Ab initio atomistic thermodynamical study of oxygen desorption and nitrogen adsorption on [Formula omitted] surfaces

Five surfaces with low Miller indices, including (001), (011), (111), (01 [Formula omitted]) and (11 [Formula omitted]), were generated by cleaving rhombohedral [Formula omitted], and their surface energies were compared, which showed that (011) is cleaved more easily than others, followed by (001),...

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Bibliographic Details
Published in:Journal of materials science 2019-04, Vol.54 (7), p.5561-5569
Main Authors: Ri, Mun-Hyok, Ri, Un-Son, Kim, Kyong-Il, Sin, Yun-Sop
Format: Article
Language:English
Subjects:
Adsorption
Comparative analysis
Energy (Physics)
Evaporation
Materials science
Nitrogen
Oxygen
Phase diagrams
Substitutes
Surface science
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Summary:Five surfaces with low Miller indices, including (001), (011), (111), (01 [Formula omitted]) and (11 [Formula omitted]), were generated by cleaving rhombohedral [Formula omitted], and their surface energies were compared, which showed that (011) is cleaved more easily than others, followed by (001), (111), (01 [Formula omitted]) and (11 [Formula omitted]), so that we focused on (011), (001) and (111) surfaces. Phase diagram of stoichiometric, oxygen-deficient and nitrogen-substituted [Formula omitted] (001) surfaces indicated that oxygen evaporation does not take place on stoichiometric surface, and oxygen-to-nitrogen substitution is not a indirect (two-step) process (oxygen evaporation, followed by nitrogen substitution into oxygen vacancies). It was proved from minimum energy path (MEP) and DFT total energy curves over MEP that the energy barrier of direct oxygen-to-nitrogen substitution process is lower than indirect process, and therefore, direct process is easier to take place than indirect process.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-018-03252-3