This preview shows pages 1–2. Sign up to view the full content.
Classification of Phase Transitions
:
Ehrenfest’s Scheme
Note that when we derived ClausiusClapeyron Eq. we moved along the coexistence curve and for each
point we have used
12
But we have not put any restrictions on
or
GG
PT
;
TP
VS
PP
―normal derivatives‖ of G
If these derivates are discontinuous –
First Order
Phase Transition
If these derivates are continuous, but the higher order derivates are
discontinuous
–
nth order
transition.
Unfortunately, Nature has not cooperated with Ehrenfest’s scheme except for the important case of First
Order Phase Transition.
For example, Sp. Heat → 2
nd
derivative
Diverges
at the critical point of a magnetic phase transition
Modern Usage –
1
st
order and Continuous Phase Transition
Unambiguous Definition of Phase Transition
In
single phase regions
of the
PT
plane,
G (T, P)
is an analytic function bounded by coexistence curves
along which the function is not analytic.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '10
 Chakabarti
 mechanics, Statistical Mechanics

Click to edit the document details