Properties of Rare-Earth Metals

The arc and spark spectra of the individual lanthanides are exceedingly complex. Thousands of emission lines are observed. For the trivalent rare-earth ions in soUds, the absorption spectra are much better understood. However, the crystal fields of the neighboring atoms remove the degeneracy of some states and several levels exist where only one did before. Many of these crystal field levels exist very close to a base level. As the soUd is heated, a number of the lower levels become occupied. Some physical properties of rare-earth metals are thus very sensitive to temperature (7). 

The rare-earth metals are of rapidly growing importance, and their availability at quite inexpensive prices facilitates their use in chemistry and other applications. Much recent progress has been achieved in the coordination chemistry of rare-earth metals, in the use of lanthanide-based reagents or catalysts, and in the preparation and study of new materials. Some of the important properties of rare-earth metals are summarized in Table 18.1.1. In this table, tm is the atomic radius in the metallic state and rM3+ is the radius of the lanthanide(III) ion in an eight-coordinate environment. 

Some physical properties of rare earth metals [2],... 

A.J. Freeman, Magnetic Properties of Rare Earth Metals, ed. R.J. Elliot, Plenum Press, London and NY, 1972. 

The unique luminescent properties of rare earth metal clathrochelates have been used in the development of luminescent materials (luminophores and laser materials). The luminescence of these clathrochelates in solution makes their application as biological probes and concentrators of the luminescence (i.e., the antenna effect ) promising. These complexes can also serve as efficient molecular devices to convert UV light absorbed by the ligand to lanthanide ion luminescence in the visible region. Even in very dilute (10-5 mol l-i) solutions, the conversion of irradiated photons to luminescent ones has been observed to occur at a rate of approximately 1%. For rare earth metal aqua ions at the same concentration, the efficiency of conversion is equal to 4 x IQ- % [212, 390-392]. 

Structural and Electronic Properties of Rare Earth Metal Systems... 

Magnetic properties of rare earth metal-transition metal-indides with CsCl superstructures or Heusler type structure... 

Dimmock, J.O., A.J. Freeman, and R.E. Watson, 1966, Electronic band structure and optical properties of rare earth metals, Abeles, F. ed.. Proceedings of the International Colloquium on Optical Properties and Electronic Structure of Metals and Alloys, Paris, 1965, (North-Holiand Publishing Co., Amsterdam), pp. 273-245. 

Freeman, A.J., J.O. Dimmock, and R.E. Watson, 1966, The augmented plane wave method and the electronic properties of rare earth metals, Ldwdin, P.O., ed.. Quantum Theory of Atoms, Molecules and the Solid State, a Tribute to John C. Slater (Academic Press, New York), pp. 361-380. 

Freeman, A.J., 1972, Energy band structure, indirect exchange interactions and magnetic ordering, Elliott, R.J., ed.. Magnetic Properties of Rare Earth Metals (Plenum Press, London and New York), pp. 245-333. Gaspar, R 1954, Acta Phys. Acad. Sci. Hung. 3,263. 

Bleaney, B., 1963, J. Appl. Phys. 34, 1024. Bleaney, B., 1972, Hyperfine interactions, in Elliott, RJ., ed.. Magnetic properties of rare earth metals (Plenum Press, London and New York) pp. 383-420. 

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