Skip to main content

Alex Dommann

University of Bern, ARTORG, Faculty Member

Swiss Federal Laboratories for Material Testing and Research, Materials meet Life, Faculty Member

Followers

175,977

Following

28

Co-authors

33

Mentions

1

Public Views

Alex Dommann was heading the Department «Materials meet Life» at Empa between 2013 and 2023. His research concentrates on the surface analysis, bio sur-face interactions, structuring, coating and characterization of thin films. He is member of different national and international committees and teaches Materials for Medtech, and Crystallography at different Swiss universities and has published more than 150 papers in the fields of thin films, coatings, Imaging, MEMS, reliability and material characterization. He is also member of the Swiss Academy of Engineering Science (SATW) and he is Emeritus at the University of Berne.
Phone: +41786027680
Address: Freiburgstrasse 3
CH-3010 Bern

less

InterestsView All (32)

Uploads

Papers by Alex Dommann

Correlated disorder by defects clusters in LiNbO 3 single crystals after crystal ion-slicing

by Simone Dolabella and Alex Dommann

Materials & Design, 2023

This work aims to understand the physics of the re-crystallization process of the CIS-damaged LNO... more This work aims to understand the physics of the re-crystallization process of the CIS-damaged LNO crystal upon thermal annealing. The study of the coherent and diffuse scattering by high-resolution X-ray diffraction, complemented by micro-Raman back-scattering spectroscopy and Transmission Electron Microscopy (TEM), allowed to study the recovery of the crystallinity from the CIS-induced lattice strain and stress and the progressive reduction of the defects clusters dimension.

Electromagnetic levitation containerless processing of metallic materials in microgravity: thermophysical properties

npj Microgravity

Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial ste... more Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial step in the industrial solidification of metallic alloy melts and are greatly influenced by the thermophysical properties of the melt. Knowledge of the thermophysical properties of liquid metallic alloys is necessary in order to gain a tight control over the solidification pathway, and over the obtained material structure of the solid. Measurements of thermophysical properties on ground are often difficult, or even impossible, since liquids are strongly influenced by earth’s gravity. Another problem is the reactivity of melts with container materials, especially at high temperature. Finally, deep undercooling, necessary to understand nucleus formation and equilibrium as well as non-equilibrium solidification, can only be achieved in a containerless environment. Containerless experiments in microgravity allow precise benchmark measurements of thermophysical properties. The electromagnetic le...

Diffusions barrier, an important layer for high temperature bonds

ABSTRACT Summary form only given. Sputtered Ta-Si-N films are investigated in view of their use a... more ABSTRACT Summary form only given. Sputtered Ta-Si-N films are investigated in view of their use as diffusion barriers. Deposition conditions and film properties such as atomic composition, crystallization temperature, surface roughness and, in particular, the amorphous structure as a function of the nitride concentration were analyzed by RBS, XRD and AFM. Their application as diffusion barriers in electromechanical microstructures and for interconnects with glass sealing are discussed

It's worth cleaning – The examination of the female taper could identify a particular cause of trunnionosis at revision 16 years after total hip arthroplasty

Journal of The Mechanical Behavior of Biomedical Materials, Mar 1, 2021

Adverse reaction to metal debris (ARMD) is an issue in metal-on-metal (MoM) total hip replacement... more Adverse reaction to metal debris (ARMD) is an issue in metal-on-metal (MoM) total hip replacements (THR). It mainly affects large-head MoM THR, whereas 28-32 mm MoM pairings are associated with low long-term revision rates. However, the bearing surface is not necessarily the only cause of metal debris. This report documents with advanced analysis of the retrievals a particular cause of trunnionosis in late failure of a small diameter MoM THR and illustrates the importance of cleaning of the taper when seating the head in THR. A 65year-old patient was revised due to ARMD 16 years after small diameter MoM THR. Debridement and exchange of the inlay and the head had been performed through an anterior approach. While the cup and the outer surface of the head were accessible to direct analysis by an optical coordinate measuring machine, the female taper had to be analysed indirectly by measuring an imprint. Wear from the cup and the head was within expected low ranges. The analysis of the female taper identified bone fragments, which contributed to trunnionosis. Failure due to ARMD after MoM THR is not necessarily caused by the bearing, but can be due to trunnionosis. Bone fragments within the taper contact in this case highlight the importance of meticulous cleaning of the taper before seating the head, to avoid trunnionosis.

