Rare earth metal fundamentals

The rare earth metals form hydrides readily and a number of studies have been performed on these materials (143). The dihydrides of the rare earths form in CaF2-type structure. The crystal field problem has been applied to characterize the fundamental role of hydrogen in these compounds (144-149). The information accumulated for several dihydrides seems to favor the anionic model, namely, that hydrogen accepts an electron to become negatively charged. We will illustrate the results on PrH2 and ErH2. 

Amoco researchers began to research various catalytic additives that could prevent Mn02 precipitation while permitting one to operate at a lower Br/Co -I- Mn ratio. Rare earth metal salts, particularly Ce(OAc)3 at Co/Ce =10 1, were discovered to inhibit Mn02 precipitation even when very low Br/(Co + Mn) ratio was employed (<0.5) [62, 63]. A fundamental study of the unwanted production of Mn02 was later pursued by the group of Bakac [56]. Mn indeed can access the oxidation state by either direct oxidation of Mn(lll) or reduction from Mn(VII). Mn(IV) can also oxidize bromides andMn(ll). 

As a fundamental class of compounds in the fields of synthetic solid-state (and also molecular) chemistry, cyanamides and carbodiimides have gained increasing attention within the past decade. Because of their 2-fold anionic charge, both cyanamide and carbodiimide structural units allow the realization of nitrogen-based pseudo-oxide chemistry since NCN is able to replace in a wide variety of novel materials. A number of alkali metal, alkaline-earth metal, main-group metal,divalent transition-metal, trivalent rare-earth metal,and also triva-lent transition-metal cyanamides/carbodiimides were obtained following different synthetic routes. The only carbodiimide containing divalent lanthanide ions was reported by DiSalvo et al., who found that EuNCN is isostructural to the already known a-SrNCN. ... 

This chapter reviews the available knowledge of the bulk magnetic and transport properties of the rare earth metals with a particular emphasis on the ways in which these macroscopic properties may be interpreted to improve our understanding of the fundamental microscopic interactions. The review comprises five basic components in section 2 we discuss the magnetization and susceptibility of these metals followed by their magnetic anisotropy in section 3 and magnetostriction in section 4. Section 5 considers the electrical resistivity, whilst section 6 deals with magnetoresistance and the Hall effect. 

Elastic properties serve an obvious utility in mechanics of materials, e.g., stress-strain relations and dislocation characteristics (Fisher and Dever, 1967 Fisher and Alfred, 1968). Moreover, elastic properties and their temperature dependencies provide important information and understanding of such physical characteristics as magnetic behavior, polymorphic transformations, and other fundamental lattice phenomena. In this section the elastic properties and their temperature dependencies are presented for all the rare earth metals except promethium, for which there is no data. To the writer s knowledge this is the first one-source compilation of the temperature dependencies of the elastic properties of the rare earth metals. 

Homogeneous Catalysis Lanthanide Halides Organometallic Chemistry Fundamental Properties Tetravalent Chemisiry Inoiganic Tetravalent Chemistry Organometallic The Divalent State in Solid Rare Earth Metal Halides The Electronic Structure of the Lanthanides. 

The Mannich and related reactions provide one of the most fundamental and useful methods for the synthesis of P-amino ketones or P-amino esters. Three-component Mannich-type reactions of aldehydes, amines, and silyl enol ethers have been developed. With the development of green solvent systems, this reaction was also examined in a fluorous phase using perfluorinated rare earth metal salts including Sc(0S02C8Fi7)3 [5]. A characteristic point of this system is that it can be reused many times without reloading a new catalyst. There are also many reports on other scandium-catalyzed Mannich reactions. For example, Sc(OTf)3 was found to be an efficient catalyst for the three-component Mannich-type reactions of aromatic aldehydes, ketones, and nitriles in the presence of acetyl chloride (Scheme 12.3) [6]. 

Fischbach, A., Anwander, R., 2006. Rare-earth metals and aluminum getting close in Ziegjer-type organometallics. In Nuyken, O. (Ed.), Neodymium Based Ziegler Catalysts—Fundamental Chemistry. Springer, Berliiu... 

Transition and rare earth metal oxides are the fundamental ingredients for the advanced smart and functional materials. Many functional properties of inorganic materials are determined by the elements with mixed valences in the structure unit [1], by which we mean that an element has two or more different valences while forming a compound. The discovery of high-temperature superconductors is a successM example of the mixed valence chemistry, and... 

Abstract This chapter provides an overview of major corrosion testing and analysis techniques and their applications in corrosion inhibitor research, with a particular focus on electrochemical evaluation of corrosion protection by rare earth metal (REM) compounds. Attempts are made to discuss fundamental issues in inhibitor test design such as limitations in corrosion measurement techniques and challenges that may lead to the reporting of inaccurate corrosion rates and patterns. 

Table 2. Magnetic Fundamentals of Rare-Earth Transition-Metal Thin Films...

The extraction of metals fundamentally relies on their availability in nature. Three terms are important while one refers to availability. One is the crustal abundance and the other two are the terms resources and reserves. The average crustal abundance of the most abundant metals, aluminum, iron and magnesium, are 8.1%, 5.0% and 2.1% respectively. Among the rare metals titanium is the most abundant, constituting 0.53% of the Earth s crust No metal can be economically extracted from a source in which its concentration is the same... 

Trigonal ML3 metal complexes exist as optically active pairs. The complexes can show enantiomeric selective binding to DNA and in excited state quenching.<34) One of the optically active enantiomers of RuLj complexes binds more strongly to chiral DNA than does the other enantiomer. In luminescence quenching of racemic mixtures of rare earth complexes, resolved ML3 complexes stereoselectively quench one of the rare earth species over the other. 35-39 Such chiral recognition promises to be a useful fundamental and practical tool in spectroscopy and biochemistry. 

The metal has very little commercial use. In elemental form it is a laser source, a portable x-ray source, and as a dopant in garnets. When added to stainless steel, it improves grain refinement, strength, and other properties. Some other applications, particularly in oxides mixed with other rare earths, are as carbon rods for industrial hghting, in titanate insulated capacitors, and as additives to glass. The radioactive isotope ytterbium-169 is used in portable devices to examine defects in thin steel and aluminum. The metal and its compounds are used in fundamental research. 

Ever since the foundations of spectroscopy were laid the problem of the relationship between the optical spectra emitted or absorbed by matter and the microscopic properties of the matter has been regarded as a fundamental problem. A class of very interesting systems with this regard is provided by non-metallic compounds of rare-earth ions with partially filled 4f shells. Their rich electronic structure is only weakly perturbed by the environment and provides a detailed fingerprint of the surrounding arrangement of atoms and their interactions with the f-electrons. 

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