Tomáš Křenek

Reactive deposition of laser ablated FeS1−x particles on a copper surface

Pulsed IR laser ablation of ferrous sulfide (FeS) in a vacuum has been studied using scanning and transmission electron microscopy and X-ray diffraction. This allows the analysis of the surface morphology and composition of the irradiated target and also of the coats deposited on unheated Ta, silica and Cu substrates. It is observed that a noncongruent ablation of FeS results in the deposition of nanosized FeS-containing FeS1−x amorphous coats on the silica and tantalum, and in the deposition of crystalline copper sulfide-containing amorphous Cu2S phases on copper. The detected amorphous Cu2S phase, crystalline and nanocrystalline chalcocite Cu2S, bornite Cu5FeS4, digenite Cu9S5 and blaubleibend covellite are formed through the reactive deposition of FeS1−x particles on the topmost Cu layers. This finding is the first example of the reactive deposition of laser ablated inorganic compounds on unheated surfaces and may spur more interest in using this simple process with various inorganic compounds to achieve reactive modifications of other materials.

Biomaterials and Nanotechnology Approach to Medical Enhancement

Over the past few decades, biomaterial science has emerged as a new field in which a regeneration or replacement of damaged tissue has become one of the main focuses. Also, great advances in the application of multifunctional nanoparticles for biomedical applications have been made. Implementation of nanomedicine in cellular, preclinical, and clinical studies has led to exciting advances ranging from fundamental to applied research. This chapter will examine the key aspects of application of traditional biomaterials, their physicochemical properties, and behavior in biological system. Moreover, the unique properties of nanomaterials are highlighted in relation to their vast nanostructural characteristics and the field of application. With 164 references.

Ceramic-like open-celled geopolymer foam as a porous substrate for water treatment catalyst

This paper presents results from experimental study on microstructural and mechanical properties of geopolymer-based foam filters. The process for making porous ceramic-like geopolymer body was experimentally established, consists of (a) geopolymer paste synthesis, (b) ceramic filler incorporation, (c) coating of open-celled polyurethane foam with geopolymer mixture, (d) rapid setting procedure, (e) thermal treatment. Geopolymer paste was based on potassium silicate solution n(SiO2)/n(K2O)=1.6 and powder mixture of calcined kaolin and precipitated silica. Various types of ceramic granular filler (alumina, calcined schistous clay and cordierite) were tested in relation to aggregate gradation design and particle size distribution. The small amplitude oscillatory rheometry in strain controlled regime 0.01% with angular frequency 10 rad/s was applied for determination of rheology behavior of prepared mixtures. Thermal treatment conditions were applied in the temperature range 1100 – 1300 °C. The developed porous ceramic-like foam effectively served as a substrate for highly active nanoparticles of selected Fe+2 spinels. Such new-type of nanocomposite was tested as a heterogeneous catalyst for technological process of advanced oxidative degradation of resistive antibiotics occurring in waste waters.

Optical emission spectroscopy of plasma produced by laser ablation of iron sulfide

Optical emission spectroscopy studies are reported of laser ablation plasma from an iron sulphide (FeS) target in vacuum. The plasma emission is characterized with spatial and tempoal resolution. The spectral observations are used to calculate the electron plasma parameters. The electron temperature is calculated by the Boltzmann plot method and the electron number density, by the Stark broadening of the emission lines.

Formation of Cu1-xGex Nanoplatelets Using LPCVD of Ge2Me6 or Ge2Me6/Et4Pb Mixture

Unlike synthesis of nanowires (1D nano-objects) the synthesis of nanoplatelets (2D nano-objects) has not been performed frequently. Herein, we report on the synthesis of Cu–Ge based on nanoplatelets with a high surface-to-volume ratio prepared by low pressure chemical vapor deposition (LPCVD) of Ge2Me6 and a mixture of Ge2Me6/PbEt4. Nanostructured deposits are composed of Cu1-xGex nanoplatelets, Ge nanowires and Ge nanoparticles. The nanoplatelets, which have the lateral size up to several tens of micrometers and thickness of 100–400 nm, belong to the cubic α phase of Cu91Ge9 alloy (Ge admixture in cubic Cu) and hexagonal ζ phase of Cu85Ge15 alloy. Nanowires composed of cubic Ge have a diameter of about 30 nm and length of several tens of micrometers. Lead does not enter any of these phases due to Pb–Cu and Pb–Ge immiscibility; therefore, it was observed as separate nanoparticles.