Electric field dependent dielectric response of alumina/silicone oil colloids

We investigate the dielectric response of a mixture of alumina nanopowder and silicone oil. Frequency and electric field dependent measurements of another insulating colloid, i.e., urea-coated Ba$_{\mathrm{0.8}}$Rb$_{\mathrm{0.4}}$TiO(C$_{\mathrm{2}}$O$_{\mathrm{4}})_{\mathrm{2}}$ nanoparticles immersed in silicone oil, revealed universal dielectric response (UDR) characteristics and, with the application of high voltage, a negative capacitance. Alumina in silicone oil represents a simpler system in which to perform similar dielectric investigation. This colloid is sandwiched in a parallel plate capacitor cell, and the complex impedance is measured via lock-in amplifier at various frequencies and applied dc biases. Furthermore, we will compare and discuss the dielectric behaviors of different sized suspended alumina particles.