△G,=△H-TAs≈△U+P△-7(△S,+△Sm) △S Entropy of mixing △U Energy of formation of vacancy N! △S=klno=klnC inkIn n! (N-n) =-NH[C,nC1+(1-C,)n(1-C,) △G,=CN△U+M[C,lnC,+(1-C,)n(1-C,P ( ) v v m G  H TS  U  V T S  S Sm —— Entropy of mixing [ ln (1 )ln(1 )] !( )! ! ln ln ln v v v v n m N Nk C C C C n N n N S k k C k              [ ln (1 )ln(1 )] v v TN Cv Cv Cv Cv G  C NU  k    U —— Energy of formation of vacancy