Yttrium is a Block D, Group 3, Period 5 element. The electronic configuration is [Kr] 4d¹ 5s². In its elemental form yttrium's CAS number is 7440-65-5. The yttrium atom has a radius of 177.6.pm and it's Van der Waals radius is 200.pm. Yttrium has the highest thermo-dynamic affinity for oxygen of any element. This characteristic is the basis for many of its applications. While not part of the rare earth series, it resembles the heavy rare earths which are sometimes referred to as the “yttrics” for this reason. Another unique characteristic derives from its ability to form crystals with useful properties. Yttrium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra high purity); metals in the form of foil, sputtering target, and rod, and compounds as submicron and nanopowder.

Aluminum is a Block P, Group 13, Period 3 element. The electronic configuration is [Ne] 3s² 3p¹. In its elemental form aluminum's CAS number is 7429-90-5. The aluminum atom has a radius of 143.2.pm and it's Van der Waals radius is 200.pm. Aluminum is a silvery-white metal that possesses many desirable characteristics. It is light, nonmagnetic and nonsparking. It stands second among metals in the scale of malleability, and sixth in ductility. It is extensively used in many industrial applications where a strong, light, easily constructed material is needed. Although it's electrical conductivity is only about 60% that of copper, it is used in electrical transmission lines because of its light weight. Pure aluminum is soft and lacks strength, but alloyed with small amounts of copper, magnesium, silicon, manganese, or other elements impart a variety of useful properties. These alloys are of vital importance in the construction of modern aircraft and rockets. Aluminum, evaporated in a vacuum, forms a highly reflective coating for both visible light and radiant heat.