A calculation of the formation energies of intrinsic defects near grain boundaries in NiO

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Abstract
The formation energies of intrinsic defects near coincidence pin boundaries in NiO have been calculated using computer simulation techniques. At each type of interface ionic sites with defect formation energies lower than the corresponding bulk values were found. Therefore the equilibrium concentration of all defects will be enhanced clone to the boundary. However, the concentration of singly charged vacancies is enhanced more than the concentration of the compensating holes. Therefore a net negative charge density is produced in the boundary region. This is compensated by a positive apace-charge layer. For the example of e (211)/[011] interface at 1000 K, the calculations predict an increase in the vacancy concentration of about 40 over the bulk value in the boundary region. Thin will contribute towards an increased diffusion coefficient.