Pressure-induced structural transitions and metallization in hollow ZnMn2O4 microspheres

High-pressure in situ angle dispersive X-ray diffraction (ADXRD) measurements combined with first-principles calculations were performed on hollow ZnMn2O4 microspheres up to 43.5 GPa at room temperature, and two high-pressure phases emerged at 15.9 GPa. Phase III was assigned to the CaMn2O4 type structure (space group Pbcm). It is supposed that phase II probably has a MgAl2S4 inverted spinel type structure (space group Imma). Moreover, phase I, phase II and phase III were probably coexisted when pressure was released. The compressional behaviors of phase I (space group I4(1)/amd) and phase III were all determined. Besides, based on electronic band structure calculations, it was uncovered that phase I probably experiences a pressure-induced electronic topological transition (ETT) to a semimetallic state upon pressure, and phase III is a semimetallic state. Our results show that pressure play a dramatic role in tuning ZnMn2O4's crystalline structures, electrical behavior and spin-state. (C) 2019 Elsevier B.V. All rights reserved.