Pressure dependence of the melting and ?-? phase transition temperatures of carbon monoxide

Abstract

The pressure dependences of the melting temperature T/sub m/ and crystallographic phase transition temperture T/sub b/of carbon monoxide have been measured as a function of hydrostatic pressure to 1.75 kbar by using associated changes in the nuclear spin-spin relaxation time T/sub 2/ of /sup 13/C as an indicator of the transitions. From the Clausius-Clapeyron equation the volume increments at zero pressure are deduced to be ..delta..V/sub m/=2.50 +- 0.07 and ..delta..V/sub alphabeta/cm/sup 3//mole. The CO phase diagram is compared with that of N/sub 2/.