Mechanical properties of LaFeO3 ceramics

The fracture strength, fracture toughness and apparent Young's modulus of LaFeO3 ceramics in the temperature region 25-800 °C are reported. The fracture strength of the material was observed to increase from 202 ± 18 MPa at room temperature to 235 ± 38 MPa at 800 °C. The room temperature fracture toughness was 2.5 ± 0.1 MPa m1/2. The fracture toughness decreased to 2.1 ± 0.1 MPa m1/2 at 600 °C, followed by an increase to 3.1 ± 0.3 MPa m1/2 at 800 °C. The temperature dependence of the fracture toughness correlates well with the crystallographic strain, |(a−c)|/(a+c), and ferroelastic toughening of LaFeO3 materials is inferred. Non-elastic stress-strain behaviour of the LaFeO3 materials due to ferroelasticity was confirmed by cyclic compression experiments, and residual strain was observed in the material after unloading.