Lutetium is the last member of the rare earth series. Lutetium is available as metal and compounds with purities from 99% to 99.999% ; metals in the form of foil, sputtering target, and rod, and compounds as submicron and nanopowder. Unlike most rare earths it lacks a magnetic moment. It also has the smallest metallic radius of any rare earth. It is perhaps the least naturally abundant of the lanthanides. It is the ideal host for x-ray phosphors because it produces the densest known white material, lutetium tantalate (LuTaO4). It is utilized as a dopant in matching lattice parameters of certain substrate garnet crystals, such as indium-gallium-garnet crystals due its lack of a magnetic moment.
Oxides are available in forms including powders and dense pellets for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Lutetium is available in soluble forms including chlorides, nitrates and acetates. These compounds are also manufactured as solutions at specified stoichiometries.