The Effect of Argon Content on the β–γ Transition of Oxygen

As part of a larger project regarding the determination of argon content in oxygen based on measurements of the α–β solid–solid transition temperature of oxygen at 23.8 K, also the effect of argon on the β–γ solid–solid transition temperature at 43.8 K was measured. This transition being the main item of interest of these studies (correction of the O2 triple point temperature for argon content), the results obtained on the β–γ transition for two argon-in-oxygen mixtures (1002.29·10−6 and 351.14·10−6 mol·Ar·per·mol·O2) are presented here. A preliminary result from the first mixture, already included in a former publication, is combined with the present results for both mixtures to obtain an accurate value for the sensitivity of the temperature of the β–γ transition to argon content, along with a discussion regarding the effect of argon on the shape of the O2 transitions.