Lanthanum-based perovskite's properties suit ceramic capacitors

Fabricating these products is difficult because the physical properties of the oxides and metals are very different. To achieve a high quality product, the manufacturing process needs to account for differences in synthesis temperatures and atmospheres, and for differences in expansion and shrinkage. A fabrication process that is optimised for the conducting metal electrodes can suppress the performance of the base oxides.

In a review paper published in the journal Science and Technology of Advanced Materials, a group of scientists in Japan investigated the potential of replacing metal electrodes in ceramic-based electronics with conductive oxides. Doing so could allow for more innovations in the ceramics industry. Oxide electrodes in these ceramic-based products would need to be highly conductive (above 10,000S/m) and stable in air at temperatures ranging between room temperature and 1173K (almost 900°C).

The team of researchers, from NGK Spark Plug Company and Nagoya University, fabricated oxides that have the potential to replace metal electrodes and investigated their physical properties above room temperature. Lanthanum-based perovskite-type oxides were chosen as having a potential for industrial use because they do not contain expensive rare metals, they are not environmentally hazardous, and they are stable in air up to 1173K.

Based on their investigations, the team found that the lanthanum-based perovskite-type oxide LaCo_0.5Ni_0.5O₃ showed high electronic conduction at high temperatures in air and was suitable for the fabrication of oxide electrodes and wiring in ceramic-based products.