Electrical Conduction in Dense Polycrystalline Rutile at Low frequencies

The complex ionic-electronic conduction in rutile has been considered for the fabrication of memristive devices with different structures. The memristive features of the device is believed to originate from the motion of the ionized oxygen vacancies within the oxide crystal. Here, we investigate the conduction mechanism in Ti/poly-rutile/Ti devices at low frequencies, wherein the contribution of ionic movement to the charge conduction is significant. The I-V characteristics of the device are recorded by applying triangular voltages ranging from -2 to +2 V at different frequencies in the range of 0.01-100 Hz. Recorded results demonstrate very different I-V plots for voltage sweeping frequencies of 0.01 and 100 Hz. Even after applying compensations for the capacitive current, the device current at 0.01 Hz is significantly larger than that at 100 Hz. The obtained results are described by assuming conductive filament formation within the polycrystalline solid; these filaments provide easy conduction routes which changes the conduction status in the sample.