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Sellschopp K, Vonbun-Feldbauer GB. Mechanical properties of TiO 2/carboxylic-acid interfaces from first-principles calculations. NANOSCALE 2023; 15:16967-16975. [PMID: 37823858 DOI: 10.1039/d3nr01045g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Nature forms structurally complex materials with a large variation of mechanical and physical properties from only very few organic compounds and minerals. Nanocomposites made from TiO2 and carboxylic-acids, two substances that are available to nature as well as materials engineers, can be seen as representative of a huge class of natural and bio-inspired materials. The hybrid interfaces between the two components are thought to determine the overall properties of the composite. Yet, little is known about the atomistic processes at those interfaces under load and their failure mechanisms. The present work models the stress-strain curves of TiO2/carboxylic-acid interfaces in the slow deformation limit for different facets and binding modes, employing density functional theory calculations. Contrary to former hypotheses, the interface rarely fails through a de-bonding of the molecule, but rather through a surface failure mechanism. Furthermore, a stress-release mechanism is discovered for the bi-dentate binding mode on the {101} facet. Deriving mechanical properties, such as the interface strength, strain at interface failure, and the elastic modulus, allows a comparison with experimental results. The calculated strengths and elastic moduli already agree qualitatively with properties of nanocomposites, despite the simplifications in the model consisting of periodic sandwich structures. The results presented here will help to improve these materials and can be directly integrated in multi-scale simulations, in order to reach a more accurate quantitative description.
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Affiliation(s)
- Kai Sellschopp
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Hamburg, Germany.
| | - Gregor B Vonbun-Feldbauer
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Hamburg, Germany.
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Velosa-Moncada LA, Raskin JP, Aguilera-Cortés LA, López-Huerta F, Herrera-May AL. Estimation of the Young's Modulus of Nanometer-Thick Films Using Residual Stress-Driven Bilayer Cantilevers. NANOMATERIALS 2022; 12:nano12020265. [PMID: 35055286 PMCID: PMC8778095 DOI: 10.3390/nano12020265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/08/2022] [Accepted: 01/11/2022] [Indexed: 02/05/2023]
Abstract
Precise prediction of mechanical behavior of thin films at the nanoscale requires techniques that consider size effects and fabrication-related issues. Here, we propose a test methodology to estimate the Young’s modulus of nanometer-thick films using micromachined bilayer cantilevers. The bilayer cantilevers which comprise a well-known reference layer and a tested film deflect due to the relief of the residual stresses generated during the fabrication process. The mechanical relationship between the measured residual stresses and the corresponding deflections was used to characterize the tested film. Residual stresses and deflections were related using analytical and finite element models that consider intrinsic stress gradients and the use of adherence layers. The proposed methodology was applied to low pressure chemical vapor deposited silicon nitride tested films with thicknesses ranging from 46 nm to 288 nm. The estimated Young’s modulus values varying between 213.9 GPa and 288.3 GPa were consistent with nanoindentation and alternative residual stress-driven techniques. In addition, the dependence of the results on the thickness and the intrinsic stress gradient of the materials was confirmed. The proposed methodology is simple and can be used to characterize diverse materials deposited under different fabrication conditions.
