Atomic dynamics in europium and iron oxide nanoclusters

The atomic mobility in europium and iron oxide nanoclusters entrapped in ac tivated carbon matrices was studied, The temperature dependences of the Eu- 151 and Fe-57 Mossbauer effect probabilities were determined for nanosystem 1 with Eu2O3 clusters in activated carbon and nanosystem 2 with Eu2O3 and Fe2O3 nanoclusters in activated carbon. In nanosystem 2, a fusion-type phas e transition was observed at T similar to 200K. The results were interprete d in terms of the model according to which atomic mobility increases (nanos ystem 1, Eu2O3, and nanosystem 2, Fe2O3) as the Debye temperature decreases to Theta (D) = 290-300 K because of surface effects and the fusion-type fl uctuation transition for EU2O3 nanoclusters in nanosystem 2 with an R-cr < 2 nm critical radius.