Abstract：The gallium melting point is an important defining fixed point in the International Temperature Scale of 1990 (ITS90) and plays a crucial role in temperature measurements near room temperature. When the phase transition of the high-purity gallium from the liquid state to the solid state happens, the volume expansion is about 3.1%.It can result in the rupture of the conventional glass container of the gallium point cells during the freezing process. In order to solve this problem, a special structure gallium melting point cell was successfully developed. At the same time, the gallium melting point is realized using different realization methods and devices. In addition, a comparative study was conducted between with a foreign similar product and the developed cell. The experimental results show that the temperature difference of the temperatures of the gallium melting point is consistentwithin of 0.02 mK, which is attributed to the trace impurities in high-purity gallium samples.. The temperature of gallium melting point realized with the outer liquid-solid interface method is 0.09 mK lower than that of the temperature obtained by the two-liquid-solid interface method. Effects of the realization apparatus on the gallium melting plateaus are small.
2020, Vol. 41 
