Microhardness and fracture toughness of ZrO2–Sc2O3 solid electrolyte, doped with rare-earth and transition metals

Abstract

The influence of low concentrations (1 mol %) of co-dopants (Y, Ce, Gd, Er, La, Zn, Mn, Co and Cu) on the microhardness and fracture toughness of Zr_0.81Sc_0.19O_2–δ (10.5ScSZ) solid electrolyte was studied by the indentation method. It was shown that co-doping of 10.5ScSZ by the rare-earth elements (Y, Ce, Gd, Er) results in microhardness increase on 4–45% due to stabilization of cubic phase in the grains, while the microhardness changing upon transition metals (Mn, Cu, Co, Zn) introduction is caused by the grain boundaries modification. The microhardness decreases on ~4 and 10% upon doping by Mn and Cu, accordingly, whereas the introduction of Co and Zn results in its increase approximately by 2 times. It was shown also that the influence of all investigated dopants on the fracture toughness is insignificant. The maximal effect observed for Cu was the fracture toughness increase from 2.1 up to 2.6 MPa m^0.5.