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This chapter begins with a description of the characteristic properties of the lanthanide elements, including their metallic and ionic radii (lanthanide contraction), crystal structures, oxidation states, electronic states, and magnetic properties. Their oxides and halides, and the coordination geometry of their cations are discussed. The section on organometallic compounds of the lanthanides is mainly concerned with those with cyclic organic ligands such as benzene, cyclopentadienyl, or cyclooctatetraenyl groups. The chapter concludes with a section on the reduction chemistry of the +2 oxidation state.

Once a leader in the production and trading of rare earths, the United States relinquished the reins to China in the 1990s. The People’s Republic of China declared rare earths “protected and strategic materials” and proceeded to control production and processing, introduced export quotas, and sought to dominate the supply chain for crucial applications. It also made investments in mines worldwide. The 2010 crisis caused a parabolic rise in prices, leading the United States, the European Union, and Japan to file a complaint against China at the World Trade Organization, in 2012, and to launch trilateral cooperation workshops, starting in 2011, to promote recycling, substitution, and innovation. China lost its WTO appeal and removed the export quotas in May 2015. The market corrected itself, and it may seem today that China lost an initial battle; but closer examination indicates that it may not have lost the war.

Rare earths are seventeen elements essential for hundreds of applications in renewables, high-tech, and defense. They include the family of lanthanide elements, as well as yttrium and scandium, and are divided into two main categories: light and heavy. They are called “rare” because of the low concentrations in which they are found and because it is difficult to mine and process them. This chapter catalogues a range of their most important uses for different industries and provides an overview of processing techniques and the serious environmental risks that accompany them. Finally, it examines the possibilities and limitations of recycling and substitution.

The colours of many minerals are determined by transition metal impurities, and such impurities demonstrate a wide range of magnetic and optical behaviour. This chapter discusses the systematics of the behaviour and the extent to which theory is effective in predicting what happens. It details coupling schemes, iron-group ions in cubic symmetry, the cubic field splitting, and rare-earth ions.

This chapter chronicles the development of the study of ferro- and ferri-magnetic materials through Compton scattering, comparing the information with that obtainable through neutron scattering methods. The experimental technique, using circularly polarized synchrotron radiation, is explained. Work in the following categories is reviewed: 3d transition metals, alloys, and compounds; Heusler alloys; amorphous alloys; 4f rare earth metals and alloys, and uranium compounds.

In 2010, rare earths were thrust into geopolitical prominence overnight as a result of a territorial incident between Japan and China. China’s “unacknowledged” and short-lived rare earths embargo against Japan, coupled with China’s decision to sharply reduce export quotas of these materials to all industrial nations, brought home the potential dangers of its near-monopoly position on their production and export. Prices skyrocketed and the international outcry intensified because the seventeen rare-earth elements are critical inputs for high-tech, defense, and renewable energy sources. Given their centrality, the rare-earth crisis is not merely a trade dispute. It raises questions about China’s use of economic statecraft and the impacts of growing worldwide resource competition while pointing to the complexities facing policymakers as they develop strategies and responses in an increasingly globalized world.

This chapter traces the changes in the political economy with respect to “rare earths,” which are mineral-laden compounds that are hard to find. The discovery of one such “rare earth”—monazite, a phosphate compound composed of several rare earth elements, including radioactive thorium, a potential source of nuclear fuel—in large quantities in the beach sands of a stretch of land between the coastal towns of Kollam and Nagercoil in the erstwhile princely state of Travancore (now Kerala) in India marks another aspect of the the Cold War, viz., the technopolitics of the rare earths. The chapter shows how India—by harnessing the extraordinary global demand of Thorium as an atomic fuel in the heat of the Cold War—was able to transform the rare earths into a strategic national resource. Thorium also, the author posits, reinforced India’s territorial sovereignity.

Channels of radiative recombination in bulk crystalline semiconductors: a short overview is at first given, then the following processes and their microscopic origin are analyzed: recombination of free electron–hole pairs (both in direct and in indirect bandgap); recombination free electron(hole)–neutral acceptor(donor); recombination of donor–acceptor pairs; two‐photon excited luminescence; luminescence from semiconductors doped with transition metal and rare earth ions. The accent is put on typical lineshape (e.g. Maxwell–Boltzmann) and intensity dependence of each particular process. The role of the density of states, the transition matrix element and suitable occupancy in bands is addressed. Selected examples of experimental emission spectra illustrate the exposition. Discussion of various types of excitons and their radiative recombination is postponed to Chapter 7.

Fossil bones and teeth are the last physical remains of once-living vertebrates, and the chemistry of these fossils at least in part reflects the biochemistry of the individual. If the mineral phase of bone remains unaltered during diagenesis and fossilization, then the bone will contain a biogenic signal that can be used to infer directly physiological, dietary, and climatic information about the animal and its environment. Geochemical analyses of trace elements are particularly well suited to the study of bonebeds. Trace element analyses can be used to assess the extent of mixing within a bonebed, to determine the origin of reworked bones within a mixed assemblage, and to help distinguish between catastrophic and attritional modes of accumulation. This chapter discusses the trace element geochemistry of bonebeds, focusing on the importance of diagenesis in understanding geochemical taphonomy, the use of rare earth elements in geochemistry, applications of geochemical provenance techniques in the fossil record, reworking of bones, and paleoenvironmental reconstruction.

