Biphase ordering o(111)

Scanning tunneling microscopy and low-energy electron diffraction have been used to study the effect of reduction on (Formula presented)(Formula presented)(111). The results show that the selvedge can exist as a superlattice of coexisting (Formula presented)(Formula presented)(111) and (Formula presented)O(111) islands, offering another example of the recently discovered phenomenon of biphase ordering. Two different structures that are able to coexist with this superlattice and increase in concentration as the surface is oxidized have been identified as resulting from a 'simple' termination of the (Formula presented)(Formula presented)(111) lattice. A more reduced selvedge is identified with islands of (Formula presented)O(111).