New X-ray developments to characterize ceramic materials

Journal of Material Sciences & Engineering, Aug 9, 2016

Wet oxidation of Ti34Si23N43

Journal of Applied Physics, 1999

The wet oxidation of magnetron-sputtered x-ray-amorphous Ti34Si23N43 films at temperatures from 5... more The wet oxidation of magnetron-sputtered x-ray-amorphous Ti34Si23N43 films at temperatures from 500 to 1000 °C and ambient pressure was investigated by backscattering spectrometry, x-ray diffraction analysis, and step profilometry. Up to 800 °C, the oxidation yields x-ray-amorphous oxide scales of atomic composition Ti20Si13O67. At 500 and 550 °C the oxide growth kinetics is parabolic. At 700 and 800 °C, the oxidation kinetics is well described by a logarithmic time dependence. At 1000 °C, the oxide scale has a layered structure with a crystalline TiO2 layer on top of Ti–Si–O.

Thermophysical Properties of Bulk Metallic Glass Forming Alloys in the Stable and Undercooled Liquid — A Microgravity Investigation

MATERIALS TRANSACTIONS, 2001

Polarimetric imaging of the light backscattered from multiply scattering nanofibrous PVDFhfp scaffolds (Conference Presentation)

Epitaxial Si-Ge Heterostructures and Nanostructures for Optical and Electrical Applications

Micro-solid oxide fuel cells as power supply for small portable electronic equipment

Micro-solid oxide fuel cells running on reformed hydrocarbon fuels

Epitaxial self-assembly of 3-D semiconductor structures on deeply patterned Si substrates at the microscale

The formation of a homogeneous α-alumina coating on a Ni-based superalloy from a layer stack deposited by cathodic arc evaporation

Surface & Coatings Technology, Feb 1, 2019

Cathodic arc evaporation was applied to form a layer stack on a Ni-based superalloy single crysta... more Cathodic arc evaporation was applied to form a layer stack on a Ni-based superalloy single crystalline substrate in a single in-situ vacuum deposition process. The initial layer was deposited using a target with the same nominal composition as the superalloy substrate. Subsequently, a second layer was deposited using a target with a composition of 70 at.% Al and 30 at.% Cr, and the deposition was conducted in flowing oxygen to form Al-Cr-O. The thermal stability of the layer stack was investigated by means of a heat treatment at 1100°C in air. The substrate-like coating recrystallized at elevated temperature and showed epitaxial growth on the superalloy single crystal, according to transmission Kikuchi diffraction measurements. A thin layer of pure α-alumina formed on top of the substrate-like coating and a compact Al-Cr-O phase with corundum structure developed towards the top of the coating. Microstructural and chemical analyses of the coating architectures in the asdeposited and annealed states were performed by means of transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Rutherford backscattering spectrometry, and utilized to explain the recrystallization and diffusion processes in the layer stack.

その場酸化物形成の比較と陰極アーク蒸着により合成したNi‐アルミナイドの蒸着後高温酸化【Powered by NICT】

Surface & Coatings Technology, 2017

Divide et impera" in detector technology

A promising integrAtion strAtegy of pixelAted films on si by epitAxiAl self-Assembly

Electromagnetic levitation containerless processing of metallic materials in microgravity: thermophysical properties

NPJ microgravity, May 2, 2023

Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial ste... more Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial step in the industrial solidification of metallic alloy melts and are greatly influenced by the thermophysical properties of the melt. Knowledge of the thermophysical properties of liquid metallic alloys is necessary in order to gain a tight control over the solidification pathway, and over the obtained material structure of the solid. Measurements of thermophysical properties on ground are often difficult, or even impossible, since liquids are strongly influenced by earth's gravity. Another problem is the reactivity of melts with container materials, especially at high temperature. Finally, deep undercooling, necessary to understand nucleus formation and equilibrium as well as nonequilibrium solidification, can only be achieved in a containerless environment. Containerless experiments in microgravity allow precise benchmark measurements of thermophysical properties. The electromagnetic levitator ISS-EML on the International Space Station (ISS) offers perfect conditions for such experiments. This way, data for process simulations is obtained, and a deeper understanding of nucleation, crystal growth, microstructural evolution, and other details of the transformation from liquid to solid can be gained. Here, we address the scientific questions in detail, show highlights of recent achievements, and give an outlook on future work.

