A method to measure fracture toughness using indentation in REBa2Cu3O7-δ superconductor single crystals

A method is proposed to estimate indentation fracture toughness based on the critical load for crack nucleation calculated by the derivative of the loading curve. This method is applied to REBa2Cu3O7-delta superconductor single crystals based on xenotime, where is difficult to observe well defined radial crack lengths due to its lamellar structure. The indentation fracture toughness agrees well with that obtained from the traditional method based on radial crack propagation. The proposed procedure is an alternative technique to estimate indentation fracture toughness without the necessity of measuring radial cracks lengths while keeping the advantages of the traditional method. (C) 2011 American Institute of Physics. [doi:10.1063/1.3662121]