PLASTICITY AT CRACK TIPS IN GD3GA5O12 GARNET SINGLE-CRYSTALS DEFORMED AT TEMPERATURES BELOW 950-DEGREES-C

Single crystals of Gd//3Ga//5O//1//2 have been strained under confining pressure (1. 5 GPa) at temperatures below 950 degree C. No evidence for macroscopic plasticity was found, but transmission electron microscopy revealed dislocation generation at crack tips. Deformation mechanisms are different from those operating in the high-temperature regime: extending stacking faults in left brace 110 right brace planes and the LT AN BR 010 RT AN BR left brace 100 right brace glide system were observed. Dissociations of a/4 LT AN BR 111 RT AN BR partial dislocations were also observed.