Elżbieta Czerwosz

Investigation of Pd content in C–Pd films for hydrogen sensor applications

Nanocomposite carbonaceous-palladium (Nc-C-Pd) films were synthesized by physical vapor deposition method (PVD). Scanning electron microscopy studies showed that they were composed of carbonaceous matrix containing Pd nanograins. Nc-C-Pd films were also characterized by thermogravimetric analysis, X-ray powder diffraction, and Fourier transform infrared (FTIR) spectral analysis. The content of Pd in films synthesized at different PVD conditions was determined based on TG measurements. Technological parameters of PVD process affected C/Pd ratio. FTIR spectra exhibited characteristic absorption bands for the precursors of carbonaceous-palladium samples (fullerene C60 and palladium acetate). The influence of hydrogen on electrical properties of the films was tested by measuring their resistance in the presence of hydrogen (1% H2/N2).

Studies of structural changes in C60C70:Ni layers annealed under oxidative conditions

Abstract The structural changes in C 60 C 70 :Ni layers annealed at a temperature of 620 K were observed by Raman spectroscopy, electron diffraction, AFM and HRTEM methods. The ‘as grown’ C 60 C 70 :Ni layers exhibit the features of the amorphous structure, which is confirmed by broadened Raman bands of Hg(1) fullerene mode, diffused rings in the electron diffraction pattern (with 4.8 and 8.7 nm−1 radius) and HRTEM pictures. The AFM topographies depict grains of 100–200nm in size, rounded hillocks agglomerated in bigger ‘zigzag’ objects. The annealed layer contains two phases: amorphous and crystalline fcc C60 with enlarged lattice parameter (a = 1.44 nm). The changes toward crystalline structure are observed in Raman spectra (sharp Hg(1)mode) and in the electron diffraction pattern (reflexes (111), (220), (311), (420) and (422) of pure C60 fcc structure). The AFM topographies show two kinds of objects with different lateral sizes 300 and 100–200 nm and different base to top height 100–150 and 35 nm, respectively.

Tem and CL Investigations of Pd Nanograins Included in Carbonaceous Film

In this paper we presented results of investigation of carbonaceous-palladium materials obtained in the CVD (Chemical Vapor Deposition) process. This investigations were carried out with transmission electron microscopy (TEM) and scanning electron microscopy (SEM), equipped with spectrum imaging for cathodoluminescence (CL). The composites will be applied as a active layers in hydrogen and also hydrocarbons detectors. Our measurements showed that some of Pd nanoparticles have a graphite shell and also are optically active. This particle in CL spectrum reveal the peak wavelength around 525 nm (2,36 eV).

The Influence of Technological PVD Process Parameters on the Topography, Crystal and Molecular Structure of Nanocomposite Films Containing Palladium Nanograins

Abstract The paper describes the preparation and characteristics of films composed of Pd nanograins placed in carbonaceous matrix. Films were obtained in PVD (Physical Vapor Deposition) process from two sources containing: the first one - fullerene powder and the second one - palladium acetate. The topographical, morphological and structural changes due to different parameters of PVD process were studied with the use of Atomic Force Microscopy and Scanning Electron Microscopy, whereas the structure was studied with the application of the Transmission Electron Microscopy and Fourier Transform Infrared Spectroscopy methods. It was shown that topographical changes are connected with the decomposition ratio of Pd acetate as well as the form of carbonaceous matrix formed due to this decomposition. Palladium nanograins found in all films exhibit the fcc structure type and their diameter changes from 2 nm to 40 nm depending on the PVD process parameters.

Raman studies of Pd-C nanocomposites

The results of studying palladium-carbon (Pd-C) nanocomposites using Raman spectroscopy are presented. This method has been used for studying samples having various palladium content, prepared by a one-step Physical Vapour Deposition (PVD) process and a Chemical Vapour Deposition (two-step PVD/CVD) process using different process parameters. For samples obtained by PVD, the vibration bands characteristic of C60 fullerene molecules were observed in the spectra, whereas for layers obtained by PVD/CVD, the Raman spectra displayed mainly D and G bands characteristic solely of the prescence of graphite-like layers’ vibrations. The analysis of the obtained Raman spectra reveals that its shape is affected by many parameters including type of substrate, temperature, and the percentage content of Pd in the studied layer. The quantitative analysis of spectra for layers obtained using the PVD/CVD process shows a difference in the relative intensity of bands D and G, reflecting the different degrees of amorphisation in the investigated nanocomposites.

Infiuence of Hydrogen on the Properties of Nanostructured C-Pd Films for Sensing Applications

Abstract In this paper we present the results of the investigations of nanostructured C-Pd films for hydrogen sensing applications. These C-Pd films were prepared by physical vapor deposition and then annealed in an argon flow at the temperature of 500°C. The structure and morphology of the prepared C-Pd films were investigated using transmission electron microscopy and energy dispersive X-ray spectroscopy. We studied the infiuence of hydrogen on the electrical properties and crystal structure of C-Pd films. It was shown that film resistance changes depended on hydrogen concentration. At lower hydrogen concentration (up to 2 vol.%), the films response increased proportionally to [H2], while above 2 vol.% H2, it was almost constant. This is connected with the formation of a solid solution of hydrogen in palladium at lower H2 concentration and the creation of palladium hydride at higher H2 concentration. X-ray diffraction was used to confirm the formation of Pd-H solid solution and palladium hydride.

Women in technical universities in Poland

In this paper we present how the situation for Polish women in science has changed according to their age and scientific career level. More than 50% of students studying in all fields of sciences are women, but for math/physics/engineering studies there are fewer than 10% women. The numbers become better for PhD students in math/physics/engineering (34% women) at level of professor (about 25% women), but are still not nearly high enough.

The optical study of nanoporous C-Pd thin films

In this paper, the preliminary results for thin carbon-palladium (C-Pd) nanocomposites obtained by PVD/CVD method, carried out using optical methods are presented. Raman studies reveal the dominance of graphite-like structures. The optical transmittance measurement shows an exceptionally low value of the effective extinction coefficient when compared to amorphous graphite. The carbon structure porosity impact on the transmission properties of the studied layers is discussed.

Modelling of a Time Dependent Electron Diffusion Problem for Nanocrystalline One‐dimensional Carbon‐Palladium Structures via Homogenization

Analytical and numerical phenomena of the electron resistance in the time dependent electron flow in Pd nanocrys‐tals embedded in a carbonaceous matrix are studied. The asymptotic homogenization theory and Finite Element Method are applied to analyse and solve the problem.

Secondary electron microscopy and transmission electron microscopy studies of carbon nanotubes in C-Ni films

Carbon nanotubes films have been studied with SEM and TEM. The studied films were obtained using a two step method: PVD process and CVD process. Strongly defected and curled carbon nanotubes containing Ni nanoparticles formed the film with thickness of about 300–400 nm. Observed carbon nanotubes were of lengths from 100 nm to 300 nm and did not stick to each other.