Advanced Materials Letters

A microplasma electrode was used for skin treatment using argon, oxygen, nitrogen or ambient air. The presence of various particles is important for the interpretation of the microplasma effect on the skin. The production of long living particles was detected by an FTIR spectrometer and the presence of air between the sample and the electrode was monitored by the O2 monitor. In the case of gases other than air, we concluded that the concentration of processing gas is at least 99.5 %. The epidermal layer of pig skin was used for observing changes caused by microplasma treatment. The XPS spectra of carbon and oxygen were analysed.

Due to its biocompatibility poly(dimethylsiloxane) (PDMS) is an important material for the development of microelectromechanical systems or long-term, medical implants. The paper describes the morphology modifications and surface chemistry of PDMS during pulse laser treatment. SEM, μ-Raman spectroscopy, X-ray micro-tomography and XPS analyses are applied. PDMS decomposition takes place as a function of laser energy absorption. This leads to different oxidation degree of silicon, as shown by the curve fitting of Si 2p and O 1s. The irradiated parts become hydrophilic in contrast with the rest of the material, which remains hydrophobic. This is the condition enabling successful selective electroless deposition of Ni in the tracks, excluding the usual preceding sensibilization and chemical activation. This process is accomplished successfully after femtosecond laser irradiation and it is found that the time interval between laser treatment and metallization is not a critical parameter.

ZrO2 and HfO2 powder samples were prepared by using the chemical precipitation method and subsequent annealing. Crystal structure, local electronic structure and dielectric constant of amorphous and crystalline powders of ZrO2 and HfO2 have been examined using the synchrotron X-ray diffraction, O K-edge X-ray absorption spectroscopy, Zr 3d and Hf 4f core-level X-ray photoelectron spectroscopy and temperature dependent dielectric measurements, respectively. Amorphous ZrO2 and HfO2 powders exhibit a local tetragonal structure, with mixed +3 and +4 valence states of Zr and Hf ions, and demonstrated the high dielectric performance. After the heat treatment, the tetragonal phase transforms into the monoclinic phase with dominant +4 valence state of Zr and Hf ions and the larger sized ZrO2 and HfO2 nanoparticles exhibited low dielectric constant. The manifestation of high dielectric constants in the amorphous ZrO2 and HfO2 samples is because of the hopping of electrons between the Zr +3 -Zr +4 and Hf +3 -Hf +4 networks. 

Triangular nano-scale pits (TNPs) of Si3N4 are fabricated by reactive nitrogen ion sputtering using low energy nitrogen ions on the Si (553) surface at 500 °C. The electronic structure of the developing Si3N4 interface was monitored in-situ by Auger Electron Spectroscopy (AES) while the ion beam induced surface reaction was analysed via X-Ray and Ultraviolet photoemission spectroscopy (XPS & UPS), Photoluminescence and Raman spectroscopy. The morphological development of nanoscale pit structures was observed by Scanning Electron Microscopy (SEM). The formation of Si3N4 was identified by AES, with the appearance of the characteristic reacted Si(LVV) peak at 83 eV, while photoemission spectroscopy confirmed the stoichiometry of Si3N4. The valence band maximum was observed to be located at 2.4 eV below the Fermi level.  SEM images showed uniformly distributed Si3N4 TNPs with size varying between 250 to 600 nm (length) and 200 to 400 nm (width). Our work underlines the influence of ion energy and substrate temperature and establishes the conditions for the growth of Si3N3 TNPs by ion induced reactive sputtering.

In this letter, the thermoluminescence response and surface properties of Sr3B2O6:Dy 3+ nanophosphor prepared by combustion method exposed to γ–rays are reported. The crystalline structure of nanophosphors was confirmed by X-ray powder diffraction. The result indicates rhombohedral nanocrystalline structure with an average grain size of 41 nm. The microstructure and morphology were studied by transmission electron microscopy, which show nanowire like structure with an average diameter of 42 nm. The samples were irradiated with a γ-dose using 60Co source in the range of 100 Gy - 5000 Gy. The kinetic parameter such as activation energy (E), order of kinetics (b), and frequency factor (s) of the main glow peaks of the Sr3B2O6:Dy 3+ sample at 5000 Gy and different heating rates were determined using both the TLAnal program and Chen’s method. The effect of different heating rate at a fixed dose is discussed. X-ray photoelectron spectroscopy was used to study the surface chemical composition and the electronic states.

We have studied the adsorption of two silane compounds, (3-mercaptopropyl) trimethoxysilane (MPTMS) and n-propyltriethoxysilane (PTES), on a rutile TiO2(110) surface using angle dependent X-ray photoelectron spectroscopy. The observation of the S 2p line, in the case of MPTMS, and the C 1s line for both MPTMS and PTES confirms the adsorption of the molecules. For a dose of 122 Langmuirs of MPTMS we find room temperature coverage of 0.55 monolayers, while for a 60 Langmuir dose of PTES the coverage is found to be 0.89 monolayers. Thus, MPTMS has a considerably lower sticking coefficient on the rutile TiO2(110) surface than PTES. Both PTES and MPTES are found to bind dissociatively to the surface. An analysis of angle dependent data further suggests that for MPTMS the thiol group and thus alkyl chain points away from the surface, while for a 0.5 monolayer coverage of PTES the alkyl chain is oriented towards the surface. A higher coverage, ~1 monolayer, the behavior seems to be reversed for at least a fraction of all molecules. Temperature programmed XPS measurements suggest that the oxy groups of both molecules desorb from the surface at 550 K, which is in accordance with literature. The present study thus provides information on how these silane coupling agents bind to titanium oxide and what their molecular orientation is on the surface.