Iron oxide surfaces

I believe that in the Fe3O4(100) surface, we have developed a prototypical system to study this class of metal oxide compounds

Gareth S. Parkinson

2016

Scholarcy highlights

  • 1.1 MotivationIron and oxygen are two of the four most common elements in the Earth’s crust, and iron oxides form naturally through the weathering of Fe-containing rocks both on land and in the oceans
  • At room temperature the conductivity is similar to the poor metals, which is more than sufficient for surface science studies using the usual electron spectroscopies and scanning tunneling microscopy, and partly underlies the use of Fe3O4 as a prototype compound for the spinel class
  • TheR45° reconstruction observed in ultra-high vacuum experiments has subsequently been shown to be based on a non-stoichiometric reconstruction unrelated to the Verwey transition, a bulk termination, if it could be stabilized by cleaving a sample in UHV for example, could provide an interesting avenue to study charge and orbital ordering with high-resolution surface science methods
  • All other O atoms in the surface region are O2-. If we take these calculated oxidation states for the atoms we find that the outermost unit cell possesses a net charge of -3 electrons, exactly what is required to compensate the polarity in the direction
  • Since the OH groups and Antiphase Domain Boundaries are discussed in detail in their own right in sections 3.2.5.1 and 3.2.5.4, here we focus on defects 1-4
  • We find that Sn adsorbs in the “not blocked” site of the subsurface cation vacancy reconstruction as Sn1 adatoms, somewhat unsurprisingly given the experience with other metals
  • Changes to the physical and electronic structure near cation defects in Fe3O4 have been calculated using a DFT+U approach

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