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Impurity-Induced Structural Transformation of a MgO Grain Boundary

1998; American Physical Society; Volume: 81; Issue: 17 Linguagem: Inglês

10.1103/physrevlett.81.3675

1092-0145

Yongda Yan, Matthew F. Chisholm, Gerd Duscher, Amitesh Maiti, S. J. Pennycook, S. T. Pantelides,

High-pressure geophysics and materials

A combination of atomic-resolution $Z$-contrast imaging and first-principles density-functional calculations are used to establish that Ca impurities segregating to particular atomic columns in MgO grain boundaries induce a structural transformation. The presence of Ca in the boundary structure is independently confirmed by electron energy loss spectroscopy. The calculated electronic structure indicates that stabilization of the new boundary structure by Ca is a mechanical rather than an electronic effect.