Charge ordered states in La1-xSrxFeO3

The presence of complex charge ordering (CO) phenomena in La1-xSrxFeO3 (0 less than or equal to x less than or equal to 0.7) has been revealed by transmission electron microscopy at low temperatures. In La0.7Sr0.3FeO3 (x = 0.3) the precursory CO reflections become visible as streaks at similar to 250 K upon cooling. Below 150 K these streaks condense to sharp spots at the systemic (1/2,0,0) positions. The real-space images are suggestive of charge segregation occurring at low temperatures. At high doping levels (0.5 less than or equal to x less than or equal to 0.7), the CO has been observed in the [111](p) direction below similar to 200 K. In particular, the results obtained La0.3Sr0.7FeO3 (x = 0.7) can be well understood in terms of CO in sequence ... Fe3+Fe3+Fe5+Fe3+Fe3+Fe5+ ..., as proposed previously.