The room temperature mechanical properties of a mixed conducting perovskite
Sm1-xSrxCo0.2Fe0.8O3 (x = 0.2 to 0.8) were examined. Density, crystal phas
e, and microstructure were characterized. It was found that the grain size
increased abruptly with increasing Sr content. Mechanical properties of ela
stic modulus, microhardness, indentation fracture toughness, and biaxial fl
exure strength were measured. Young's modulus of 180-193 GPa and shear modu
lus of 70-75 Cpa were determined. The biaxial flexure strength was found to
decrease with increasing Sr content from similar to 70 to similar to 20 MP
a. The drop in strength was due to the occurrence of extensive cracking. In
dentation toughness showed a similar trend to the strength in that it decre
ased with increasing Sr content from similar to 1.1 to similar to 0.7 MPa m
(1/2). In addition, fractography was used to characterize the fracture beha
vior in these materials.