 
Summary: Journal of Nuclear Materials 126 (1984) 8385
NorthHolland, Amsterdam
83
LETTER TO THE EDITORS
INTERNAL PRESSURE APPROACH FOR THE ESTIMATION OF CRITICAL
TEMPERATURES OF Li(l), K(I) AND NaK(f)
1. Introduction
An internal pressure approach was developed by
Srinivasan and Ganesan [I] for the estimation of the
critical temperature of Na(l) based on an equation of
state originally derived by Suryanarayana [2] using a
few basic thermodynamic relationships. The equation of
state derived by Suryanarayana can be represented as
follows:
(Pt Pi)= TC2a(pCp/(Cp+ TC2a2). (1)
where p is the density (kg me3), C the ultrasonic
velocity (m sl), Cr, the specific heat at constant pres
sure (J K`/kg) and fy the volume expansivity (Kl).
It was shown [1,3] that a plot of (P + Pi)/Tversus T
is almost linear for many substances and could be fitted
