Point Defect Structure of Chromium (III) Oxide

Raman spectra of p-type transparent semiconducting Cr2O3:Mg

“…Once the target composition, growth and post-annealing conditions have been optimised to maximise the oxygen partial pressure, the formation of MgCr 2 O 4 clusters in the thin films is suppressed, either due to an increased formation energy of MgCr 2 O 4 , or the decrease in formation energy for the active doping defect, most likely Mg Cr . These findings are very similar to early reports on the solubility of MgO in Cr 2 O 3 in solid solutions formed at high temperatures, where an increase in oxygen pressure was found to increase solubility [16].…”

Oxidation of Ni-Cr alloy at intermediate oxygen pressures. I. Diffusion mechanisms through the oxide layer

“…Fig. 8 represents the Brouwer diagram of Cr2O3 at 1100 °C according to Su and Simkovich [43]. It can be seen that when the external oxygen pressure is inferior to about 10 -10 atm, the main cationic defects throughout the whole scale thickness are chromium interstitials.…”

“…These gradients are mainly impacted by the defect concentration at the alloy/oxide interface and at the oxide/atmosphere interface respectively. According to the Cr2O3 Brouwer diagrams [43], the following features can be expected: (i) for a fixed external oxygen pressure, the vacancies concentration at the oxide/atmosphere interface gradually exceeds the interstitials concentration at the alloy/oxide interface with increasing temperature; (ii) an increase of the external oxygen pressure results in an increase of the vacancies concentration; (iii) a decrease of the chromium activity results in a higher oxygen pressure at the alloy/oxide interface (Eq. 1) and therefore results in a lower interstitials concentration.…”

“…A few data are available in literature on the defects concentration in Cr2O3: Su and Simkovich have determined via conductivity measurement a defects concentration around 10 18 at cm -3 at 1100 °C [43]. Vaari has estimated, from molecular dynamics simulations, defects concentrations varying from 10 3 up to 10 15 at cm -3 depending on the formation energy that had been used for computing [72].…”

Characterization of oxidation mechanisms in a family of polycrystalline chromia-forming nickel-base superalloys

“…atm) [52], where the main charge carriers are electron holes and chromium vacancies. One of the more frequently cited mechanisms for creating chromium vacancies was originally proposed by Callister et al [53] by way of a high-valence cation doping mechanism.…”