One of the main purposes of the handbook is to place archival material at a time and in a readily available form for the promotion of current research using rare earth elements. Gladyshevsky, Bodak and Pecharsky have collected together summaries of the literature of the last quarter of the century3; on the phase equilibria and crystal chemistry of ternary metal systems containing a rare earth element with a group III, IIIb, or IV metal moiety and a transition metal. Elemental analysis by atomic emission and inductively coupled plasma mass spectrometry are shown by Houk to be the techniques of choice for the analysis of rare earth materials.
The inclusion and effects of rare earth elements on plant and animal life are considered. Chabot, Crystal structures and crystal chemistry of ternary rare-transition metal boides, silicides and homologues 113. Rogl, Phase equilibria in ternary and higher-order systems with rare earth elements" and boron 335 50.
Appendix: Atomic Coordinates for Structure Types Found in Rare Earth Ternary Systems with Metallic Elements 179 This research deals with the results of phase equilibria and crystal structures found in rare earth ternary systems.
E/Ill Ce3Atl
LuNi 3
Emes-Mysenko, E.I., 1971b, Investigation of some ternary lanthanum-3d metal-aluminum systems in low-lanthanum regions, Ph.D. Sokolovskaya, 1974b, Physicochemical investigation of alloys in the system ruthenium-aluminum-scandium, palladium-aluminum-scandium, Manuscript submitted to VINITI, no. Zarechnyuk, 1983b, Crystal structure of IMC in Eu, Sr, Ba-Cu-A1 systems, in: Chetvertaya Vsesoyuzn.
Rykhal, R.M., 1972a, Phase equilibria and crystal structure of compounds in the ternary systems yttrium-3d transition metal-aluminum, Ph.D. Rykhal, R.M., 1978, The new representatives of the structural types Ce3CosSi and Mo2NiB z in the rare earth-nickel-aluminum systems, in: Tretya Vsesoyuzn. Zarechnyuk, 1974, The compounds with crystal structure of the ThMnla type in the systems R-Fe-A1, in: Vtoraya Vsesoyuzn.
Phase equilibria were investigated in 30 ternary systems and the existence of 210 rare earth ternary gallides was established. The only ternary compound Scl.3Cr0.7Ga with an unknown crystal structure was found by Gavrylenko and Markiv (1978a) during the study of the phase diagram of the S c - C r - Ga system (Fig. 68).
7/% / scG°2
A total of seven new ternary compounds were found by Gavrylenko and Markiv (1979) during a phase diagram study (Fig. 73).
ScGo
PrGo Pr2G°
R-M-{In, Tl} systems
A total of 117 ternary compounds were found in the 17 R - M - G e ternary systems while deriving the phase diagrams. The crystal structure has been determined or confirmed for 9 of the total of 15 ternary compounds found. Starodub, P.K., 1988, Phase equilibria, crystal structures and some physical properties of the ternary compounds in the systems Tb-Fe,Co,Ni,Gu-Ge, Ph.D.
Phase equilibria were investigated for only 7 ternary R - M - Sn systems and a total of 61 ternary compounds were found. The existence of a further 163 ternary compounds (they are listed in Table 5) was reported for a further 108 partially studied R-M-Sn ternary systems without any phase equilibrium details. The total number of ternary compounds is 10, for 6 of them the crystal beam was resolved, and for 1 only the lattice parameters were determined: (1) -- CeNisSn (new type of crystal structure according to Skolozdra et al.
The existence of a total of 89 ternary compounds (49 of which with a defined crystal structure) has been reported.
LaCu 6
Another ternary compound, LazMg3Zn3, with a cubic unit cell, a = 7.145, was previously reported by Melnyk et al. Substitution of Co atoms by Cu in the continuous solid solution Ce(Co, Cu)5 increased the unit cell constant. TERNARY RARE EARTH SYSTEMS WITH METALLIC ELEMENTS 131 Cu. 1979a) reported the phase diagram shown in Fig. 1986) found no ternary compounds during the phase equilibrium study (see Figure 155).
A small portion of the large cerium atoms are randomly mixed with the smaller atoms - Fe and Mo, at the Mn sites of the ThMn12 ST. The unit cell volume decreased linearly with the increase of the Pu content in the solid solution regions.
MgTZ~ \y~
The study and derivation of structure type relationships is one of the main tasks for crystal chemistry. This common bond is represented in the crystal structures of the compounds La2NiGe, Tm3NillGe4, EuCo2Ga3, C%NiGe2 and YCo3Sn. One of the atomic positions [12(k), see appendix] is statistically filled by Co and Sn.
The unit cell thus becomes orthorhombic, which is shown on the right side of the figure. However, the distortion does not only occur in the trigonal prisms, but is also concerned with the arrangement of the trigonal prism columns. 191 shows the scheme of the relative deformation of the CeLiG% trigonal prism columns arrangement in comparison with MgCuA12.
Thus, the c o m p o u n d structure can be described as "twinned through a mirror" slabs of the structure type S m s G e 4. The difference that can be seen concerns the relative length of the BaA14 slabs: it is ~ times longer in 7 .Structure types Gd6Cu8Ge s and Ce2Li2G % as inhomogeneous linear counterparts of MgCuA12 and A1B 2.
Two structures (see Fig. 201) can be described as the result of the two-dimensional interchange of the trigonal prisms, icosahedrons and half octahedra, connected together as shown. 2 structure type as two-dimensional packing of trigonal prisms, icosahedra and halves of the unfilled octahedra. TERNARY RARE EARTH SYSTEMS WITH METALLIC ELEMENTS 175 examples of the so-called "valence" (or interconfiguration) fluctuation state between the normal +3 valence and +2 (europium and ytterbium) or +4 (cerium) valence.
Deformation electron density (DED) map in the hexagonal [Ni2Ge4] compound YNi2Ge ~. The relationship of the unit cell dimension c with the silicon atomic parameter (z) and the Si-Si interatomic distance values (6) for RMgSi 2 compounds. In certain cases, the addition of a third component also makes it possible to compensate for the deficit of some rare earth elements and use them economically.
The R-M~-X systems
