Post-spinel-type AB2O4 high-pressure phases in geochemistry and materials science

Post-spinel-type AB2O4 compounds are stable at higher pressures than spinel phases. These compounds have garnered much interest in geo- and materials science for their geochemical importance as well as potential application as high ionic conductors and materials with strongly correlated electrons. Here, large-volume high-pressure syntheses, structural features and properties of post-spinels are reviewed. Prospects are discussed for future searches for post-spinel-type phases by applying advanced large-volume high-pressure technology. Post-spinel transition-metal oxides have emerged as potential candidates for high ionic conductors and materials with strongly correlated electrons. In this Review, the authors discuss recent developments in large-volume high-pressure technology, crystal structural features of post-spinel phases and their geochemical significance, and weigh the challenges and opportunities post-spinel phases entail for material applications.