Synthesis and characterization of superalloy coatings by cathodic arc evaporation

Surface & Coatings Technology, Oct 1, 2017

Superalloy targets were produced from Ni-(Al-C-Co-Cr-Mo-Ta-Ti-W) powders by spark plasma sinterin... more Superalloy targets were produced from Ni-(Al-C-Co-Cr-Mo-Ta-Ti-W) powders by spark plasma sintering technology. The crystalline structure of the as-produced targets was investigated by XRD analysis and compared with the evolution of phases resulting from the operation of the cathodic arc at the target (cathode) surface. Coatings were synthesized at superalloy substrates utilizing these superalloy targets in non-reactive and reactive evaporation processes. Synthesized coatings and target surfaces were compared with respect to chemical composition and crystal structure. The interface between coating and superalloy substrates was investigated by TEM. As an example, a complete layer stack was synthesized by cathodic arc evaporation starting from the superalloy

Low-Energy Plasma Enhanced Chemical Vapor Deposition

MRS Proceedings, 1998

We discuss a new method for plasma enhanced chemical vapor deposition, applied to the epitaxial g... more We discuss a new method for plasma enhanced chemical vapor deposition, applied to the epitaxial growth of Si and of Si-Ge heterostructures. Growth rates up to 5 nm/s become possible at substrate temperatures below 6000 C, by utilizing very intense but low energy plasmas to crack the reactive gases, SiH 4 and GeH 4 , and to speed up the surface kinetics. The method is applied to the synthesis of step-graded Si-Ge buffer layers, exhibiting the well known cross-hatched surface morphology.

Correlated disorder by defects clusters in LiNbO3 single crystals after crystal ion-slicing

Materials & Design

This work aims to understand the physics of the re-crystallization process of the CIS-damaged LNO... more This work aims to understand the physics of the re-crystallization process of the CIS-damaged LNO crystal upon thermal annealing. The study of the coherent and diffuse scattering by high-resolution X-ray diffraction, complemented by micro-Raman back-scattering spectroscopy and Transmission Electron Microscopy (TEM), allowed to study the recovery of the crystallinity from the CIS-induced lattice strain and stress and the progressive reduction of the defects clusters dimension.

Nano-analytical characterization of endogenous minerals in healthy placental tissue: mineral distribution, composition and ultrastructure

The Analyst, 2019

This study reveals distinct characteristics of minerals formed during gestational ageing using na... more

Correlated disorder by defects clusters in LiNbO 3 single crystals after crystal ion-slicing

by Simone Dolabella and Alex Dommann

Materials & Design, 2023

This work aims to understand the physics of the re-crystallization process of the CIS-damaged LNO... more This work aims to understand the physics of the re-crystallization process of the CIS-damaged LNO crystal upon thermal annealing. The study of the coherent and diffuse scattering by high-resolution X-ray diffraction, complemented by micro-Raman back-scattering spectroscopy and Transmission Electron Microscopy (TEM), allowed to study the recovery of the crystallinity from the CIS-induced lattice strain and stress and the progressive reduction of the defects clusters dimension.

Electromagnetic levitation containerless processing of metallic materials in microgravity: thermophysical properties

npj Microgravity

Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial ste... more Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial step in the industrial solidification of metallic alloy melts and are greatly influenced by the thermophysical properties of the melt. Knowledge of the thermophysical properties of liquid metallic alloys is necessary in order to gain a tight control over the solidification pathway, and over the obtained material structure of the solid. Measurements of thermophysical properties on ground are often difficult, or even impossible, since liquids are strongly influenced by earth’s gravity. Another problem is the reactivity of melts with container materials, especially at high temperature. Finally, deep undercooling, necessary to understand nucleus formation and equilibrium as well as non-equilibrium solidification, can only be achieved in a containerless environment. Containerless experiments in microgravity allow precise benchmark measurements of thermophysical properties. The electromagnetic le...

