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Published on: May 15, 2017
Pressure-Induced Phase Transitions in Bilayer La3Ni2O7
Mingyu Xu1, Greeshma C Jose2, Aya Rutherford3
1Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States.
None:
La3Ni2O7 differs from expectations in part because at ambient pressure, it exists in two polymorphs: an unconventional crystal structure with alternating layers of single- and triple-layered nickel-oxygen octahedra (i.e., La2NiO4 plus La4Ni3O10, with the so-called 1313 crystal structure) and a classical double-layer Ruddlesden-Popper phase (i.e., La3Ni2O7, with the so-called 2222 crystal structure, which dominates at high pressure). In this study, we report the pressure-dependent structural and electrical resistive properties of single crystals of the classical double-layered La3Ni2O7, grown at slightly elevated pressure using the floating-zone method. Structural characterization under pressures up to 15.4 GPa reveals a gradual transition from orthorhombic to tetragonal symmetry that is completed at 12-14 GPa. Additionally, we present pressure and field-dependent electrical resistance measurements up to 27.4 GPa, from which we construct a phase diagram. Although a resistive transition at 80 K is observed at high pressures, the resistive hallmarks of superconductivity are not.
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