Electrical conductivity of ceria nanoparticles under high pressure

This paper describes the electrical conductivity of ceria nanoparticles under high pressure ranging from 2 to 6 GPa. The samples used were pure and acceptor-doped ceria nanoparticles with a grain size of approximately 2 nm prepared by mixing hexamethylenetramine and metal nitrate solutions. The size of ceria nanoparticles was controlled to be 2 to 15 nm by varying heat-treatment conditions. The in-situ electrical conductivity measurements under high pressure were conducted by using an ac-impedance spectroscopy. By applying a pressure of 6 GPa at 300 °C, the green compact of 6 mol % Sm-doped ceria nanoparticles was densified; a relative density of 93% was achieved. The sample showed an electrical conductivity of 3 × 10 − 3 S/cm at 300 °C under 6 GPa. The enhancement of electrical conductivity under high pressure seems to be related to ionic conduction in the vicinity of grain boundaries.