Diffusions barrier, an important layer for high temperature bonds

ABSTRACT Summary form only given. Sputtered Ta-Si-N films are investigated in view of their use a... more ABSTRACT Summary form only given. Sputtered Ta-Si-N films are investigated in view of their use as diffusion barriers. Deposition conditions and film properties such as atomic composition, crystallization temperature, surface roughness and, in particular, the amorphous structure as a function of the nitride concentration were analyzed by RBS, XRD and AFM. Their application as diffusion barriers in electromechanical microstructures and for interconnects with glass sealing are discussed

It's worth cleaning – The examination of the female taper could identify a particular cause of trunnionosis at revision 16 years after total hip arthroplasty

Journal of The Mechanical Behavior of Biomedical Materials, Mar 1, 2021

Adverse reaction to metal debris (ARMD) is an issue in metal-on-metal (MoM) total hip replacement... more Adverse reaction to metal debris (ARMD) is an issue in metal-on-metal (MoM) total hip replacements (THR). It mainly affects large-head MoM THR, whereas 28-32 mm MoM pairings are associated with low long-term revision rates. However, the bearing surface is not necessarily the only cause of metal debris. This report documents with advanced analysis of the retrievals a particular cause of trunnionosis in late failure of a small diameter MoM THR and illustrates the importance of cleaning of the taper when seating the head in THR. A 65year-old patient was revised due to ARMD 16 years after small diameter MoM THR. Debridement and exchange of the inlay and the head had been performed through an anterior approach. While the cup and the outer surface of the head were accessible to direct analysis by an optical coordinate measuring machine, the female taper had to be analysed indirectly by measuring an imprint. Wear from the cup and the head was within expected low ranges. The analysis of the female taper identified bone fragments, which contributed to trunnionosis. Failure due to ARMD after MoM THR is not necessarily caused by the bearing, but can be due to trunnionosis. Bone fragments within the taper contact in this case highlight the importance of meticulous cleaning of the taper before seating the head, to avoid trunnionosis.

New X-ray developments to characterize ceramic materials

Journal of Material Sciences & Engineering, Aug 9, 2016

Wet oxidation of Ti34Si23N43

Journal of Applied Physics, 1999

The wet oxidation of magnetron-sputtered x-ray-amorphous Ti34Si23N43 films at temperatures from 5... more The wet oxidation of magnetron-sputtered x-ray-amorphous Ti34Si23N43 films at temperatures from 500 to 1000 °C and ambient pressure was investigated by backscattering spectrometry, x-ray diffraction analysis, and step profilometry. Up to 800 °C, the oxidation yields x-ray-amorphous oxide scales of atomic composition Ti20Si13O67. At 500 and 550 °C the oxide growth kinetics is parabolic. At 700 and 800 °C, the oxidation kinetics is well described by a logarithmic time dependence. At 1000 °C, the oxide scale has a layered structure with a crystalline TiO2 layer on top of Ti–Si–O.

Thermophysical Properties of Bulk Metallic Glass Forming Alloys in the Stable and Undercooled Liquid — A Microgravity Investigation

MATERIALS TRANSACTIONS, 2001

Polarimetric imaging of the light backscattered from multiply scattering nanofibrous PVDFhfp scaffolds (Conference Presentation)

Epitaxial Si-Ge Heterostructures and Nanostructures for Optical and Electrical Applications

Micro-solid oxide fuel cells as power supply for small portable electronic equipment

Micro-solid oxide fuel cells running on reformed hydrocarbon fuels

Epitaxial self-assembly of 3-D semiconductor structures on deeply patterned Si substrates at the microscale

The formation of a homogeneous α-alumina coating on a Ni-based superalloy from a layer stack deposited by cathodic arc evaporation

Surface & Coatings Technology, Feb 1, 2019

Cathodic arc evaporation was applied to form a layer stack on a Ni-based superalloy single crysta... more Cathodic arc evaporation was applied to form a layer stack on a Ni-based superalloy single crystalline substrate in a single in-situ vacuum deposition process. The initial layer was deposited using a target with the same nominal composition as the superalloy substrate. Subsequently, a second layer was deposited using a target with a composition of 70 at.% Al and 30 at.% Cr, and the deposition was conducted in flowing oxygen to form Al-Cr-O. The thermal stability of the layer stack was investigated by means of a heat treatment at 1100°C in air. The substrate-like coating recrystallized at elevated temperature and showed epitaxial growth on the superalloy single crystal, according to transmission Kikuchi diffraction measurements. A thin layer of pure α-alumina formed on top of the substrate-like coating and a compact Al-Cr-O phase with corundum structure developed towards the top of the coating. Microstructural and chemical analyses of the coating architectures in the asdeposited and annealed states were performed by means of transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Rutherford backscattering spectrometry, and utilized to explain the recrystallization and diffusion processes in the layer stack.

