Transition from Order to Configurational Disorder for Surface Reconstructions on SrTiO 3 (111)

摘要: There is growing interest in ternary oxide surfaces due to their role areas ranging from substrates for low power electronics heterogeneous catalysis. Descriptions of these date focus on low-temperature explanations where enthalpy dominates, and less the implications configurational entropy at high temperatures. We report here structure three members n×n  (2≤n≤4) reconstructions strontium titanate (111) surface using a combination transmission electron diffraction, density functional theory modeling, scanning tunneling microscopy. The contain mixture tetrahedral TiO_{4} units found (110) sitting top octahedral TiO_{5}[] (where [] vacant site), TiO_{6} second layer that are similar those (001) surface. find clear evidence transition ordered enthalpy-dominated 3×3 4×4 structures entropy-dominated 2×2 formed higher This changes many aspects how should be considered, with significant growth.