SCHUT , Henk

Results of positron annihilation measurements on NaY pressed powders and deposited thin films using slow positron beam and conventional fast positron techniques are presented. In lifetime experiments using an external 22Na source an averaged long lifetime of 1.8 ns with a sum intensity of 27% was observed in pressed powders in the presence of...

A modified blister test has been developed based on helium ion implantation into selected areas of the metal substrate prior to the coating deposition. After a post-deposition thermal annealing, blisters are formed by agglomeration of the implanted gas at the ceramic–metal interface. This method can be used to control the pressure in the...

Surface effects on (1 1 1) copper single crystal surfaces after 30 keV helium implantation up to 2.4 × 1016 ions cm−2 and subsequent annealing at 973 K have been studied using scanning electron and confocal microscopy. Since one aim of the work was to develop a method of studying the adhesion of surface coatings, the implantations were...

Positron annihilation spectroscopy (PAS) has proven to be a very useful technique for, e.g., the study of defects in materials and the characterization of polymer free-volume. Positron lifetime, Doppler broadening of the annihilation radiation (characterized by the so-called S parameter) and angular correlation of annihilation radiation (ACAR)...

Positron beam analysis (PBA) and transmission electron microscopy (TEM) were applied to study structural transformations in cold-rolled Fe0.94Ni0.04Ti0.02 foils, which were subjected to different thermal treatments in an atmosphere of a gas mixture of NH3 + H2 (nitriding). Positrons proved to be sensitive probes for the microstructure evolution...

Thin coatings of poly-ethylene terephthalate (PET) on metal ("laminates") have been studied with a variable energy positron annihilation technique. A correlation between PET crystallinity and the positron annihilation parameter S related to the free volume in the polymer is found. It is shown that buried interfaces in these systems may be...

In this work we have studied the adhesion of PVD amorphous hydrogenated carbon (a-C:H) thin coatings (<200 nm) on crystalline silicon by means of positron beam analysis (PBA). PBA allows the study of the a-C:H layer and the interface by monitoring changes on the Doppler broadening parameters S and W. Depending on the deposition condition, using...

An electrostatic variable energy positron beam for studying defects in ceramic coatings, polymer films and MOS-devices is developed for operation in Doppler-broadening (DB) and positron annihilation lifetime (PAL) modes. In DB mode the implantation energy can be varied between 3 and 30 keV with a beam diameter on the target ranging from 0.4 to...

In this paper we present the first combined Positron Beam Analysis (PBA) and Environmental Scanning Electron Microscopy (ESEM) adhesion study on thin chromium nitride (CrNx) coatings. Both techniques are combined with a 4-point bending stage. PBA monitors the creation of open volume in the ceramic/metal interface prior to delamination while...

Two sets of ZrO2 thin films have been prepared at room temperature by ion beam induced chemical vapour deposition and subsequently annealed up to 1323 K. The two sets of samples have been prepared by using either O2+ or mixtures of (O2++Ar+) ions for the decomposition of a volatile metallorganic precursor of zirconium. The structure and...

An overview is given of the extension of the Delft variable energy positron (VEP) beam facility with equipment for in situ heating, cooling, 4-point bending, hydrogen permeation and gas ad- and absorption of bulk materials, surfaces and interfaces.

Intrinsic stress in amorphous hydrogenated carbon (a-C:H) coatings was reduced through addition of 10–20 sccm N2 to the feed gas. The compressive stresses observed in this study were in the range −0.91 to −1.6 GPa. Approximately 2–3 at.% nitrogen was incorporated into the coatings as determined using elastic recoil detection (ERD). Raman...

Non-destructive Doppler Broadening (DB), Positronium fraction (f-Ps) and Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR), Positron Beam Analysis (PBA) techniques have been used to study well-ordered mesoporous silica thin films with hydrophobic or hydrophilic character. The DB results, characterized by the S and W...

Positron beam techniques have been employed to characterise low-k dielectric silica based films, which have two or three dimensional structures of nanometre size pores. Pore fractions vary from 5 to 50%. Positrons implanted in the layer slow down and eventually annihilate with the electrons from the layer. However, in pores of the dielectric...

Depth-selective 2D-ACAR investigations on ordered mesoporous silica thin films provide direct evidence that para-positronium (p-Ps) created deep in the films can escape through a network of interconnected pores. The depth dependence of the escape fraction and of the average kinetic energy of non-thermally excited p-Ps is in quantitative...

The porosity in particle reinforced sol-gel coatings has been studied. Silica particles (Ludox-TM40) are introduced into methyl silicate coatings to increase the hardness, the elastic modulus and the fracture toughness. The methyl silicate has a relatively low density (about 1.2 g/cm2), while the silica particles are known to be porous....