Article
Chemistry, Physical
Mira Simmler, Manuel Meier, Hermann Nirschl
Summary: This work investigates the complex particle structures made by spray flame synthesis. The influence of precursor concentration on the fractal structures of zirconia nanoparticles is analyzed using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The results show that unstable process conditions are identified at low precursor concentrations, resulting in a broad size distribution of primary particles with rough surfaces. Higher precursor concentrations lead to reproducible primary particle sizes almost independent of the initial precursor concentration. In addition, the typical shape of aggregates for aerosols is present for the investigated range of precursor concentrations.
Article
Nanoscience & Nanotechnology
Ali El Boutaybi, Thomas Maroutian, Ludovic Largeau, Nathaniel Findling, Jean-Blaise Brubach, Rebecca Cervasio, Alban Degezelle, Sylvia Matzen, Laurent Vivien, Pascale Roy, Panagiotis Karamanis, Michel Rerat, Philippe Lecoeur
Summary: The crystal structure and ferroelectric properties of ZrO2 films with thickness ranging from 7 to 42 nm grown on (110)-oriented SrTiO3 substrate with La0.67Sr0.33MnO3 buffer layer are reported. It is confirmed that the films have a tetragonal phase structure and exhibit ferroelectric behavior at thinner thicknesses, but the ferroelectricity diminishes with increasing film thickness.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Xuemei Song, Yi Ding, Jimei Zhang, Caifen Jiang, Ziwei Liu, Chucheng Lin, Wei Zheng, Yi Zeng
Summary: This study investigates the effect of phase composition and microstructure on the thermophysical and mechanical properties of Yttrium-stabilized zirconia (YSZ) materials. The results show that YSZ materials with cubic (c-YSZ) phase are more suitable as thermal barrier coatings (TBCs) due to their superior heat insulation, thermal expansion match, and strain tolerance. The c-YSZ phase also has lower thermal conductivity and greater lattice distortion, oxygen vacancies, and sound velocity due to Y2O3 doping. Additionally, the c-YSZ phase exhibits lower elastic modulus, better malleability and plasticity, while the tetragonal (t-YSZ) phase has better fracture toughness.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Chemistry, Inorganic & Nuclear
Feng Zhao, Shuangde Li, Yunfa Chen
Summary: The Ce-Zr oxide solid solution with different Zr dopants can significantly enhance oxygen storage capacity and thermal stability. Ethanol addition to the carboxylic acid solvent further increases oxygen vacancy concentration and improves oxygen storage capacity. Introducing ethanol can suppress Zr migration from the lattice to the surface of CeO2 at 1000 degrees C, enhancing oxygen storage capacity and thermal stability.
JOURNAL OF SOLID STATE CHEMISTRY
(2021)
Article
Chemistry, Physical
Xuefeng Liu, Quan Zhang, Jianmin Liu, Tao Wang, Yanqiao Xu, Jian Liang, Feng Jiang, Guo Feng, Weihui Jiang
Summary: By utilizing CaF2 as a stabilizer and adsorbent in molten salt processing, tetragonal zirconia whiskers with a desired morphology can be synthesized, showing single crystalline nature and a specific aspect ratio.
JOURNAL OF MATERIOMICS
(2021)
Article
Materials Science, Multidisciplinary
Edward L. Pang, Gregory B. Olson, Christopher A. Schuh
Summary: The study systematically investigates the thermal hysteresis in ZrO2-CeO2 shape-memory ceramics, revealing the impact of CeO2 content on hysteresis through calorimetry measurements and in situ X-ray diffraction analysis. The findings provide insights into the controlling factors of hysteresis in SMCs and clarify previous contradictory reports in the literature.
Article
Physics, Applied
Hiroshi Masuda, Daiki Tamao, Hidehiro Yoshida
Summary: Recent experiments have reported the effects of external electric fields on phonon-associated phenomena in ZrO2 ceramics, such as phase transformation and diffusion. This study used density-functional perturbation theory to examine the effects of external direct current (DC) electric fields on phonon vibration properties in a tetragonal ZrO2 unit cell. The results showed that the field sensitivities of phonon characteristics exhibited significant orientation dependence, and optical phonons showed considerable field sensitivities near the Brillouin zone boundaries. In contrast, transversal acoustic phonons demonstrated a softening trend with increasing field strengths, indicating the potential phase transformation under strong external electric fields.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Loukas Belles, Constantinos Moularas, Szymon Smykala, Yiannis Deligiannakis
Summary: The study successfully synthesized Co3O4 and CoO/Co3O4 nanostructures as electrocatalysts for ORR, achieving efficient ORR performance under low-Pt loading conditions.
