Introduction (1) S.J.T.U. Phase Transformation and Applications Page 5/42 Surfaces and Interfaces Everything is made of something and has to end somewhere. An atom at a free surface of a solid has greater energy than an atom in the interior of a crystal because it is less tightly bound. Surface energy The sum of all the excess energies of the surface atoms Can be defined in terms of energy,enthalpy, Helmholtz free energy,or Gibbs free energy, depending on the physical constraints placed on (a)由劈开晶体形成的自由键 the definition 本来应该担任配角”的界面比本当是主角”的构成相扮演更 重要的演出角色”！ SJTU Thermodynamics of Materials Spring 2008 X.J.Jin Lecture 20 surfacePhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2008 © X. J. Jin Lecture 20 surface Page 5/42 Introduction (1) Surfaces and Interfaces Everything is made of something and has to end somewhere. An atom at a free surface of a solid has greater energy than an atom in the interior of a crystal because it is less tightly bound. Surface energy The sum of all the excess energies of the surface atoms Can be defined in terms of energy, enthalpy, Helmholtz free energy, or Gibbs free energy, depending on the physical constraints placed on the definition 本来应该担任“配角”的界面比本当是“主角”的构成相扮演更 重要的“演出角色”！