Nachrichtendetails

Vorträge: Pulsed Laser Deposition und Nanostructured Multilayers

Vorträge im Fakultätskolloquium am 13.9.2007


Im Rahmen des Fakultätskolloquiums finden am
Donnerstag, dem 13.9.2007, um 15 Uhr h.c.t., im Seminarraum des Instituts für Phys. Chemie, 2. OG, Arnold-Sommerfeld-Str. 4,
folgende Gastvorträge statt:

Pulsed Laser Deposition: from basic principles to most recent developments
Prof. Dr. Ion N. Mihailescu, National Institute for Lasers, Plasma & Radiation Physics, Bucharest-Magurele, Romania

Nanostructured multilayers synthesized by pulsed laser technologies for biomedical and gas sensing applications
Dr. Carmen Ristoscu, National Institute for Lasers, Plasma & Radiation Physics, Bucharest-Magurele, Romania

Pulsed Laser Deposition: from basic principles to most recent developments
Pulsed laser deposition (PLD) has recently emerged as a novel technique for synthesizing high-quality nanostructured coatings for applications in key technological fields. We review in this lecture the general elements and operation characteristics of present day PLD installations. We emphasize upon the main physical phenomena involved, such as the role of the ambient gas and plasma in the deposition process, the relation between the ablation parameters and the plasma expansion, and the overall deposition efficiency. One major advantage of PLD is the deposition of highly uniform, very adherent thin films. However, the main shortcoming remains the presence on films surfaces and inside their volume of particulates with various shapes and dimensions. We demonstrated that the formation of these particulates depends on the specific irradiation conditions, target and/or ambient gas nature and pressure. The experimental conditions required for the decreasing of the particulates density or for their complete elimination can be optimized in every particular case only.
Over the past few years, PLD has been combined with cryogenic procedures to extend its application range to compounds which usually are very sensitive to temperature decomposition and damage. The new methods called Matrix Assisted Pulsed Laser Evaporation (MAPLE) and Direct Write Matrix Assisted Pulsed Laser Evaporation (MAPLE DW) differ from PLD in target preparation and interaction mechanisms. The typical experimental setup-ups and operation modes will be presented.

Nanostructured multilayers synthesized by pulsed laser technologies for biomedical and gas sensing applications
We review recent developments in Pulsed Laser Deposition (PLD) and Matrix Assisted Pulsed Laser Evaporation (MAPLE) which made possible to deposit high-quality stoichiometric and adherent nanostructured coatings of Ca phosphates (CaPs), polymers, and metal oxide films.
I. Targets prepared from powders had been used from the following CaPs: Hydroxylapatite (HAP - Ca10(PO4)6(OH)2), octacalcium phosphate (OCP - Ca8(HPO4)2(PO4)4·5H2O), manganese doped and carbonated hydroxylapatite (Mn:CHA) and tricalcium phosphate (TCP - Ca3(PO4)2). The depositions were performed with a KrF* (248 nm, 7.4 ns) laser in low pressure (10 - 50 Pa) oxygen or water vapors on substrates made of grade-4 etched Ti heated to 400 C. A post-deposition treatment in water vapor enriched atmosphere was applied for 6h at 400 C.
MAPLE was used to deposit hybrid inorganic-organic nanocomposite layers of CaPs and polymers. A stoichiometric transfer of the hybrid nanocomposite (polymer + HAP) was demonstrated.
Functionality of obtained biomimetic implants have been proved by in vitro (cell morphology, proliferation and viability, cytoskeleton labeling, alkaline phosphatase activity, collagen type 1, transforming growth factor beta 1) and in vivo (pull out) tests.
II. We synthesize new highly transparent, thin metal oxide films (ZnO, TiO2, WO3) for nanostructured photonic gas sensors. All depositions were highly (up to 90%) transparent. M-line and Mach-Zehnder interferometers (ensuring detection of refractive index variations of ?n ? 10-4) were used to prove that under optimum processing conditions, the obtained nanostructures were able to detect hydrocarbons (butane, propane) traces down to 100 ppm.
Developed systems have been redesigned and miniaturized to build up a small prototype for fast detection of gas traces in ambient atmosphere.









Nachrichtenalter: 13.08.2007 09:20
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