Tin-, titanium-, and magnesium-doped alpha-Cr2O3: characterisation and rationalisation of the structures

Ayub, Ibrar; Berry, Frank J.; Johnson, Clive; Johnson, David A.; Moore, Elaine A.; Ren, Xiaolin and Widatallah, Hisham M. (2002). Tin-, titanium-, and magnesium-doped alpha-Cr2O3: characterisation and rationalisation of the structures. Solid State Communications, 123(3-4) pp. 141–145.

DOI: https://doi.org/10.1016/S0038-1098(02)00213-2

Abstract

Tin- and titanium-doped α-Cr2O3 have been prepared by the calcination of precipitates. Rietveld structure refinement of the X-ray powder diffraction patterns shows that the dopant metals occupy interstitial sites and partially substitute on octahedral chromium sites in the corundum-related α-Cr2O3 structure. Interatomic potential calculations show that such defects are energetically more favourable than the exclusive substitution of chromium or the occupation by the dopant of interstitial sites in α-Cr2O3 with charge balance being achieved by an appropriate number of cation vacancies. However, the attempted incorporation of magnesium within α-Cr2O3 results in the formation of spinel-related MgCr2O4. The observation is rationalised in terms of the greater thermodynamic stability of the spinel-related structure.

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