The test of the validity of the Fromhold-Cook theory of metal oxidation for the O2/Fe system in the tunnel regime is impeded by the growth of a passivating Fe2+/Fe3+ double layer at T=150 degrees C. However, during an intermediate anneal step at 200 degrees C, the Fe3+ is reduced to Fe2+. The oxidation rate of this annealed layer is in agreement with the Fromhold-Cook theory. At room temperature, the ionic current is rate limiting. For T>150 degrees C, the thermionic emission of electrons is rate limiting for oxygen coverages larger than 13x10(15) atoms/cm(2).
Mixtures of liquid‐crystalline di‐oxetanes and mono‐oxetanes are made for the purpose of making birefringent films by photopolymerization. The composition of a di‐oxetane mixture that forms spin‐coated films of planarly aligned nematic monomers is reported. These films are photopolymerized in air. The molecular order of the monomers can be changed on the microscale to form thin films with alternating birefringent and isotropic parts by using a combination of photopolymerization and heating. The interface observed between the birefringent and isotropic 10 μm × 10 μm domains is very sharp and the films show hardly any surface corrugation. In addition, the polymerized films are thermally stable, making them very suitable for use as patterned thin‐film retarders in high‐performance transflective liquid‐crystal displays (LCDs) which satisfy customer demand for displays that are brighter and thinner and that deliver better optical performance than conventional LCDs with an external non‐patterned retarder.
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