Resistive‐switching in yttria‐stabilised hafnia ceramics

Yttria-stabilized hafnia ceramics are high-temperature oxide ion conductors that lose a small amount of oxygen, both at high temperatures and on the application of a small dc bias. At zero applied bias, a small amount of p-type conductivity is present. This increases with low bias and is attributed to reactions initiated at the positive electrode/ceramic interface. With a further increase in bias, n-type conductivity is initiated at the negative electrode/ceramic interface. After a short time-lapse, the overall conductivity increases rapidly by 1.5–3 orders of magnitude and is reversible, with hysteresis, on subsequent removal of the bias. Switching has been observed over the range 457–531°C and is sensitive to both temperature and oxygen partial pressure in the surrounding atmosphere. This is the first example of low field, resistive switching in bulk hafnia ceramics, in contrast to most examples of resistive switching which are observed in nanometre-thick devices using similarly applied voltages.