Combined study of internal nanovoids in Cu0.1Ni0.1Co1.6Mn1.2O4-based thick-film layers formed near grain boundaries

Abstract

Microstructural features of Cu0.1Ni0.8Co0.2Mn1.9O4-based thick films screen-printed on substrate with formed Ag–Pd contacts were investigated using X-ray diffraction, scanning electron microscopy methods. It is established that diffusion processes of elements from contacts area occurs into internal structure of thick films located near grain boundaries. Formed internal nanovoids in thick-film structures were studied by positron annihilation lifetime spectroscopy. The observed positron trapping sites can be defined within two-state positron trapping model at fitting on two components. It is established that positron trapping processes in thick films formed in three and four layers and bulk Cu0.1Ni0.8Co0.2Mn1.9O4 ceramics are similar testifies the same structural type and successful transformation of bulk ceramics into thick films. In some cases, the size of free-volume nanovoids in thick films can rise due to redistribute space of their internal structure at addition glasses and other compounds. Positrons are trapped more strongly in bulk ceramics due to more ramified their grain/pores structure. Studied thick films are characterized by high temperature sensitivity and their properties can be stabilized after thermally induced treatment.