Papers by Author: Miroslav Jelínek

Abstract: Thin films of Yb filled CoSb₃ were prepared on fused silica substrates using pulsed laser deposition method. The stoichiometric Yb_0.19Co₄Sb₁₂ target was prepared by hot pressing method. The deposition conditions were changed with the goal to reach layers of smooth morphology. The target-to substrate distance was kept equal to 4 cm. The ambient argon pressure moved from 0.5 Pa to 13 Pa, laser repetition rate from 3 Hz to 10 Hz, and substrate temperature from 250 °C to 400 °C. We tested laser fluencies from 0.8 J·cm^-2 to 5 J·cm^-2. Films roughness was determined by mechanical profilometer and by atomic force microscopy. The lowest roughness of about 5 nm – 10 nm was reached for low laser fluencies but mechanical quality of films was poor and growth rate low (about 0.1 A/pulse). From WDX analysis follows that there is an excess of Yb and Sb compared to Yb_0.19Co₄Sb₁₂ target.

Abstract: Textile vascular prostheses ARTECOR were coated by laser with amorphous diamond-like carbon layers (DLC) with thickness up to 200 nm. Layers were created in 0.25 Pa of Argon at laser energy density of 8 or 22 Jcm-2. Depending on the deposition conditions, DLC properties moved from soft „graphitic“ to more „diamond“ (53 % of sp3 bonds). Coated prostheses of various DLC thickness and sp3 content were implanted into carotid artery of Merino sheep. The prostheses were extirpated after 100 days (~180 days). From preliminary results follows that prostheses coated with DLC layer thickness of 20 nm and higher sp3 content showed the best results.

Abstract: Nanocrystalline diamond (NCD) films have been prepared by microwave plasma chemical vapor deposition (MWCVD) from methane/nitrogen mixtures, and the influence of the gas phase composition on the basic properties of the films (composition, morphology, topography, crystallinity and bonding structure) was investigated.