Abstract
A sealed glass cell was developed for the precise realization of the triple point of gallium.
The triple point of gallium, one of the most important fixed points for platinum resistance thermometry at room temperatures, has been realized by plastic cells. It is because of the increase in volume of gallium on solidification, and the plastic cell is not suitable for a leakage-free triple-point cell. Those problems are solved by adopting a vacuum glass cell with a teflon container.
The triple-point temperatures of gallium realized by the developed cell are found to be constant for about two months within ±0.04mK. The average temperatures measured by two standard platinum resistance thermometers are 29.77367°C and 29.77361°C by the representation of the International Practical Temperature Scale of 1968. The differences of the triple-point temperatures between the present sealed glass cell and the conventional plastic cell are also discussed.
