Abstract
Nanoparticle properties are correlated to their size, size distribution, and shape; it is essential to accurately measure these features in the field of nanoscience. In this study, silver nanoparticles (AgNPs) were synthesized with the ultrasonic-spray-pyrolysis (USP) method from a water solution of silver nitrate. The synthesized AgNPs were characterized by Dynamic Light Scattering (DLS) analysis and Scanning Electron Microscopy (SEM) to reveal their size and size distribution. A search algorithm based on an image-processing technique to obtain particle size and particle-size distribution from SEM micrographs is proposed. In order to obtain more quantitative information and data with respect to the morphology of particles synthesized under different process parameters, SEM micrographs with a nonhomogeneous background contrast were examined via image-processing techniques in MATLAB. Due to the inhomogeneous contrast of SEM micrographs, defining an overall threshold value was insufficient in the detection of whole nanoparticles. Thus, subimages were directly created according to the maximum and minimum particle size specified by the user to determine local threshold values. The obtained results were automatically combined to represent both particle dimension and location in the SEM micrographs. We confirmed that the results of our DLS analysis, theoretical calculation, and image-processing technique were correlated with our expected results.
Highlights
Materials 2020, 13, 38 the synthesis of pure, spherical, and fine nanoparticles as part of a one-step process. This technique is capable of synthesizing metal/metal oxides with precisely controllable chemical composition, and particle size and morphology by manipulating process parameters such as solution concentration, temperature, gas-flow rate, and ultrasound frequency [15,16,17,18,19,20,21,22]
Particle size and size distribution can be defined by Dynamic Light Scattering (DLS) analysis, but this requires extra analysis costs, and it remains difficult to accurately evaluate particle size and particle-size distribution due to the adhesion of nanoparticles
A search algorithm based on the image-processing technique to analyze particle size and size distribution was proposed
Summary
The unique chemical and physical properties of nanoparticles (NP) have led to their extensive use in various applications, including in the optical, electronic, magnetic, biomedical, and catalysis fields [1,2,3,4,5].Silver NPs (AgNPs) have especially attracted considerable attention in diverse applications due to their superior properties, such as antimicrobial activity, and electrical and thermal conductivity [6,7,8,9].Many methods have been employed for the synthesis of AgNPs: laser ablation, chemical reduction, solution combustion, and electrochemical and spray pyrolysis [10,11,12,13,14]. Materials 2020, 13, 38 the synthesis of pure, spherical, and fine nanoparticles as part of a one-step process This technique is capable of synthesizing metal/metal oxides with precisely controllable chemical composition, and particle size and morphology by manipulating process parameters such as solution concentration, temperature, gas-flow rate, and ultrasound frequency [15,16,17,18,19,20,21,22]. To obtain AgNPs with these desired properties, controlling and determining the size, size distribution, morphology, and composition of nanoparticles plays a critical role For this purpose, analysis methods can be used for the detection of the properties of NPs. The mean diameter of NPs with a spherical shape synthesized by the USP technique can be theoretically calculated; particle-size distribution cannot be obtained by this calculation [21,22]. The measurement of particle size can be accomplished from Scanning
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