3. Identification of physical phenomena

3.1 Ion/electronic conduction

Ion conduction is based on a jump transport mechanism assisted by temperature and electric field. Ions can be intrinsic to the network, as in the case of ionic solids. They can also be extrinsic, due to impurities in purely covalent networks, as in the case of many polymers. Ions may, for example, arise from the manufacturing process, exposure to radiation, thermal degradation or even water absorption (thus forming OH ^– and H ⁺ ions). As temperature rises, ion mobility increases. This generally leads to an Arrhenius law (equation (12) ) (figure