This study reports on the electrical properties of organic/inorganic nanocomposites (PF/ZrO2) based on pyrogallol-formaldehyde aerogel, enriched by ultra-small zirconium oxide (ZrO2) nano-powder. After fabrication, the electrical conductivity of these nanocomposites can be fine-tuned over a broad range of conductivity levels. The programming of the electrical conductivity is achieved by applying high power current pulses. Once the desired electrical conductivity is tuned, the carbon nanocomposites-based devices exhibit a richness of nonlinear electrical phenomena, including an S-shape negative differential resistance and long-lived (up to 8 hours) transients in the electrical conductivity. The electrical metastable states are induced by the application of low power current pulses. This slow transient phenomenon and the non-linear electrical properties were explored in neuromorphic-like devices. Other types of circuit applications including oscillators and threshold switches, are also briefly presented, and discussed. Equivalented circuits are used to describe and simulate the basic electrical behavior.
Although, the non-volatile programming of the electrical conductivity, is well described by an electrothermal effect and joule heating, the physical mechanism behind long-lived conductivity relaxations is not yet elucidated. To gain insight into the physics of these slow relaxations a systematic study of the AC and DC electrical properties as function of temperature is presented and discussed.