Thermal Behavior of Stacking Faults in Graphite Platelets

Stacking faults were observed in graphite platelets by transmission electron microscopy over the temperature range 170° to 890°K. From measurements of fault widths w at various temperatures T, it was found that $${\text{(1/w)(∂w/∂T)=+(2.6±5.2)×10}}^{\text{−4}}{(}^{\circ }\mathrm{K}{)}^{\text{−1}}.$$ This value was used to obtain the estimate $${\mathrm{(Kb}}_p{\mathrm{/\gamma )(\partial /\partial T)(\gamma /Kb}}_p{\text{)=−(2.6±5.2)×10}}^{\text{−4}}{(}^{\circ }\mathrm{K}{)}^{\text{−1}},$$ where γ is the stacking fault energy, K the elastic coefficient of the fault, and b_p the magnitude of the partial Burgers vector. The essential temperature dependence of γ in graphite is of the same order as that of K, that is, (1/γ) (∂γ/∂T)∼(1/K) (∂K/∂T).