Effect of Fillers on Electromechanical Properties of Composites for Potential Sensing Applications

Among dielectrics, electrostrictive materials possess good electromechanical properties and are preferred in many applications, including tactile sensing. These properties can be further enhanced by addition of filler particles of materials like Al₂O₃, SiO₂, TiO₂, ZnO, and so forth. Improved properties of such composite materials result in enhancement of sensor´s response. The objective of this paper is to analyze and compare the improvement in properties of these composite dielectric materials. Graphs have been plotted for values of tan delta and relative real permittivity with respect to variation of TiO₂ and ZnO filler particle concentration. It is found that in nanocomposite with ZnO filler particles, reduction in losses is more as compared with TiO₂ filled nanocomposite, whereas TiO₂ is a better filler material in comparison to ZnO for increasing permittivity of the nanocomposite. Further study has been done in respect of increase in interfacial volume fraction for various sizes and concentrations of filler particles. It is observed that when filler particle size is reduced from 5 to 0.5 nm, interfacial volume fraction increases by 900%. Another aspect studied is variation in Young´s modulus on increasing volume percentage of microfillers for four different sizes in range (0.15-0.92 μm). For all sizes of microfillers, Young´s modulus initially increases indicating enhancement in mechanical strength or toughness of composite, but later on, it starts decreasing. It is also observed that there is diverse opinion among researchers on the electromechanical properties of the composite and analysis has been made on the possible reasons for such diverse opinion.