Ji Kunlang, Solana-Madruga Elena, Patino Midori Amano, Shimakawa Yuichi, Attfield J Paul
Centre for Science at Extreme Conditions (CSEC), School of Chemistry, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3FD, UK.
Dpto. Q. Inorgánica, Universidad Complutense de Madrid, Avda. Complutense sn, 28040, Madrid, Spain.
Angew Chem Int Ed Engl. 2022 Jul 4;61(27):e202203062. doi: 10.1002/anie.202203062. Epub 2022 Apr 21.
Cation ordering in solids is important for controlling physical properties and leads to ilmenite (FeTiO ) and LiNbO type derivatives of the corundum structure, with ferroelectricity resulting from breaking of inversion symmetry in the latter. However, a hypothetical third ABO derivative with R32 symmetry has never been observed. Here we show that Co InSbO recovered from high pressure has a new, ordered-R32 A BCO variant of the corundum structure. Co InSbO is also remarkable for showing two cation redistributions, to (Co In ) CoSbO and then Co InSbO variants of the ordered-LiNbO A BCO structure on heating. The cation distributions change magnetic properties as the final ordered-LiNbO product has a sharp ferrimagnetic transition unlike the initial ordered-R32 phase. Future syntheses of metastable corundum derivatives at pressure are likely to reveal other cation-redistribution pathways, and may enable ABO materials with the R32 structure to be discovered.
固体中的阳离子有序排列对于控制物理性质很重要，并导致刚玉结构的钛铁矿（FeTiO₃）和铌酸锂型衍生物，后者因反演对称性破缺而产生铁电性。然而，一种具有R32对称性的假设性第三种ABO₃衍生物从未被观测到。在此我们表明，从高压下恢复的CoInSbO₃具有一种新的、有序的-R32刚玉结构的A₂BCO变体。CoInSbO₃还因其在加热时表现出两种阳离子重新分布而引人注目，即转变为有序的铌酸锂型A₂BCO结构的(CoIn)₂CoSbO₃变体，然后再转变为CoInSbO₃变体。阳离子分布改变了磁性，因为最终的有序铌酸锂产物具有与初始有序-R32相不同的尖锐亚铁磁转变。未来在高压下合成亚稳刚玉衍生物可能会揭示其他阳离子重新分布途径，并可能使具有R32结构的ABO₃材料被发现。
