Atomic erbium

Note that the nuclear charge of the erbium atom (M = Er) does not affect the choice of an. One obtains the following energy constraints for the two cluster models ... 

In the above inequalities the electronic energy of the erbium atom is much lower than that of cluster models (aas) and (asa). Although the coefficients 1/14 and 1/13 of terms involving Ee(Er) are small, the large negative value of Ee(Er) renders the calculated energy bounds rather loose and of little practical value. 

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. 

Erbium - the atomic number is 68 and the chemical symbol is Er. The name derives from the Swedish town of Ytterby (about 3 miles from Stockholm), where the ore gadolinite (in which it was found) was first mined. It was discovered by the Swedish surgeon and chemist Carl-Gustav Mosander in 1843 in an yttrium sample. He separated the yttriiom into yttrium, a rose colored salt... 

Terbium - the atomic number is 65 and the chemical symbol is Tb. The name derives from the village of Ytterby in Sweden, where the mineral ytterbite (the source of terbium) was first found. It was discovered by the Swedish surgeon and chemist Carl-Gustav Mosander in 1843 in an yttrium salt, which he resolved into three elements. He called one yttrium, a rose colored salt he called terbium and a deep yellow peroxide he called erbium. The chemist Berlin detected only two earths in yttrium, i.e., yttrium and the rose colored oxide he called erbium. In 1862, the Swiss chemist Marc Delafontaine reexamined yttrium and found the yellow peroxide. Since the name erbium had now been assigned to the rose colored oxide, he initially called the element mosandrum (after Mosander) but he later reintroduced the name terbium for the yellow peroxide. Thus the original names given to erbium and terbium samples are now switched. Since Bunsen spectroscopically examined Mosander s erbium (now terbium) sample and declared that it was a mixture, the question of who actually discovered terbium, Mosander or Delafontaine remains unresolved to this day. 

Thulium - the atomic number is 69 and the chemical symbol is Tm. The name derives from Thule, the earliest name for the northern most part of the civilized world - Scandanavia (Norway, Sweden and Iceland) . It was discovered in 1879 by the Swedish chemist Per Theodor Cleve in a sample of erbium mineral. It was first isolated by the American chemist Charles James in 1911. 

ISOTOPES There are 39 isotopes of erbium, six of which are stable Er-162, Er-164, Er-166, Er-167, Er-168, and Er-170. These six isotopes make up the total atomic weight (mass) of erbium, and all the other isotopes are artificially made and short-lived. Their half-lives... 

Erbium may be analyzed by atomic absorption or emission spectrophotometry. Other instrumental analyses involve ICP-MS and x-ray techniques. 

Cleve s fame rests chiefly, however, on his discoveries among the rare earths. After obtaining some erbia from which all the ytterbia and scandia had been removed, and after noticing that the atomic weight of the erbium was not constant, he succeeded in resolving the earth into three constituents erbia, holmia, and thulia (21). The absorption bands of holmium had already been noticed by the Swiss chemists M. Delafontaine... 

Johnson et al. (55) observed energy transfer from erbium to thulium and from erbium to holmium ions in crystals. They were able to obtain substantial decreases in laser thresholds because of this energy migration. The fluorescent lifetime of the 3//4 state of thulium in CaMo04 containing 0.75 atomic per cent erbium and 0.5 atomic per cent thulium as inferred from the time delay before the onset of laser oscillation is 900 /xsec at both IT and 20°K. 

Atomic number Symbol Element 21 Sc Scandium 39 Y Yttrium 57 La Lanthanum 58 Cfc Cerium 59 Pi Praseodymium 60 Nd Neodymium 61 Pm Promethium 62 Sm Samarium 63 Eu Europium 64 Gd Gadolinium 65 Tb Terbium 66 Dy Dysprosium 67 Ho Ilolmium 68 Er Erbium 69 Tm Thulmm 70 Yb Ytterbium 71 Lu Lutetium... 

Atomic number 69 Standard state Tm (c) Erbium Atomic weight 169.4... 

By using the intensity difference curve the light atom interactions can be eliminated and the RDF, including only interactions involving the metal ions, can be calculated. The results, referred to the erbium(III) solutions, are shown in Fig. 23 for three nitrate solutions of different compositions, including the 2.9 M solution illustrated in Fig. 22. The intramolecular N03 interactions together with all other nonmetal interactions are now eliminated and the first coordination peak appears as a separate peak. Its shape, however, depends on the composition of the solution, contrary to what was found for perchlorate solutions of similar compositions, and in comparison with these it is significantly broadened. For the 1 M solutions the difference is small but it becomes much more pronounced, when the concentration of nitrate ions is in-... 

He went through some strange, dexterous movements with his spectroscope, followed by short rapid calculations on paper. Turning to the French savant, Moseley told him the complete story of the rare earths which had taken Urbain months of laborious analytical operations to find out for himself. Erbium, thulium, ytterbium and lutecium, of atomic numbers 68, 69, 70, and 71, were present, but the element corresponding to 61 was absent. 

From a structural standpoint, the rare earth sulfides have several polymorphic forms (20), whose stability regions are represented in Figure 3. The high temperature form (y) exists from lanthanum to dysprosium. It is cubic and is of the Th3P4 type, with a defect structure. In each unit cell, there are 102/3 metal atoms which are distributed at random among the 12 sites of the metal lattice. The structures of the low temperature a and f forms are not yet known. The structure of the 8 form, which is peculiar to dysprosium, yttrium, and erbium, is monoclinic (20). The three last forms have low crystal symmetry, and certainly have no vacant lattices. 

---