Comment caractériser la structure des nanomatériaux dans le développement des matériaux ?

Nano material's structure determines the various properties and the capabilities of the material. Some of them include shape, size, bonding with other materials, and stability. All these factors causes the difference in physicochemical and electromechanical properties. A common example would be Carbon, which can be either Graphene, CNTs, Fullerenes and Diamond depending on the structure. Due to their different properties, each of them excel in variety of applications.

Methods used to characterize nanomaterials Microscopy techniques X-ray techniques X-ray diffraction (XRD) Spectroscopic analysis methods Ultraviolet and visible spectroscopy Raman spectroscopy Nuclear magnetic resonance (NMR) Solid state NMR Thermal analysis Differential scanning calorimetry (DSC) Thermogravimetric Analysis (TGA) Particle size and surface area analysis Dynamic Light Scattering (DLS) BET surface area analysis (Brunauer-Emmett-Teller): Electron spectroscopy X-ray photoelectron spectroscopy (XPS) Analysis Electron Spectroscopy (AES) Magnetic characterization Superconducting quantum interference device (SQUID) Zeta potential measurement On-site technologies In situ X-ray absorption spectroscopy (XAS)

Common techniques Used- HRTEM - Offers high-resolution imaging and provides details about particle morphology size and crystallinity. FESEM - surface images gives information about the structure of nano materials. AFM - It scan, surface topography at the atomic or nanoscale , created 3D information. XRD - Determines the crystal structure of materials by analyzing the diffraction patterns. Give Phase information. PSA -DLS- Measures particle size distribution in a liquid medium by scattered of light. FTIR - It identifies functional groups information XPS- gives elemental composition and chemical state of materials by measuring the binding energies of electrons very close to top surface

Transmission Electron Microscope is the most definitive way. It depends on the type of structure you are looking for, your budget, and your skill level.

Various techniques are employed to characterize the structural properties of nanomaterials: 1-Size: TEM SEM Atomic Force Microscopy (AFM) Dynamic Light Scattering (DLS) 2-Shape: TEM SEM AFM X-ray Diffraction (XRD) 3-Surface Area: BET analysis Gas adsorption techniques (e.g., nitrogen adsorption) 4-Crystallinity: XRD Selected Area Electron Diffraction (SAED) in TEM Raman Spectroscopy FTIR 5-Defects and Interfaces: TEM Electron Energy Loss Spectroscopy (EELS) XPS

The characterization of nanomaterials presents unique challenges, primarily due to their small size, which often results in weaker signals during analysis. This necessitates the use of combined characterization techniques for a more accurate and reliable understanding. Techniques such as XRD, TG-DSC for thermal properties, SEM/TEM for structural details, and EDS or X-ray scattering for elemental analysis are essential. The choice of technique combination depends on the application to ensure the relevance and depth of the analysis. Such an approach is crucial for a comprehensive characterization, highlighting the importance of a multifaceted strategy in nanomaterials research.

Characterizing nanomaterial structures is complex, requiring precise techniques to reveal subtle features beyond human perception. Sample variability necessitates careful selection of instruments for accurate insights. Diverse attributes like size, shape, and composition add complexity, demanding meticulous navigation. Integrating data from various techniques requires sophisticated analysis, highlighting the intricacies of unraveling nanomaterial structures.

There are many different ways to characterize nanomaterials. Whether that’s their chemical, structural of physical properties each characterisation provides its own unique challenges. For example, a sample can be characterised using transmission electron microscopy (TEM), UV Visible (UV-VIS) and perhaps X-Ray Diffraction (XRD). These challenges will presented itself in a form of data analysis, characterisation availability and some of the common problems I have to face is to look for databases to match your dataset.

Nanomaterials are challenging to characterize because of their small size, intricate forms, and varied compositions, which renders conventional methods ineffective. Contaminants and variations in synthesis techniques might muddle results. Analysis is made more difficult by surface changes and aggregation of nanoparticles. Furthermore, logistical and financial difficulties might arise since specialist knowledge and equipment are frequently needed. There are extra hurdles in ensuring measurement accuracy, repeatability, and reliability when considering environmental interactions and sample variability. In nanomaterial research, accurate and trustworthy characterization is still a significant challenge.

During my PhD Tenure, I have found SEM and TEM as best tools for characterization of NPs. However, these techniques are only for physical , morphological and upto certain extent for stoichiometric description, more important characterization is on application of NPs. One may use photo luminescence technique too for getting more details on functionality of particles. I had used I-V characterizations at different bias conditions to see the effect of size of NPs on their switching capabilities, both light/dark J-V characterizations for their potential use as photoelectric devices, impedance spectroscopy to understand the interfaces & trap assisted conduction. Its a vast field, depends on type of material and application you are working on!

