Study on the realization of indium point

Indium-point cells were fabricated in NMIJ/AIST using high grade indium samples purchased from some different metal sources. The quality of the indium-point cells were evaluated by conducting temperature measurements during the solid-liquid equilibrium condition, under which the indium fixed-point is defined. Comparisons of fixed-point temperature realized within the cells including the conventional and the newly developed ones were also conducted. The results of these comparisons, termed as direct cell comparisons, as well as the above mentioned temperature measurements under the solid-liquid equilibrium were used to evaluate the effect of impurities to the realization of the indium point. The present paper outlined the cell fabrication, the temperature measurements and the evaluation of impurity effect to the indium point realization.