Equilibrium melting curves of relatively pure and doped silver samples

Abstract

Six silver samples were doped with Pd, Fe, Au, In, Sn, Pb, Zn, Sb, Cu, Ni and Al. The resulting shifts in the equilibrium melting curves were then determined. All impurities caused a shift in the liquidus point of silver except aluminium, for which no conclusive results could be obtained. The shifts, in millikelvins, caused by one part per million by weight of each of the above impurities (with the exception of the last mentioned, Al), were determined to be +0.97, +0.13, +0.09, −0.49, −0.60, −0.48, −1.10, −0.73, −0.69, and −0.74, respectively. Four of the initial samples were recently acquired and of 99.9999 % purity. Their melting points were realized within a scatter band of ±0.55 mK. Using the above measured shifts and the amount of impurities detected in these samples by glow discharge mass spectrometry (GDMS), it is estimated that the liquidus points of these samples differ from that of ideally pure silver by no more than 1.0 mK within an expanded experimental standard deviation of the mean of 0.2 mK, using a coverage factor of 2.