In my experience, various characterization techniques and tools are required to get an accurate result. Start with HR-SEM to have an overview of the nanoparticle's shape and estimated size and aggregation. Then, use HR-TEM to get the exact nanoparticle size! You can then use the DLS to measure zeta potential, average diameter, and polydispersity! Combining those 3 is the easiest and best approach. You should definitely use X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy or infrared spectroscopy for chemical structure. More advanced is X-ray Absorption Near Edge Structure (XANES)

1. Transmission Electron Microscopy (TEM): Offers detailed information on NPs size, shape, and structure. 2. Scanning Electron Microscopy (SEM): Provides high-resolution images of surface morphology. 3. Dynamic Light Scattering (DLS): Measures particle size distribution in solution. 4. X-ray Diffraction (XRD): Identifies crystal structure and composition. 5. Fourier Transform Infrared Spectroscopy (FTIR): Analyzes chemical composition and functional groups. 6. Atomic Force Microscopy (AFM): Maps surface topography and measures forces at the nanoscale. 7. UV-Visible Spectroscopy: Determines optical properties - absorption and bandgap 8. Brunauer, Emmett and Teller (BET): Surface area analysis 9. Fluorescence (PL) Spectroscopy: PL measurement

It mainly depends on the result outcome needed in the particular research. For surface morphology Scanning electron microscopy (SEM) is used, for internal structures and in-situ morphology Transmission electron microscopy (TEM) is used. For the dimension of nano materials such that thickness of layer and width atomic force microscopy (AFM) is used. There are plenty other techniques for particle size, chemical bonds/ groups and structures as well.

One thing I have found helpful while characterizing the materials is the use of electron microscopy. They are the most commonly used techniques for the characterization of nanoparticles.

The main factors to consider for the Nanomaterials characterization are: Size of the material Phase of the material Physical properties Cost effectiveness

Selecting the optimal technique for characterizing nanomaterials involves considering factors like material type and size, intended property or function, and instrument availability and cost. For instance, TEM offers high-resolution imaging but requires thin samples, while XRD reveals crystal structure and phase. SEM and TEM are complex and costly, needing vacuum and skilled operators, whereas XPS and infrared spectroscopy are simpler and cheaper, operating in ambient conditions. Evaluating these factors is crucial for choosing the most suitable technique.

Determine the exact properties of interest, such as size, shape, composition, and surface characteristics, before applying the appropriate methods for nanomaterial characterization. Based on these characteristics, choose the correct techniques, such as spectroscopy for chemical composition, XRD for crystalline structure, and electron microscopy for morphology. For reliable findings, ensure sample preparation and equipment calibration follow established procedures. Lastly, the data must be thoroughly analyzed to learn more about the characteristics and behavior of nanomaterials.

I think that the best characterization techniques for your materials depend on the material type, size and shape. Personally, to determine that my exfoliated graphene material is a monolayer graphene, I use Raman Spectroscopy. Also, to determine the different thicknesses of my hBN, I use atomic force microscopy to determine them. Hence, it depends on the type of material in question.

Combination of two or more techniques can give definitive information about the nano material. In addition to this, correlative techniques can be used, typical example is SEM-EDS, while SEM can give you the morphology, EDS gives elemental information and this both exists in the same instrument. Similar to this, in Correlative EDS-Raman, Raman gives info about chemical bonds and structure of the sample. Herein the limitations of one technique can be covered by the other.

Integrating several methods for characterizing nanomaterials improves the accuracy and comprehensiveness of the findings. For example, information on morphology and chemical composition can be obtained by combining electron microscopy with spectroscopic techniques. Similarly, an understanding of crystalline structure and thermal stability may be gained by combining X-ray diffraction with thermal analysis methods. In addition, surface charge and particle size distribution may be obtained by coupling zeta potential measurements with dynamic light scattering. This approach will help researcher make better-informed decisions and inferences in various applications of nanomaterials.

From my experience, there is a logical approach to follow in nanoparticle characterization. Start with HR-SEM to get an overview of the particle's size, aggregation, morphology, and shape. Then, move to Raman, FTIR, or more advanced XPS for chemical structure. X-ray absorption near edge structure (XANES) is an incredible technique, too, if you can access it. Then, you can use Dynamic light scattering for the average particle's diameter, zeta potential, and polydispersity. Finally, you should use TEM to measure the particle size accurately!

A major challenge for nano materials would be 'Reproducibility' of characterization results as even the slightest deviation could affect. Standardization of analysis method with the consideration of materials stability would be one of the ways to overcome this during characterization.

Let me summarize the answer here , characterizing nanomaterials is essential for understanding their properties and ensuring their suitability for specific applications. Here are some techniques we commonly use in material development: 1.Scanning Electron Microscopy (SEM) 2. Transmission Electron Microscopy (TEM) 3. X-ray Diffraction (XRD) 4. Dynamic Light Scattering (DLS) 5.Atomic Force Microscopy (AFM) 6.Thermogravimetric Analysis (TGA) 7. Spectroscopic Techniques (UV-Vis, FTIR, Raman) 8. Surface Area Measurement (BED) for surface area and porosity of nanomaterials. 9. Zeta Potential Measurement 10.Electron Energy Loss Spectroscopy (EELS)