Climate change is opening the navigational potential of the Arctic, attracting the interest of major commercial powers such as China, despite the lack of any particular historical linkages they may have to the region. Investors from resource-extractive nations like Australia are similarly attracted to Arctic areas such as Greenland because of their potential for mineral investment. These unusual connections for economic expediency should be harnessed as a means of “creative diplomacy,” as noted by former Australian prime minister Kevin Rudd. Furthermore, instead of seeing China as a competitor or hegemonic power, there is an opportunity to apply some of the lessons of Antarctic scientific cooperation to the Arctic as well. This chapter documents the various pathways for cooperation that might be followed as climate change provides new economic opportunities, particularly around extraction of rare earth elements. We also recognize the ecological challenges in the Arctic of any resource extraction, and hence the confluence of science and economics is recognized as essential in fostering a sustainable outcome for the development of the region.

A microscopic approach to deriving the structure, energies and systematics of collective states from the shell model appears in two forms, the Tamm-Dancoff approximation and the random phase approximation (RPA). The reader who is at all versed in nuclear structure physics may have encountered calculations carried out in the RPA or references to such techniques. This chapter presents a simple derivation and discusses the basic ideas involved, and then illustrates the techniques with a particular calculation for rare earth nuclei. The end result is a set of predictions for comparison with experiment as well as a deeper understanding of the microscopic nature of many aspects of collective behavior. It allows predictions of the basic structure of particular collective states without detailed or complex calculations. Simply by visual inspection of a Nilsson diagram, the energy behavior of collective vibrations can be predicted. This chapter also discusses the structure of collective vibrations and vibrations in deformed nuclei.

In this chapter, a theoretical and practical survey of the state of the fiber laser art is presented. It begins with an analysis of optical fibers, and introduces this subject by studying a simple “slab” optical waveguide, the treatment of which is considerably more tractable than that of a fiber. Several practical aspects of fiber technology, such as fiber dispersion and coupling, are mentioned, and a number of fiber-optic components are described. A necessarily qualitative discussion of the atomic physics of rare earth ions in a glass medium is provided, and the level structures of several specific rare-earth-doped fibers are discussed. The chapter ends with a description of some current continuous-wave fiber lasers (leaving mode-locked fiber lasers for a later chapter).

In the recent WTO case involving Chinese restrictions on exports of rare earths, the question was whether the restrictions could be excepted under GATT Article XX(g). In order to qualify for an exception under Article XX(g), the relevant measure must (i) relate to the conservation of exhaustible natural resources; (ii) be made effective in conjunction with restrictions on domestic production or consumption; and (iii) satisfy the requirement of the chapeau of Article XX to the effect that it is not applied as arbitrary or unjustifiable discrimination, or as a disguised restriction on trade. The Appellate Body confirmed the panel’s approach to Article XX(g) in a way that makes it unclear how this defence will operate in the future.

This chapter delivers a mixed forecast for the impact of population growth on mineral resources. On one hand, technological advancement has allowed humans to extract resources from places that previously were impossible to explore. Deep-water resource mining has grown, and estimates of overall resource reserves are continually being adjusted upward. On the other hand, extracting minerals has implications for climate change. The chapter explains that mineral extraction is not only energy intensive itself, but that any vectors used to reduce climate change will require mineral resources to implement. Without major changes, a growing population will accelerate mineral demands, with cataclysmic consequences. Recycling offers an important opportunity; for some metals, such as aluminium, reuse requires only 5% of the energy input of initial extraction. The planet may not be full, the chapter concludes, but ‘new ways of designing, using, and re-manufacturing or reusing materials and products must be developed.’

This chapter reviews the development of bulk HTS cuprates for high-magnetic-field applications. Trapped magnetic fields realised to date have exceeded the requirements for many applications. These new type of permanent magnets are being used in high-field generators for laboratory experiments, magnetic separators for purification of water, superconducting motors, and magnetron sputtering devices. With the advent of a new class of superconductors based on lighter rare earths (LREs) and possessing large J_c(H) values in the liquid oxygen temperature range, it has been possible to perform levitation applications at these temperatures. Various approaches for fabrication of bulk HTS for practical use are discussed, including strategies for optimising their superconducting and mechanical properties. At present, it is the latter that seem to set a limit on the optimum magnetic field that can be trapped without the material cracking, although resin impregnation holds significant promise for solving this problem.

Artist/scientist Erin Espelie was trained at Cornell University as a biologist, but turned down opportunities to study biology at the graduate level at Harvard and MIT in order to explore the New York City theater scene, before finding her way into independent, “avant-garde” filmmaking, first exploring her interests in biology and the history of science in a series of short films, then producing the remarkable essay-film The Lanthanide Series (2014), which explores the importance of the “rare earths” (the elements with atomic numbers 57–71) for modern communication and informational technologies. The imagery for The Lanthanide Series was recorded, almost entirely, off the reflective surface of an iPad. In her work as a moving-image artist, Espelie combines poetry, science, environmental politics, and modern digital technologies within videos that defy traditional knowledge categories. She is currently editor in chief for Natural History magazine and a director of the NEST (Nature, Environment, Science & Technology) Studio for the Arts at the University of Colorado-Boulder.

With so many stars in the galaxy, it might be assumed there must be advanced alien civilizations out there somewhere, but Enrico Fermi pointed out that if this were the case we should have been visited long ago, yet there is no evidence that this has happened. This puzzle is known as the Fermi paradox. Several explanations have been proposed. One possibility is that advanced civilizations do arise, but rapidly disappear due to their self-destructive tendencies. Another possibility is the zoo hypothesis—the aliens are here, but do not reveal themselves. There is also the rare Earth hypothesis which claims the Earth has unique features required for the evolution of intelligent life, so we really are the first advanced civilization in the galaxy.