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Affiliation(s)
- Luis A. Velosa-Moncada
- Micro and Nanotechnology Research Center, Universidad Veracruzana, Boca del Rio 94294, Mexico;
| | - Jean-Pierre Raskin
- Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Université Catholique de Louvain (UCL), 1348 Louvain-la-Neuve, Belgium;
| | | | - Francisco López-Huerta
- Facultad de Ingeniería Eléctrica y Electrónica, Universidad Veracruzana, Boca del Rio 94294, Mexico;
| | - Agustín L. Herrera-May
- Micro and Nanotechnology Research Center, Universidad Veracruzana, Boca del Rio 94294, Mexico;
- Maestría en Ingeniería Aplicada, Facultad de Ingeniería de la Construcción y el Hábitat, Universidad Veracruzana, Boca del Rio 94294, Mexico
- Correspondence:
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Hartmann H, Beyer JN, Hansen J, Bittinger SC, Yesilmen M, Schlicke H, Vossmeyer T. Transfer Printing of Freestanding Nanoassemblies: A Route to Membrane Resonators with Adjustable Prestress. ACS APPLIED MATERIALS & INTERFACES 2021; 13:40932-40941. [PMID: 34415725 DOI: 10.1021/acsami.1c11431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Freestanding nanoassemblies represent a new class of functional materials with highly responsive optical, electrical, and mechanical properties. Hence, they are well-suited for applications in advanced sensor devices. Here, it is shown that transfer printing enables the well-controlled fabrication of freestanding membranes from layered nanoassemblies: Using a polydimethylsiloxane (PDMS) stamp, thin films (thickness: ∼45 to ∼51 nm) of 1,6-hexanedithiol cross-linked gold nanoparticles (diameter: ∼3.9 ± 0.8 nm) were transferred onto surface-oxidized silicon substrates featuring square microcavities with edge lengths of ∼78 μm. After adjusting the contact pressure to 1.8 bar, intact membranes were printed in yields of ∼70%. The prestress of printed membranes was determined by measuring their resonance frequencies under electrostatic actuation. In general, the prestress values were in the ∼10 MPa range with standard deviations below 10% for parallel printed resonators. The deviations in average prestress between resonators printed onto different substrates were 21% or less. By increasing the temperature during the final transfer step from 5 to 48 °C, it was possible to tune the average prestress from ∼14 to ∼28 MPa. This effect was attributed to the pronounced thermal expansion of the PDMS stamp. Finally, by transfer printing layered films of graphene oxide/silk fibroin (GO/SF), it is shown that the approach can be adapted for the fabrication of freestanding membranes from very different nanomaterials.
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Affiliation(s)
- Hauke Hartmann
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Jan-Niklas Beyer
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Jan Hansen
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Sophia C Bittinger
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Mazlum Yesilmen
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Hendrik Schlicke
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
- Fraunhofer Center for Applied Nanotechnology, Grindelallee 117, 20146 Hamburg, Germany
| | - Tobias Vossmeyer
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
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Sellschopp K, Heckel W, Gäding J, Schröter CJ, Hensel A, Vossmeyer T, Weller H, Müller S, Vonbun-Feldbauer GB. Shape-controlling effects of hydrohalic and carboxylic acids in TiO 2 nanoparticle synthesis. J Chem Phys 2020; 152:064702. [PMID: 32061241 DOI: 10.1063/1.5138717] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The ability to synthesize nanoparticles (NPs), here TiO2, of different shapes in a controlled and reproducible way is of high significance for a wide range of fields including catalysis and materials design. Different NP shapes exhibit variations of emerging facets, and processes such as adsorption, diffusion, and catalytic activity are, in general, facet sensitive. Therefore, NP properties, e.g., the reactivity of NPs or the stability of assembled NPs, depend on their shape. We combine computational modeling based on density functional theory with experimental techniques such as transmission electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray powder diffraction to investigate the ability of various adsorbates, including hydrohalic and carboxylic acids, to influence NP shape. This approach allows us to identify mechanisms stabilizing specific surface facets and thus to predict NP shapes using computational model systems and to experimentally characterize the synthesized NPs in detail. Shape-controlled anatase TiO2 NPs are synthesized here in agreement with the calculations in platelet and bi-pyramidal shapes by employing different precursors. The importance of the physical conditions and chemical environment during synthesis, e.g., via competitive adsorption or changes in the chemical potentials, is studied via ab initio thermodynamics, which allows us to set previous and new results in a broader context and to highlight potentials for additional synthesis routes and NP shapes.
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Affiliation(s)
- K Sellschopp
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany
| | - W Heckel
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany
| | - J Gäding
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany
| | - C J Schröter
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - A Hensel
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - T Vossmeyer
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - H Weller
- Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - S Müller
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany
| | - G B Vonbun-Feldbauer
- Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany
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