Preparation and structural evolution of Mo/SiOx protective coating on CoSb3-based filled skutterudite thermoelectric material

Abstract A Mo/SiO x multilayer film was deposited on a Ce 0.9 Fe 3 CoSb 12 skutterudite surface as a protective coating by magnetron sputtering. A thermal aging test was conducted under vacuum at 823–923 K, and the microstructural evolution of the multilayer film and the effects of the protective coating on the suppression of Sb sublimation were investigated. The as-prepared Mo layer is crystallized in a body-centered cubic structure with preferred orientation of the (1 1 0) plane parallel to the substrate, whereas the SiO x layer is amorphous. The formation of a Mo 3 Sb 7 interlayer between the skutterudite and coating was observed after the high temperature thermal aging that enhanced the adhesion between the coating and the skutterudite. The Mo 3 Sb 7 layer is chemically stable at high temperatures; therefore, it blocks the further diffusion of Mo and Sb on the boundary. The Mo 3 Sb 7 /Mo/SiO x multilayer coating can effectively suppress Sb sublimation, enabling high temperature applications of the CoSb 3 -based thermoelectric device.