@article{65270, abstract = {{In perovskite solar cells (PSCs), electron transport layers (ETLs) play an important role in the selection and transport of electrons. Understanding the properties of these layers in relation to device performance is essential for optimizing solar cell efficiency and enabling their integration into emerging architectures, such as flexible solar cells. Here, we deposited TiO2 at different thicknesses using atomic layer deposition (ALD), a technique well-suited for producing uniform and pinhole-free films. The crystal structure of the layers was controlled by depositing the films at three different temperatures: 150 °C, 250 °C, and 350 °C. The layers were characterized in detail to determine the morphology (by atomic force microscopy), surface composition (by X-ray photoelectron spectroscopy) and the crystal structure (by X-ray diffraction). The TiO2 layers were then incorporated as ETLs in planar perovskite solar cells to evaluate their influence on device performance. Higher deposition temperatures led to improvements in device fill factor and open-circuit voltage, leading to more efficient solar cells. Notably, the best device performance for the ALD-TiO2 layers was achieved with films deposited at 250 °C.}}, author = {{Qudsia, Syeda and Weiss, Alexander and Sirkiä, Saara and Wang, Fuzeng and Rosqvist, Emil and Los Arcos, Teresa De and Weinberger, Christian and Halme, Janne and Kemell, Marianna and Smått, Jan-Henrik}}, issn = {{0169-4332}}, journal = {{Applied Surface Science}}, keywords = {{Titanium dioxide, Atomic layer deposition, Electron transport layer, Perovskite solar cells}}, pages = {{166755}}, title = {{{Influence of deposition temperature and thickness of ALD-TiO2 on planar perovskite solar cell performance}}}, doi = {{https://doi.org/10.1016/j.apsusc.2026.166755}}, year = {{2026}}, } @article{63072, abstract = {{Titanium alloys are widely employed for biomedical implants due to their high strength, biocompatibility, and corrosion resistance, yet their lack of intrinsic antibacterial activity remains a major limitation. Incorporating copper, an antibacterial and β-stabilising element, offers a promising strategy to enhance implant performance. This study investigates Ti-6Al-7Nb modified with 1–9 wt.% Cu via in situ alloying during metal-based laser powder bed fusion (PBF-LB/M), with the aim of assessing processability, microstructural evolution, and mechanical properties. Highly dense samples (>99.9%) were produced across all Cu levels, though chemical homogeneity strongly depended on processing parameters. Increasing Cu content promoted β-phase stabilisation, Ti2Cu precipitation, and pronounced grain refinement. Hardness and yield strength increased nearly linearly with Cu addition, while ductility decreased sharply at ≥5 wt.% Cu due to intermetallic formation, hot cracking, and brittle fracture. These results illustrate both the opportunities and constraints of rapid alloy screening via PBF-LB/M. Overall, moderate Cu additions of 1–3 wt.% provide the most favourable balance between mechanical performance, manufacturability, and potential antibacterial functionality. These findings provide a clear guideline for the design of Cu-functionalised titanium implants and demonstrate the efficiency of in situ alloy screening for accelerated materials development.}}, author = {{Steinmeier, Paul and Hoyer, Kay-Peter and Lopes Dias, Nelson Filipe and Zielke, Reiner and Tillmann, Wolfgang and Schaper, Mirko}}, issn = {{2073-4352}}, journal = {{Crystals}}, keywords = {{Biomaterial, In Situ Alloying, Titanium, Additive Manufacturing}}, number = {{12}}, publisher = {{MDPI AG}}, title = {{{In Situ Alloying of Ti-6Al-7Nb with Copper Using Laser Powder Bed Fusion}}}, doi = {{10.3390/cryst15121053}}, volume = {{15}}, year = {{2025}}, } @article{29196, abstract = {{In biomedical engineering, laser powder bed fusion is an advanced manufacturing technology, which enables, for example, the production of patient-customized implants with complex geometries. Ti-6Al-7Nb shows promising improvements, especially regarding biocompatibility, compared with other titanium alloys. The biocompatible features are investigated employing cytocompatibility and antibacterial examinations on Al2O3-blasted and untreated surfaces. The mechanical properties of additively manufactured Ti-6Al-7Nb are evaluated in as-built and heat-treated conditions. Recrystallization annealing (925 °C for 4 h), β annealing (1050 °C for 2 h), as well as stress relieving (600 °C for 4 h) are applied. For microstructural investigation, scanning and transmission electron microscopy are performed. The different microstructures and the mechanical properties are compared. Mechanical behavior is determined based on quasi-static tensile tests and strain-controlled low cycle fatigue tests with total strain amplitudes εA of 0.35%, 0.5%, and 0.8%. The as-built and stress-relieved conditions meet the mechanical demands for the tensile properties of the international standard ISO 5832-11. Based on the Coffin–Manson–Basquin relation, fatigue strength and ductility coefficients, as well as exponents, are determined to examine fatigue life for the different conditions. The stress-relieved condition exhibits, overall, the best properties regarding monotonic tensile and cyclic fatigue behavior.