Surface phase transitions and related surface defect structures upon reduction of epitaxial WO3(100) thin films: A scanning tunneling microscopy study

摘要: The evolution of surface morphology and reconstructions induced by reducing epitaxial WO3(100) thin films on LaAlO3(100) were studied using scanning tunneling microscopy (STM). As the reduced transformed from p(2×2) to p(5×2) p(4×2) p(3×2) finally (1×1); at intermediate stages mixtures phases observed. structure changed became progressively darker indicating a connection between bulk reduction. formation structures could be explained ordering vacancies created W5+ migration into troughs. ordered troughs gave stranded appearance in STM images. was narrowed create surface; reduction this way (1×1) with all W ions 5+. Half-height steps due crystallographic shear planes intersecting characterized surface. Several defect characteristic p(n×2) surfaces including domain boundaries oriented parallel strands along [011], in-plane line defects across strands, wide crosslinks above strands. Structural models for these are proposed based results. [011] attributed stress domains reconstructed uniaxial