Economic relationships and market trends of the rare earths
Abstract This paper considers the market trends of the rare earths and how they are strongly influenced by the by-product/co-product nature of their mining and processing. The two main economic minerals for the rare earths are bastnasite and monazite. Monazite is primarily a by-product of mining ilmenite and rutile and is affected by changes in these markets as well as the presence of thorium. Bastnasite is a byproduct of mining iron ore in China and a stand-alone product in the USA. The paper will use conceptional relationships and empirical data to delineate the various by-products/co-products relationships and how they determine observed market behavior.
Catalysis: A growing market for rare earths☆
Abstract The purpose of this paper is to review the current applications of rare earths in catalysis and their corresponding markets and to examine the uses that may be developed commercially in future. Nowadays, it is well known that minor additions of rare earths can provide a beneficial effect for various catalytic systems. Thus, the introduction, by exchange, of rare earth cations improves the thermal stability of the Y zeolite contained in fluid cracking catalyst (FCC). Another example is the addition of rare earth oxides to automotive post-combustion catalysts in order to stabilize the alumina support. Today these applications represent the two main markets for rare earths in catalysis. However, specific catalytic properties and behavior, such as a particular orientation of the selectivity in CO + H2 reactions and a promotional effect in polymerization reactions, promise potential future applications and a wider recognition of rare earths in the catalytic field.
Magneto-optic properties of rare earth iron garnet crystals in the wavelength range 1.1-1.7μm and their use in device fabrication
The wavelength and temperature dependence of the Faraday rotation together with the optical loss spectra of yttrium, gadolinium, terbium, dysprosium, holmium, erbium and ytterbium iron garnets are reported for wavelengths in the range 1.1-1.7 mu m. It is demonstrated that the Faraday rotation of all the iron garnets decreases with increasing wavelength with the exception of ytterbium iron garnet which, for wavelengths in excess of approximately 1.3 mu m, possesses a wavelength independent Faraday rotation of 5.7+or-0.3 degrees mm-1. The performance of magneto-optic switches, isolators, modulators and deflectors constructed using each of these materials is discussed with particular emphasis on their operation at 1.3 mu m and 1.55 mu m, the wavelengths of interest in current optical fibre systems. It is concluded that whilst yttrium iron garnet or holmium iron garnet are best suited to the fabrication of devices operating at single wavelength, for broadband operation ytterbium iron garnet is to be preferred.