}}, author = {{Hein, Maxwell and Kokalj, David and Lopes Dias, Nelson Filipe and Stangier, Dominic and Oltmanns, Hilke and Pramanik, Sudipta and Kietzmann, Manfred and Hoyer, Kay-Peter and Meißner, Jessica and Tillmann, Wolfgang and Schaper, Mirko}}, issn = {{2075-4701}}, journal = {{Metals}}, keywords = {{General Materials Science, Metals and Alloys, laser powder bed fusion, Ti-6Al-7Nb, titanium alloy, biomedical engineering, low cycle fatigue, microstructure, nanostructure}}, number = {{1}}, publisher = {{MDPI AG}}, title = {{{Low Cycle Fatigue Performance of Additively Processed and Heat-Treated Ti-6Al-7Nb Alloy for Biomedical Applications}}}, doi = {{10.3390/met12010122}}, volume = {{12}}, year = {{2022}}, } @article{28017, abstract = {{Processing aluminum alloys employing powder bed fusion of metals (PBF-LB/M) is becoming more attractive for the industry, especially if lightweight applications are needed. Unfortunately, high-strength aluminum alloys such as AA7075 are prone to hot cracking during PBF-LB/M, as well as welding. Both a large solidification range promoted by the alloying elements zinc and copper and a high thermal gradient accompanied with the manufacturing process conditions lead to or favor hot cracking. In the present study, a simple method for modifying the powder surface with titanium carbide nanoparticles (NPs) as a nucleating agent is aimed. The effect on the microstructure with different amounts of the nucleating agent is shown. For the aluminum alloy 7075 with 2.5 ma% titanium carbide nanoparticles, manufactured via PBF-LB/M, crack-free samples with a refined microstructure having no discernible melt pool boundaries and columnar grains are observed. After using a two-step ageing heat treatment, ultimate tensile strengths up to 465 MPa and an 8.9% elongation at break are achieved. Furthermore, it is demonstrated that not all nanoparticles used remain in the melt pool during PBF-LB/M.}}, author = {{Heiland, Steffen and Milkereit, Benjamin and Hoyer, Kay-Peter and Zhuravlev, Evgeny and Keßler, Olaf and Schaper, Mirko}}, journal = {{Materials}}, keywords = {{grain refinement, crack reduction, laser beam melting, aluminum alloy, titanium carbide, nanoparticle, PBF-LB/M}}, title = {{{Requirements for Processing High-Strength AlZnMgCu Alloys with PBF-LB/M to Achieve Crack-Free and Dense Parts}}}, doi = {{https://doi.org/10.3390/ma14237190}}, year = {{2021}}, } @article{24086, abstract = {{Laser beam melting (LBM) is an advanced manufacturing technology providing special features and the possibility to produce complex and individual parts directly from a CAD model. TiAl6V4 is the most common used titanium alloy particularly in biomedical applications. TiAl6Nb7 shows promising improvements especially regarding biocompatible properties due to the substitution of the hazardous vanadium. This work focuses on the examination of laser beam melted TiAl6Nb7. For microstructural investigation scanning electron microscopy including energydispersive x-ray spectroscopy as well as electron backscatter diffraction are utilized. The laser beam melted related acicular microstructure as well as the corresponding mechanical properties, which are determined by hardness measurements and tensile tests, are investigated. The laser beam melted alloy meets, except of breaking elongation A, the mechanical demands like ultimate tensile strength Rm, yield strength Rp0.2, Vickers hardness HV of international standard ISO 5832-11. Next steps contain comparison between TiAl6Nb7 and TiAl6V4 in different conditions. Further investigations aim at improving mechanical properties of TiAl6Nb7 by heat treatments and assessment of their influence on the microstructure as well as examination regarding the corrosive behavior in human bodylike conditions.}}, author = {{Hein, Maxwell and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{0933-5137}}, journal = {{Materialwissenschaft und Werkstofftechnik}}, keywords = {{Laser beam melting, titanium alloy, TiAl6Nb7, biomedical engineering, implants}}, pages = {{703--716}}, title = {{{Additively processed TiAl6Nb7 alloy for biomedical applications}}}, doi = {{10.1002/mawe.202000288}}, volume = {{52}}, year = {{2021}}, }