In thin film deposition processes like thermal evaporation, electron beam evaporation, and other evaporation systems, the quality of your coating depends not only on the deposition method but also on the evaporation materials you use. Metals, oxides, fluorides, and other compounds are available in various purity levels, often expressed in “N” ratings. Selecting the correct purity grade is crucial for achieving consistent performance, preventing defects, and managing costs efficiently. 

Some materials may also be sold under industrial or mechanical grades that differ significantly from the “N” system. 

Understanding Purity Grades 

The "N" system is a shorthand method of expressing chemical purity: 

Decimal annotations indicate a slightly higher precision within a grade, for applications where even fractional increases in purity impact performance—such as optical coatings, semiconductor devices, or protective coatings—these grades can justify the added cost. 

Zirconium is commonly designated as Grade 702, which is an industrial specification based on ASTM/ASME standards. Instead of reflecting a direct “N” purity value, this grade defines the material’s chemical composition and mechanical properties, including corrosion resistance and thermal stability. The designation ensures performance in demanding environments, such as nuclear reactors or chemical industry applications, making it distinct from the standard “N” classification. 

Why Purity Matters in Thin-Film Deposition

Film Quality

Impurities can alter a coating’s optical clarity, color accuracy, electrical conductivity, and adhesion to the substrate. Even minor contamination can lead to haze, color shifts, or reduced reflectivity in thin film coatings. 

Process Reliability

Inconsistent purity can lead to unpredictable deposition rates and variations in film thickness. Higher-purity materials help maintain stable evaporation characteristics, improving run-to-run reproducibility. 

Performance Lifespan

Coatings made from higher-purity materials generally exhibit greater stability over time, resisting environmental degradation and maintaining functional properties for longer periods. This is vital for applications in solar cells, display technologies, data storage devices, and quantum technologies. 

Section banner 1: Use an image of thin film deposition.  

Choosing the Right Purity Grade 

High Purity (5N) 

Mid-High Purity (4N) 

Standard Purity (3N) 

Lower Purity (2N)