Negative capacitance (NC) is a rather ubiquitous phenomenon that is found in many complex materials ranging from semiconductor devices to biological membranes. The underlying physical processes in this diverse collection differ considerably. However, we previously demonstrated that a relationship exists between NC and the conductivity of the material. Here, we examine and exploit this relationship in an effort to pinpoint the source of NC in a nanocolloid, composed of urea coated nanoparticles in silicone oil, which has previously been shown to exhibit the NC effect. This is accomplished by investigating the influence of several external parameters, such as temperature and moisture content, on the NC and conductance of the colloid as well as solid materials created from the nanoparticles used in the colloid. In addition to NC, the colloid demonstrates the electrorheological (ER) effect. It is shown that large scale particle motions, such as those that generate the ER effect, are not responsible for the NC. The results demonstrate that the nanoparticle surface conductivity is the relevant parameter to the NC in this system, effectively isolating the origin of the NC to nanoparticle surface. Further, this appears to be a rather general feature of NC in dielectric nanosystems.
All Science Journal Classification (ASJC) codes
- General Physics and Astronomy