科研之友
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摘要
Order-disorder transformation triggered by mechanical activation in a perovskite structure was observed in Pb(Sc1/2Ta1/2)O-3; it is simulated using a Monte Carlo algorithm, based on the competition between mechanical activation leading to disordering and the thermal diffusion recovering the ordering. The time evolution of the long-range order (LRO) from an initial ordered state shows a steady decrease at the initial stage and then becomes more or less stabilized over a prolonged period; while from the disordered initial state, LRO increases first and then stabilizes at a similar end value. Thermal diffusion is the dominant process at relatively high, temperatures, leading to the disorder-to-order transformation. The effect of mechanical activation becomes significant and results in order-to-disorder transformation at relatively low temperatures. Both the mechanical activation intensity and the vacancy migration energy exert an impact on the degree of ordering and the order-disorder transformation temperature at low temperatures. Snapshot images of the simulation demonstrate the competition between thermal diffusion and mechanical activation, which refines the domain size.
- 出版日期2002-9-23
- 单位南京大学
