Hafnium (IV) oxide

Hafnium (IV) Oxide, UV Grey Granules (Patinal®) is a high‐purity material produced in granule form with particle sizes ranging from 1 to 4 mm (>80% by mass) that is used for making thin films and optical coatings of hafnium oxide. Manufactured under stringent quality controls, this product is a dark grey, vacuum-sintered variant that exhibits a slight oxygen deficiency, resulting in a higher sintering density and improved electrical conductivity compared to air-sintered materials.

Designed specifically for advanced thin film deposition processes, this Hafnium (IV) Oxide UV Grey Granules material is perfectly suited for fabricating high-quality AR coatings, multilayer filters, mirrors, beam splitters, and laser components. Hafnia′s excellent durability, high refractive index, and scratch resistance enable the production of optical coatings that maintain superior performance across the UV, visible, and near infrared spectral regions. It is especially suitable for films with low absorption in the spectral region from 248 nm to 10 µm. Our Patinal® granules are uniquely vacuum-sintered to improve the electronic conductivity, which facilitates achieving higher density films and a higher refractive index. Rely on Patinal® to ensure process stability and reproducibility in sophisticated optical systems.

Hafnium oxide can only be evaporated by electron beam evaporation. For the deposition of homogeneous films with high density, elevated substrate temperatures are necessary. A further increase in density and a higher refractive index can be obtained by using an ion assisted deposition process (IAD). Thicker HfO2 layers tend to show a slight amount of refractive index inhomogenity by forming more crystalline fractions with growing film thickness. Prior to the deposition of the coatings, the material has to be premelted below a shutter using a sweeping electron beam to make sure a uniform melt surface is forming. In order to achieve the most stable process conditions, a stepwise filling of the crucible can be required to melt the material layer by layer. This will result in a properly outgassed and stable melt in the final coating process.

Patinal is a registered trademark of Merck KGaA, Darmstadt, Germany