The rare earths represent a group of chemical elements, the lanthanides, together with scandium and yttrium, which exhibit similar chemical properties. They are strategically important to developed and developing nations because they have several applications in catalysis, the defense industry, aerospace, the materials and life sciences and in sustainable energy technologies. The Handbook on the Physics and Chemistry of the Rare Earths is a continuing authoritative series that deals with the science and technology of the rare earth elements in an integrated manner. Each chapter is a comprehensive, up-to-date, critical review of a particular segment of the field. The work offers the researcher and graduate student a complete and thorough coverage of this fascinating field.