Nanomechanical properties and fracture behaviors of Ba_1-xK_xCe_0.6Zr_0.2Y_0.2O_3-δ electrolytes by nanoindentation

The nanomechanical characteristics and fracture behaviors of the Ba_1-xK_xCe_0.6Zr_0.2Y_0.2O_3-δ (K-doped BCZY, 0.0 ≤ x ≤ 0.15) oxides were investigated by using nanoindentation techniques. The BKCZY samples were prepared by the citrate-ethylenediaminetetraacetic acid (EDTA) complexing sol-gel process, followed by uniaxial pressure pressing and sintering at 1600 °C for 4 h. The XRD results indicated that the BKCZY samples occurred predominantly in perovskite-type cubic structures. The hardness and Young's modulus of BKCZY samples were measured by a Berkovich nanoindenter operated in continuous contact stiffness measurements (CSM) mode. Results indicated that the hardness and Young's modulus of BKCZY sample decreased substantially with increasing the K doping concentration, presumably due to doping-enhanced grain growth. Furthermore, the SEM observations indicated that Berkovich nanoindentation-induced fracture mode was mostly transgranular and the fracture toughness exhibited a similar doping dependence as that of the hardness and Young's modulus.