Nuclear block metals formed

FIGURE 21.2 Primary mineral sources of metals. The s-block metals occur as chlorides, silicates, and carbonates. The d- and p-block metals are found as oxides and sulfides, except for the group 3B metals, which occur as phosphates, and the platinum-group metals and gold, which occur in uncombined form. There is no mineral source of technetium (Tc in group 7B), a radioactive element that is made in nuclear reactors. 

Figure 6.31 The structures of (a) dodeca-, (b) pentadeca-, and (c) octadeca-nuclear clusters templated by two IX4-H ions, a X5-X (X = C1, Br) ion, and Xe p r r r r r COj , respectively. Formal assembly of a 60-metal hydroxide complex featuring 26 vertex-sharing [Ln4(ti3-OH)4] cubane units. These cubane building blocks form six dodecanuclear squares and eight octadecanuclear hexagons [102]. (Redrawn from X. Kong et al, A chiral 60-metal sodaUte cage featuring 26 vertex-sharing [Er4(p.3-OH)4] cubanes, Journal of the American Chemical Society, 131, 6918-6919, 2009.)...

In conclusion, it may be said that the stumbling blocks in analysing heat capacity measurements on the rare earth metals are the difficulty of obtaining satisfactorily high purity samples and the current state of the theory for spin waves. There are too many unknown variables for unambiguous analysis. Nevertheless, in nearly all cases the nuclear contribution has been determined accurately, and for the majority some indication of the most likely form for the magnetic term exists. 

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