Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Resistive Switching and the Future in Perovskite Nickelates" By Qi Wang Purdue MSE Preliminary Exam Advisor: Professor Shriram Ramanathan ABSTRACT The resistive switching behavior has attracted lots of attention recently, due to the potential of application in non-volatile memory devices. An electroforming process as a pretreatment is usually necessary and critical. A wide range of materials have been studied, which are mostly transition metal oxides. Resistive switching can be either bipolar switching or unipolar switching depending on the switching mechanisms. There are two main mechanisms: One is conduction filaments formation and rupture inside materials, the other is the interfaces-type resistive switching because of the barrier or junction between oxide layers and metal electrodes. Many perovskite rare earth nickelates (RENiO3) exhibit a sharp metal-insulator transition when temperature decreases. This thermally driven transition can be explained by charge disproportionation between two adjacent NiO6 octahedrons. Electron doping can also induce such a metal-insulator transition by reducing Ni3+ into Ni2+. We found SmNiO3 and NdNiO3 showed an enormous resistance increase at room temperature after hydrogenation due to electron doping and valency change. It has been proved that the resistance of H-NdNiO3 is able to switch under certain electrical operations, with controllable resistance states as wells as low energy cost. Date: Monday, July 8, 2019 Time: 1:30 PM Place: ARMS 1028