Русский 
English 
Synthesis of new classes of compounds can lead to discoveries of novel physical phenomena as well as innovative applications. Fe4O5 is the first member of a very recently discovered family of iron oxides that can be synthesised only under high-pressure conditions. A multi-technique study of Fe4O5 reveals that it undergoes a unique charge-ordering transition below 150 K that involves competing dimeric and trimeric ordering within the chains of Fe ions. This electronic transition drives an intricate incommensurate distortion in its crystal structure.