the lines (Top line and Bottom line) as indicated in the charge maps. b EELS of LaCoO3 and the three P-HEOs. c Detailed EELS of O K-edge electron energy-loss near-edges structures of the four samples. The dash line in (c) is a guide to eye showing the right shift of the lowest-energy O K peaks.