その場酸化物形成の比較と陰極アーク蒸着により合成したNi‐アルミナイドの蒸着後高温酸化【Powered by NICT】

Surface & Coatings Technology, 2017

Divide et impera" in detector technology

A promising integrAtion strAtegy of pixelAted films on si by epitAxiAl self-Assembly

Electromagnetic levitation containerless processing of metallic materials in microgravity: thermophysical properties

NPJ microgravity, May 2, 2023

Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial ste... more Transitions from the liquid to the solid state of matter are omnipresent. They form a crucial step in the industrial solidification of metallic alloy melts and are greatly influenced by the thermophysical properties of the melt. Knowledge of the thermophysical properties of liquid metallic alloys is necessary in order to gain a tight control over the solidification pathway, and over the obtained material structure of the solid. Measurements of thermophysical properties on ground are often difficult, or even impossible, since liquids are strongly influenced by earth's gravity. Another problem is the reactivity of melts with container materials, especially at high temperature. Finally, deep undercooling, necessary to understand nucleus formation and equilibrium as well as nonequilibrium solidification, can only be achieved in a containerless environment. Containerless experiments in microgravity allow precise benchmark measurements of thermophysical properties. The electromagnetic levitator ISS-EML on the International Space Station (ISS) offers perfect conditions for such experiments. This way, data for process simulations is obtained, and a deeper understanding of nucleation, crystal growth, microstructural evolution, and other details of the transformation from liquid to solid can be gained. Here, we address the scientific questions in detail, show highlights of recent achievements, and give an outlook on future work.

Synthesis and characterization of superalloy coatings by cathodic arc evaporation

Surface & Coatings Technology, Oct 1, 2017

Superalloy targets were produced from Ni-(Al-C-Co-Cr-Mo-Ta-Ti-W) powders by spark plasma sinterin... more Superalloy targets were produced from Ni-(Al-C-Co-Cr-Mo-Ta-Ti-W) powders by spark plasma sintering technology. The crystalline structure of the as-produced targets was investigated by XRD analysis and compared with the evolution of phases resulting from the operation of the cathodic arc at the target (cathode) surface. Coatings were synthesized at superalloy substrates utilizing these superalloy targets in non-reactive and reactive evaporation processes. Synthesized coatings and target surfaces were compared with respect to chemical composition and crystal structure. The interface between coating and superalloy substrates was investigated by TEM. As an example, a complete layer stack was synthesized by cathodic arc evaporation starting from the superalloy

Low-Energy Plasma Enhanced Chemical Vapor Deposition

MRS Proceedings, 1998

We discuss a new method for plasma enhanced chemical vapor deposition, applied to the epitaxial g... more We discuss a new method for plasma enhanced chemical vapor deposition, applied to the epitaxial growth of Si and of Si-Ge heterostructures. Growth rates up to 5 nm/s become possible at substrate temperatures below 6000 C, by utilizing very intense but low energy plasmas to crack the reactive gases, SiH 4 and GeH 4 , and to speed up the surface kinetics. The method is applied to the synthesis of step-graded Si-Ge buffer layers, exhibiting the well known cross-hatched surface morphology.

Correlated disorder by defects clusters in LiNbO3 single crystals after crystal ion-slicing

Materials & Design

This work aims to understand the physics of the re-crystallization process of the CIS-damaged LNO... more This work aims to understand the physics of the re-crystallization process of the CIS-damaged LNO crystal upon thermal annealing. The study of the coherent and diffuse scattering by high-resolution X-ray diffraction, complemented by micro-Raman back-scattering spectroscopy and Transmission Electron Microscopy (TEM), allowed to study the recovery of the crystallinity from the CIS-induced lattice strain and stress and the progressive reduction of the defects clusters dimension.

Nano-analytical characterization of endogenous minerals in healthy placental tissue: mineral distribution, composition and ultrastructure

The Analyst, 2019

This study reveals distinct characteristics of minerals formed during gestational ageing using na... more