Based on this stress value and the methodology established in Fincher et al, it is possible to determine the flaw size of a dendrite that can be deflected with the present stress. Equation 1 is adapted from Fincher et al to determine the flaw size a and assumes a KIC= 1 MPa m 1/2 for LLZO, same as in the reference, that our determined compressive stress at -700 MPa is 10 % higher than the critical stress σcrit to deflect all growing cracks to 90° giving a σcrit =636 MPa.