The purest form of aluminum is 99.99995%, also known as 6N5 MBE (molecular beam epitaxy) grade. This highest purity level achievable for aluminum is required for single-crystal thin film deposition.
About Aluminum Purity
Generally, the purity of aluminum is denoted in 'nines.' For instance, 4N (four nines) aluminum is 99.99% purity. This is a popular choice in several industrial applications due to the balance of purity and cost effectiveness. Typical use cases include capacitor foils and high-end electrical components production, where superior conductivity and resistance to corrosion are essential. Most importantly, 4N aluminum has few impurities, which ensures electronic device longevity and high performance.
Further up the scale, there is 5N aluminum (99.999%), which contains even fewer impurities than 4N. It's produced from 4N aluminum through a highly-precise, expensive refinement process. In comparison to 4N aluminum, 5N is more expensive, produced on a smaller scale, and typically made in smaller batches.
Beyond 5N Aluminum
After 5N, there are 5N5 (99.9995%) and 6N (99.9999%) aluminum grades. Each ascending grade requires more effort and cost to produce. The increased cost is due to the amount of aluminum discarded during the refinement process. In general, as aluminum is refined to higher purities, the yield from the starting weight decreases. For this reason, 6N is even more costly and time consuming to produce.
However, there is demand for ultra-pure forms in fields like electronics and thin film deposition. The summit of aluminum purity is 6N5 MBE grade, which boasts 99.99995% purity. The process for achieving 6N5 purity involves eliminating impurities to meet the stringent demands of MBE thin-film deposition. To guarantee this purity, it is necessary to pack each piece of 6N5 in sterilized, argon gas-filled packaging to prevent any contamination.
Single-Crystal Thin Film Deposition with 6N5 MBE Grade
The single-crystal thin film deposition involves the epitaxial growth of thin films using molecular beam epitaxy (MBE) or similar techniques. By utilizing 6N5 MBE grade aluminum as the starting material, manufacturers ensure the creation of high-quality, defect-free, thin films, which are essential for advanced semiconductor devices and nanotechnology applications.
The Chemical Properties of Different Aluminum Grades
In 4N aluminum, total non-aluminum elements (such as iron, silicon, copper, and magnesium) only make up a maximum of 100 parts per million (ppm). For 5N aluminum, this limit is reduced to 10 ppm, whereas for 6N aluminum, it's just 1 ppm. At 6N5 purity, the maximum total limit of non-aluminum elements is further limited to just 0.5 ppm.
Higher purities of aluminum are employed in specialized technological applications, such as high-precision optics and advanced scientific instruments. The lower impurity levels enhance thermal and electrical conductivity, making the material ideal for high-performance and sensitive environments.
For a deeper look at different aluminum purities and their applications, explore our comprehensive Aluminum Purities Guide. Discover the role of each of the aluminum grades in various industries and technological advancements.
Laurand supplies a wide range of high-purity and ultra-pure aluminum grades, from 4N through 6N5 MBE. Visit our store to learn more.