R&D: Chromium-Based Coating–Substrate Systems for Ceramic Data Storage Media

SSRN has published an article written by E. Peck, B. I. Hajas, TU Wien, Institute of Materials Science and Technology, Vienna, Austria, L. Kreuziger, Cerabyte GmbH, Vienna, Austria, J. Amann, R. Fürbacher, G. Liedl, TU Wien, Institute of production engineering and photonic technologies, Vienna, Austria, C. Pflaum, Cerabyte GmbH, Vienna, Austria, P. H. Mayrhofer, and , A. Kirnbauer, TU Wien, Institute of Materials Science and Technology, Vienna, Austria.

Abstract: “Sustainable long-term data storage is increasingly important, as most stored data is “cold”, rarely accessed or modified. Conventional solutions, such as HDDs and SSDs, rely on energy-intensive server farms to maintain data integrity. This study investigates Cr-based coatings—Cr, CrN, Cr2O3, CrB2, and (Al,Cr)N—deposited on sapphire and polycrystalline Al2O3 via magnetron sputtering as potential ceramic data carriers. X-ray diffraction confirmed the expected crystal structures, while nanoindentation revealed hardness values ranging from 11.4 ± 0.2 GPa (Cr) to 30.0 ± 0.6 GPa ((Al,Cr)N), with indentation moduli from 379 ± 5 GPa (Cr) to 495 ± 24 GPa (CrB2). Surface roughness measurements showed Ra = 1–3 nm for most coatings, with CrB2 being rougher (Ra = 9 nm), highlighting the influence of surface quality on laser ablation. Femtosecond laser experiments at wavelengths of 343, 515, and 1030 nm identified CrN on sapphire as the most promising system. The 25-nm-thin film exhibited the lowest ablation threshold of 114 mJ/cm2 at λ = 343 nm with a single pulse, increasing nearly linearly with thickness and remaining lower than for polycrystalline Al2O3. Ablation thresholds decreased with increasing pulse number (power-law exponent k = −0.276 to −0.360), enabling lower-power lasers or higher writing speeds. CrN on sapphire combines low ablation threshold, smooth surface, and high mechanical stability, allowing fast, energy-efficient data writing. Once written, the data requires virtually no energy to maintain, offering a sustainable, durable alternative to conventional storage media.“