Approximate Calculation of Solid Surface S.J.T.U. Energy (2) Phase Transformation and Applications Page 12/42 If we cleave a face-centered cubic crystal along a(111)plane,three bonds per atom will be broken.Two surfaces formed,the work required to form the surfaces will be 38/2 per surface atom. 3 △Hs W= (for Z=12) 2 ANA △H 4N4 A aov2 N/A is the number of atoms per unit (Face diagonal) area.For fcc structure: Figure 4.2 Atomic packing on the (111)face of a face-centered N 4 cubic crystal. A √3a 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 12/42 Approximate Calculation of Solid Surface Energy (2) If we cleave a face-centered cubic crystal along a (111) plane, three bonds per atom will be broken. Two surfaces formed, the work required to form the surfaces will be 3ε/2 per surface atom. )12( 423 = Δ == Zfor NH w AS ε N/A is the number of atoms per unit area. For fcc structure: ⎟⎠⎞ ⎜⎝ Δ ⎛ = AN NHAS 4 γ 2 3 0 4 A a N =