Development and precise determination of temperature fixed point based on n-tetradecane

Abstract In this study, a temperature fixed point based on n-tetradecane was developed. The determination results of the melting plateau were also reported. By repeatedly realizing the melting plateau of n-tetradecane, its duration was determined to exceed 100 h, with a reproducibility of 0.81 mK. The stability of the melting plateau was improved by applying overheating at the beginning of the melting process. During the stable plateau period, the temperature variation within 60 h is less than 3 mK, with a variation rate of approximately 0.08 mK h −1 . By using the point of inflection method, the melting temperature of n-tetradecane was determined to be 5.8643 °C, with an uncertainty of 0.0068 °C ( k = 2). This work determined the melting temperature of n-tetradecane with higher precision, the measurement uncertainty is lower than the values reported in previous studies. The phase transition properties of n-tetradecane demonstrate its potential to serve as a temperature fixed point.