BaTiO3–Epoxy–ZnO-Based Multifunctional Composites: Variation in Electron Transport Properties due to the Interaction of ZnO Nanoparticles with the Composite Microstructure

Piezoelectric and electroactive composites are being investigated as a generation of self-powered energy harvesting devices for a wide range of applications. More specifically, three-phase piezoelectric composites are capable of maintaining high reliability, durability, and sensitivity, all while being economically feasible and nontoxic. In addition, three-phase composites can be tailored towards multifunctional applications depending on which material is incorporated as the third phase. The criteria that govern the applicability of these composites depend upon their electromechanical properties such as their impedance, resistivity, conductivity, and dielectric constant. Therefore, the present work involved fabrication of barium titanate–epoxy–zinc oxide (BT–Ep–ZnO) multifunctional composites, and study of the variation of their electron transport properties. The volume fraction of BT was held constant at 0.40, while the volume fraction of ZnO was varied from 0.01 to 0.10. The dipoles of the electroactive phases were aligned using a contactless corona plasma discharge poling technique. The impedance, resistance, conductance, and capacitance were measured over the frequency range from 20 Hz to 10 MHz. The geometry of the composites was measured and used to normalize the data by calculating the resistivity, conductivity, and dielectric constant. The piezoelectric strain coefficients, d33 and d31, were measured using a piezometer at frequency of 110 Hz. The fractured surface morphology and distribution of the particles were observed by scanning electron microscopy.