Extended BEG model of monhalogenated methanes physisorbed on ionic crystals

SURFACE SCIENCE

卷:554

Article

Burns, TE ; Dennison, JR ; Kite, J

关键词: surface thermodynamics (including phase transitions);    Ising models;    halides;    alkanes;    magnesium oxides;    alkali halides;    physical adsorption;   

DOI  :  10.1016/j.susc.2004.02.010

来源: Elsevier

【 摘 要 】

The 2D dielectric phases and phase transitions of adsorbed dipolar molecules are modeled using a dilute spin-one Ising model. This model is studied in the Blume-Emery-Griffiths formalism, using a mean-field approximation, where the interaction parameters are uniquely determined from the system interaction energies using an averaging procedure. The model is applied to four monhalogenated methane species physisorbed on MgO(1 0 0) and NaCl(1 0 0) surfaces using previous experimental and theoretical studies to estimate the interaction energy parameters. We find that temperature- and coverage-dependent antiferroelectric to ferroelectric, coverage-dependent ferroelectric up to ferroelectric down, reentrant ferroelectric to ferrielectric, and order-disorder dipole phase transitions can occur. Phase diagrams based on this model are presented. (C) 2004 Elsevier B.V. All rights reserved.

【 授权许可】

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