3.1 Diffusion

• Diffusion causes changes in the microstructures to take place in processes such as sintering, creep deformation, grain growth etc.

• Diffusion is also related to transport of defects or electronic charge carriers giving rise to electrical conduction in ceramics. Ionic conductors are used in variety of applications such as chemical and gas sensors, solid electrolytes and fuel cell. For example, an oxygen sensor made of ceramic ZrO₂ is used in automobiles to optimize the fuel/air ratio in the engines.

• Atomic diffusion rates and electrical conductivity are largely governed by defect types and their concentration where concentration is a function of temperature, partial pressure of oxygen or pO_2, and composition.