Low-temperature ion beam sputtered optical coatings

In thin film deposition processes, the lower limit of the deposition temperature is determined by the used coating technology and the duration of the coating process and is usually higher than room temperature. Hence, the processing of thermally sensitive materials and the adjustability of thin film morphology are limited. In consequence, for factual low-temperature deposition processes, an active cooling of the substrate is required. The effect of low substrate temperature on thin film properties during ion beam sputtering was investigated. The S i O ₂ and T a ₂ O ₅ films grown at 0°C show a trend of lower optical losses and higher laser induced damage threshold (LIDT) compared to 100°C.

Crystallization of HfO2 thin films and their influence on laser induced damage

We present our investigation on the crystallization of IBS HfO2 on (0001) SiO2. The crystallization was studied by in-situ XRD. The activation energy was 2.6±0.5 eV. The growth follows a two-dimensional mode. LIDT measurements (5000-on-1) with 10 ns pulses at 355 nm on 3QWT HfO2 layers shows that the crystallization leads to increase of the laser irradiation resistance. The 0%-LIDT of the as coated sample was 3.1 J/cm2 and increased to 3.7 J/cm2 after 5h @ 500°C.

The chemical-free production of nanocelluloses from microcrystalline cellulose and their use as Pickering emulsion stabilizer

This paper takes a comparative approach in characterizing two types of nano-scale cellulosic particles obtained using chemical-free pathways, either by nearcritical water treatment or by high-shear homogenization from the same microcrystalline cellulose (MCC). The nearcritical water treatment efficiently depolymerized cellulose, producing a solid precipitated fraction of low-molecular-weight material containing cellulose II, while homogenization mechanically deconstructed MCC without altering its molecular structure. Both pathways yielded nanocellulose-like materials yet with different morphologies. The mechanically produced, rod-like particles were obtained with high yield. In contrast, the hydrothermal precipitate exhibited more hydrophobic ribbon-like particles that provided a greater level of particle-particle interaction. Both materials successfully acted as stabilizers for oil-in-water Pickering emulsions; however, the hydrothermally-produced material exhibited superior performance, with stable emulsions obtained upon addition of as low as 1.0wt.% cellulose. These two pathways are highly relevant for altering the structure and properties of MCC and for formulating new, sustainably produced nanocellulose-based materials.