Unique hyper-kagome atomic order in the noncentrosymmetric structure of Na3Ir3O8

Resumo

The formation of a unique hyper-kagome atomic order in the structure of the ordered spinel phase Na₃Ir₃O₈ has been analyzed in terms of the Landau theory of phase transitions. We have identified a critical six-component order parameter generating a phase transformation of the spinel parent phase to ordered P4₁32 (P4₃32) spinel-like enantiomorphs and examined the structural mechanism behind the development of hyper-kagome order and the detailed crystal chemistry of Na₃Ir₃O₈.