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

摘要

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 P4(1)32 (P4(3)32) spinel-like enantiomorphs and examined the structural mechanism behind the development of hyper-kagome order and the detailed crystal chemistry of Na3Ir3O8.