Probing on phase dependent luminescent properties of Al2O3 nanowires for their performance in ferroelectric liquid crystal

Herein, we have investigated the various characteristics of two structurally different phases of Al2O3 nanowires: (i) gamma-Al2O3 (cubic) and (ii) gamma-Al2O3 (monoclinic). These nanowires were synthesized via hydrothermal treatment followed by calcination. The structural and luminescent properties were analyzed by scanning electron microscopy, high-resolution transmission electron microscopy and time-resolved photoluminescence spectroscopy. A plausible formation mechanism was proposed on the basis of experimental observations and analysis. These nanowires of both phases exhibit blue emission at similar to 466 nm (2.65 eV) upon 253 nm UV excitation wavelength. The time-resolved photoluminescence spectroscopy indicated that the decay time (tau) of theta-Al2O3 nanowires (tau = 273 picoseconds) is longer than that of gamma-Al2O3 nanowires (tau = 198 picoseconds). Moreover, these Al2O3 nanowires were dispersed in ferroelectric liquid crystal (FLC) to observe their effect on the electrooptical characteristics. The electro-optical response of the composite devices showed faster electrooptical response, thereby suggesting potential applications in electro-optical shutters and modulators.