The Self-Repairing Of Ion Irradiation Damaged Mo-S-Ti (Most) Lubricant Films By Thermal Annealing

Mo-S-Ti composite films deposited by magnetron sputtering were irradiated by 2 MeV Au2+ with a high fluence of 3.3 x 10(15) ion cm(-2). Upon intense bombardment by 2 MeV Au2+, the Mo-S-Ti thin film exhibits sensitivity to radiation-induced amorphization at room temperature. Afterwards, thermal annealing experiments on the irradiated thin films were conducted over the temperature range of 200 degrees C-900 degrees C. Subsequent annealing experiments found that the effect of heavy ion irradiation on Mo-S-Ti films was a reversible reaction, with the irradiation-damaged MoS2 lattice being completely self-repaired by thermal annealing. In the annealing temperature range of 200 degrees C-600 degrees C, no evidence of an amorphous to recrystallized transition was observed. When the temperature was increased to as high as 700 degrees C, the damaged MoS2 molecules were well recrystallized. HRTEM images of irradiated samples annealed at 700 degrees C strikingly found that the self-repaired MoS2 crystallites preserving long range ordering were still rearranged in an intrinsic (0 0 2) crystal orientation. MoS2 nanocrystals that survived the ion bombardment step may provide some nucleus for subsequent MoS2 grains growing dominantly in the (0 0 2) direction in thermal annealing. Compared with the difficult recrystallization in thermal annealing, the irradiation-amorphized MoS2 phases were easily self-repaired under friction. The low transition potential barrier from irradiation-induced amorphization to crystallization, achieved by mechanical working, may be an important reason for the quick recrystallization.