Conductivity and Ferroelectric Hysteresis in Bi4Ti3O12 Single Crystals Around Room Temperature

The dielectric response in Bi4Ti3O12 single crystals was studied at subswitching conditions at relative low temperatures (20-250 degrees C) and frequencies (100 mHz to 10kHz) both in-plane and out-of-plane. Electron-holes are likely to be the major charge carriers in both orientations although oxygen vacancies contribute as well. This scenario is supported by ferroelectric hysteresis loop measurements in both directions, showing aging in the c-axis direction but not in the a-direction. The absorption of blue laser light (3eV) above approximately 150 degrees C confirmed the main role of electron-hole carriers in conductivity at low temperatures.