Article
Nanoscience & Nanotechnology
Martin T. Matter, Leonida Maliqi, Kerda Keevend, Stefanie Guimond, Judith Ng, Efe Armagan, Markus Rottmar, Inge K. Herrmann
Summary: Dental implant failure is a prevalent issue globally, with current surface modifications facing challenges in achieving sufficient integration and preventing biofilm formation. Introduction of nanostructures on the surface shows promise in improving implant-tissue contact, but existing coating processes are limited in versatility and cost. A highly modular single-step method has been developed to produce multicomponent porous bioactive nano-structured coatings on implants, with potential applications in dental implantology and beyond.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Ceramics
Hiroaki Nakade, Eita Tochigi, Bin Feng, Ryo Ishikawa, Hiromichi Ohta, Naoya Shibata, Yuichi Ikuhara
Summary: Tetragonal yttria stabilized zirconia samples with large grain size were fabricated by pulsed laser deposition and high temperature annealing. The anisotropic grain growth of tetragonal zirconia was observed, influenced by the substrate structures. The 1300 degrees C-annealed sample showed the largest grain size with homogeneous Y distributions.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Article
Thermodynamics
M. F. B. Stodt, Jan Derk Groeneveld, Lutz Maedler, Johannes Kiefer, Udo Fritsching
Summary: This study investigates the occurrence of in-flight droplet microexplosions (mu-explosions) during flame spray pyrolysis and confirms the findings through single drop experiments. It is found that there are distinct mu-explosions happening at high frequencies during the synthesis of iron oxide nanoparticles. This finding is significant for understanding the role and relevance of mu-explosions in the production and formulation of functional nanoparticles.
COMBUSTION AND FLAME
(2022)
Article
Engineering, Chemical
Jun Chen, Hao Yang, Chang-Ming Xu, Ji-Gui Cheng, Ying-Wei Lu
Summary: By using an optimized slurry with high solid content and low viscosity, zirconia microspheres with high sphericity and hardness were successfully produced through a cost-effective spray granulation method, showing potential for engineering applications.
Article
Chemistry, Physical
Ritesh Singh, Sravan Bokka, Annu Kumar Lakshya, Anirban Chowdhury
Summary: This study demonstrates the potential of CaO-doped ZrO2 nanoparticles as a dye adsorbent. Unlike previous research, this study shows that the doped-ZrO2 system alone can achieve maximum adsorption capacity for Congo red, with high surface area and rapid dye removal.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Ceramics
Xinyu Zhang, Xiaopo Cheng, Monika Jansohn, Matthias Niedermaier, Thomas Lenk, Stefan Britting, Karsten Schmidt, Richard M. Laine
Summary: Zirconia toughened aluminas (ZTAs) are important engineering ceramics with high melting points, excellent mechanical strength, and chemical stability. Through sintering flame made nanopowders, fine-grained, dense, thin ZTA films were successfully processed with optimized microstructures and sinterability under select conditions.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2021)
Article
Engineering, Chemical
Luke P. McLaughlin, Erica L. Belmont
Summary: This study examined the formation of aerosols from biomass burning emissions under laboratory pyrolysis conditions, focusing on the influence of biomass composition and dilution temperature. Results showed a significant impact of dilution temperature on particle size, number, and distribution, with the nucleation mode dominating. The summative model performed well in predicting particle number formation but highlighted uncertainty in predicting particle mass formation.
JOURNAL OF AEROSOL SCIENCE
(2021)
Article
Chemistry, Physical
Max Gaessler, Jakob Stahl, Marco Schowalter, Suman Pokhrel, Andreas Rosenauer, Lutz Maedler, Robert Guettel
Summary: This study investigates the impact of catalyst support on the dynamics of methanation and reveals that the support material plays a major role in activity, selectivity, and deactivation behavior. The adsorption of H2O strongly depends on the support material and influences the CH4 formation rate. Changes in selectivity and deactivation are observed in CO2 methanation.
Article
Engineering, Chemical
Krischan Sandmann, Manuel Falcone, Lizoel Buss, Norbert Riefler, Kiyoumars Abdoly, Hergen Oltmann, Udo Fritsching
Summary: This study presents the numerical modeling and simulation of particle dispersion during the filling process of a tubular combustion chamber. The findings reveal typical particle accumulations near the reactor wall and analyze the particle segregation and accumulation effects aside vortex structures. The measures for reducing particle segregation and inhomogeneities are discussed.
