Influence of magnetic field on the AC conductivity and dielectric properties of Ni/silicone rubber composite

Nisilicone rubber composites were prepared with the metal (Ni) and silicone rubber (110) by a mass ratio of 2.7∶1 using a room-temperature twice cure method. At the room temperature, the sample’s piezoresistive and dielectric properties were measured before and after applying a 0.024 T magnetic field. The results show that when the uniaxial force increases from 3.75kPa to 312.5kPa, the sample’s resistivity decreases 8 orders of magnitude. Compared with the values measured before applying the magnetic field, the AC conductivity at low frequencies(40~104Hz) increases 2.46 times, the dielectric constant increases 20% and the dielectric loss increases 2 times by the action of a 0.024T magnetic field. This is mainly caused by the composite’s tunneling-magnetoresistance and magnetoelectric coupling effect. After taking away the magnetic field, conductivity, dielectric constant and dielectric loss could not go back to the initial values, which has something to do with the ferromagnetism of Ni powders. Ni-silicone rubber pressure-sensitive composites have potential applications in magnetic sensors and information storage with the properties of piezoresistive, TMR and magnetoelectric coupling effects.