Erbium hardness

Dysprosium - the atomic number is 66 and the chemical symbol is Dy. The name derives from the Greek dysprositos for hard to get at , due to the difficulty in separating this rare earth element from a holmium mineral in which it was found. Discovery was first claimed by the Swiss chemist Marc Delafontaine in the mineral samarskite in 1878 and he called it philippia. Philippia was subsequently found to be a mixture of terbium and erbium. Dysprosium was later discovered in a holmium sample by the French chemist Paul-Emile Lecoq de Boisbaudron in 1886, who was then credited with the discovery. It was first isolated by the French chemist George Urbain in 1906. 

In 1878, French chemist Jean-Charles-Galissard de Marignac reported his analysis of the mineral erbia. Erbia was one of the minerals found a century earlier in an interesting new rock called yttria. The rock had been discovered outside the town of Ytterby, Sweden, in 1787 by Swedish army officer Carl Axel Arrhenius (1757—1824). In the century that followed Arrhenius discovery, chemists worked hard to find out what elements were in yttria. Earlier chemists thought erbia was a new element, but Marignac disagreed. He said that erbia consisted of two new elements, which he called erbium and ytterbium. 

The metallurgical applications of erbium are few, as it slowly tarnishes in air, and it is attacked by water. However, it is added to alloys with metals such as vanadium, because it lowers their hardness. The alloys become more workable because of this (Emsley 2001). 

According to the systematic study by Ross (1967) of the effect of cold rolling on the hardness of yttrium and twelve of the lanthanide metals, the hardness of all metals except La, Nd, Er, Y, and perhaps Sm tends to increase rapidly during the initial 20-25 percent reduction. Further hardening does not occur until reductions of the order of 60 percent (see fig. 8.5). This is in agreement with the earlier work by Love (1960) on erbium and dysprosium shown in fig. 8.6. A comparison of the effect of 50 percent cold work by swaging (Love, 1959) or... 

Investigations of phase equilibria in the erbium-yttrium system have been conducted by Markova et al. (1964) and by Spedding et al. (1973). The first group used distilled yttrium metal of 99.6(wt )% purity and erbium metal of about 98(wt )% purity. The principal impurities included Ca, Fe, Cu, Ta and other rare earth metals. The alloys were arc-melted under purified helium and studied in the annealed state. Microscopy, differential thermal analyses and X-ray methods were utilized and measurements of hardness and electrical resistivity were performed on the alloy specimens. The main difficulty experienced in their thermal analysis was the narrow temperature interval between the melting of their alloys and the polymorphic transformations. 

The difference in activity among the lanthanide salts was further demonstrated by the fact that para-nitrobenzaldehyde was not acetalized after 20 hr in the presence of erbium chloride, but was completely converted when ytterbium chloride was the catalyst. This is consistent with the observation that acetalization yields increased with increasing atomic number (decreasing ionic radius), a phenomenon related to the Lewis acidity (or degree of hardness) of the cations. The role of the lanthanide catalyst is not well-defined, however. 

The cost of 99.9% erbium metal is about 21/g. Erbium is finding nuclear and metallurgical uses. Added to vanadium, for example, erbium lowers the hardness and improves workability. Most of the rare-earth oxides have sharp absorption bands in the visible, ultraviolet, and near infrared. This property, associated with the electronic structure, gives beautiful pastel colors to many of the rare-earth salts. Erbium oxide gives a pink color and has been used as a colorant in glasses and porcelain enamel glazes. 

Chemical analysis was a hard job. It took time, certain operations had to be carried out hundreds of times, and, said Cleve, it wasn t until after many years of work I [...] finally succeeded to isolate the real erbium earth The otherwise unknown chemist J. A. Alen from Uppsala University remembered that after 2V, year the salt was still completely intact. Nilson started with 10 kilos of the rare mineral euxenite, in order to produce 20 grams of ytterbium, and he needed 68 decomposing series, which was trying and time-consuming. ... 

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