CHEMIE INGENIEUR TECHNIK
(2023)
Article
Engineering, Chemical
Stefan Christian Endres, Lutz Maedler
Summary: Accurate computation of interface curvature is crucial in simulating surface tension-dominated systems. Prior research has shown that a formulation using discrete differential geometry can find exact equilibrium solutions of surfaces, but fails to provide accurate point-wise estimates for curvatures of particle-particle capillary liquid bridges. This communication elaborates on the use of total curvatures in computing forces of parameterized models and demonstrates the infeasibility of using point-wise estimates on any asymmetric discretization.
CHEMIE INGENIEUR TECHNIK
(2023)
Article
Chemistry, Multidisciplinary
Suman Pokhrel, Jakob Stahl, Jan Derk Groeneveld, Marco Schowalter, Andreas Rosenauer, Johannes Birkenstock, Lutz Maedler
Summary: The development of a novel reactive spray technology based on the gas-phase metal oxide synthesis route opens up opportunities for producing non-oxide nanoparticles. Metal sulfides, including MnS, CoS, Cu2S, ZnS, Ag2S, In2S3, SnS, and Bi2S3, are successfully synthesized in a sulfur-rich environment. The combined approach of flame sprays and single-droplet combustion provides insights into the gas-phase formation of metal sulfides, paving the way for scalable synthesis of functional metal sulfides.
ADVANCED MATERIALS
(2023)
Article
Thermodynamics
Nithin Mohan Narayan, Saeedeh Imani Moqadam, Nils Ellendt, Udo Fritsching
Summary: This article introduces quenching as a widely applied heat treatment process for metallic materials and discusses the impact of process parameter selection on the results. It also presents a multiphase numerical modeling to analyze the cooling rate of high temperature semi-solid spheres quenched in water.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Chemistry, Physical
Tingqiang Yang, Anne Hemeryck, Suman Pokhrel, Wen Chen, Lutz Maedler, Udo Weimar, Nicolae Barsan
Summary: The combination of operando DRIFTS measurement and DFT calculation reveals the counterintuitive HCHO sensing mechanism of In4Sn3O12. At the optimum temperature of 200 degrees C, HCHO undergoes partial oxidation to formate (or HCOOH) with medium activation energy (0.43-0.68 eV) and sufficient electron donation effect, resulting in the generation of sensor signal. The Sn(3a)-connected O acts as the active site, playing crucial roles in both HCHO adsorption and partial oxidation.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Beeke Gerken, Christoph Mahr, Jakob Stahl, Tim Grieb, Marco Schowalter, Florian F. Krause, Thorsten Mehrtens, Lutz Maedler, Andreas Rosenauer
Summary: Hetero-contacts are interfaces between different materials at the nanoscale leading to novel functional properties. In hetero-aggregates, primary particles of at least two different materials are mixed at primary particle or cluster level. Double flame spray pyrolysis (DFSP) is a versatile technique for the controlled synthesis of such materials. Characterization of hetero-aggregates by scanning transmission electron microscopy (STEM) requires acquisition and evaluation of many aggregate images in order to derive statistically significant results. Usually, STEM energy dispersive X-ray spectroscopy (EDXS) is used to acquire elemental maps providing the material distribution of the primary particles within hetero-aggregates. However, the acquisition of a single EDXS map takes up to several minutes. For this reason, determination of material types of primary particles from the intensity in high-angle annular dark field STEM images alone is desirable. These images can be acquired within a couple of seconds. In the present work, a method is suggested which allows for achieving this objective. It can be applied to distinguish materials with a significant difference in their atomic number and hence sufficient material contrast in the STEM images.
PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION
(2023)
Article
Thermodynamics
Shahram Mohammadi, Jalal Poostforooshan, Malte F. B. Stodt, Vinzent Olszok, Johannes Kiefer, Udo Fritsching, Alfred P. Weber
Summary: In this work, MnOx nanoparticles were synthesized by a continuous electrospray-assisted flame spray pyrolysis (EAFSP) method. The precursor solutions containing MnN dissolved in 1-propanol were atomized into charged droplets by electrospray and then enter the flame without dispersion gas. The high-temperature residence times of the droplets were controlled by varying the horizontal injection locations, resulting in MnOx nanoparticles with tunable properties. Various diagnostics were used to analyze the formation and crystal phases of the MnOx nanoparticles, and phase-Doppler anemometry experiments were conducted to study the combustion behavior of electrosprayed MnN droplets.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Article
Thermodynamics
Arne Witte, Lutz Maedler
Summary: Flame spray pyrolysis (FSP) is a powerful and versatile technique for synthesizing functional nanoparticles. The study of isolated burning FSP droplets is crucial for understanding and improving this technique. In this study, the burning process of single droplets with different sizes and the effect of solvent composition were investigated. The results provide insights into droplet combustion and the use of low-cost precursor-solvent systems in FSP.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Article
Optics
Alessia Di Vito, Peyman Amiri, Steffen Bornemann, Georg Schottler, Maximilian Vergin, Florian Meierhofer, Jan Guelink, Andreas Waag, Joan Canals, Angel Dieguez, J. Daniel Prades, Matthias Auf Der Maur
Summary: The design study presents a micro illumination tool based on GaN microLED arrays. By optimizing the structural parameters, the extraction efficiency and spatial resolution of the resulting light patterns are improved. Adding an In-GaN micro-lens array achieves the best performance.
Article
Biochemistry & Molecular Biology
Anja Heyse, Miriam M. Gossmann, Patrick Giefer, Patrizia Gaebel, Udo Fritsching, Anja M. Wagemans, Stephan Drusch
Summary: Fouling due to biomolecule adsorption remains a drawback for membrane emulsification. This study investigated the fouling effect on the membrane and the modified enzyme. Through experiments and simulations, it was found that increasing lipase concentration led to higher fouling and decreased wetting of the membrane. The pH of the lipase solution also affected the microstructure of the foulant layer. Despite enzyme mass loss, the structural and functional characteristics of lipase were not significantly affected.
PROCESS BIOCHEMISTRY
(2023)
Article
Engineering, Chemical
Udo Fritsching, Lizoel Buss, Teresa Tonn, Lukas Schumski, Jurgen Gakovi, Johnson David Hatscher, Jens Soelter, Kerstin Avila, Bernhard Karpuschewski, Julian Frederic Gerken, Tobias Wolf, Dirk Biermann, Christian Menze, Hans-Christian Moehring, Elio Tchoupe, Lukas Heidemanns, Tim Herrig, Andreas Klink, Kaissar Nabbout, Martin Sommerfeld, Fabian Luther, Ingo Schaarschmidt, Andreas Schubert, Markus Richter
Summary: Metalworking operations rely on the successful application of metalworking fluids (MWFs) for effective and efficient operation. This paper discusses promising flow visualization techniques applied to different machining processes, which can help determine efficient machining parameters and MWF applications.
Article
Thermodynamics
M. F. B. Stodt, J. Kiefer, U. Fritsching
Summary: Flame spray pyrolysis (FSP) is a technique for the synthesis of metal oxide nanoparticles by combusting precursor solutions in a spray flame. In this study, the influence of jet Reynolds number and turbulence on droplet dynamics and the synthesis of iron oxide nanoparticles by FSP is investigated. It is found that the presence of μ-explosions in the spray flame leads to the conversion of droplet sizes from unimodal to bimodal droplet size distribution (DSD). The results show that higher jet Reynolds numbers result in narrower DSD and sharper separation of DSD probability peaks.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Article
Thermodynamics
Pedro Bianchi Neto, Lizoel Buss, Malte F. B. Stodt, Udo Fritsching, Dirceu Noriler
Summary: In order to accurately model and simulate the flame spray pyrolysis process, all relevant phenomena must be considered. A combination of computational fluid dynamics (CFD) and a population balance model (PBM) is used to investigate the impact of thermophoresis and other parameters on particle size. The flame spray process is simulated using CFD and a monodisperse solver for a bivariate PBM is implemented to simulate nanoparticle formation and evolution. The model is validated using experimental data and shows accurate results for some cases.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Article
Physics, Fluids & Plasmas
Manuel Falcone, Lizoel Buss, Udo Fritsching
Summary: This article analyzes a new vibration-assisted drilling process for the manufacturing of extremely hard materials. It applies multiphase computational fluid dynamics to study the MQL gas/liquid transport in the presence of a vibrating and rotating twist drill bit. The article utilizes an open-source Smoothed Particle Hydrodynamics (SPH) meshless method to overcome the limitations of conventional mesh-based methods in analyzing lubrication media flow. However, the study finds that the SPH method does not provide satisfactory results in terms of solution plausibility and computational cost.
