Quantification of Size Distribution and Crystallinity in Functional Nanoparticle Systems

• Grant number: 25/01013-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: February 28, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Sérgio Luiz Morelhão
• Grantee: Valeria Karuna Camargo Molina
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Controlling the shape and size dispersivity, as well as the crystallinity of nanoparticles (NPs), is a challenge that impacts the understanding of the role of these parameters in the physical and chemical properties of NP samples. Reliable quantitative tools to analyze NP dispersivity and crystallinity are essential for optimizing scalable synthesis routes and controlling NP properties, such as catalytic performance and nonlinear optical response. The most common tools to analyze NP dispersivity and crystallinity are electron microscopy (EM) and X-ray scattering techniques, such as wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS). However, each technique has specific limitations and susceptibilities to different parameters. WAXS, for example, is essential to obtain information on the crystallinity of NPs, while EM and SAXS are necessary to analyze the particle size distribution. EM provides average values over small NP ensembles, whereas X-ray techniques access bulk values. SAXS is influenced by NP-NP interaction distances, and SAXS and WAXS weight the size distribution with different weights, adding another layer of complexity to the analysis. Due to the variables and limitations of each individual technique, reliable characterization of NPs requires the combination of different methods. Recent advances in theoretical and experimental concepts allow combining SAXS and WAXS results. In this work, aiming to consolidate the applicability of these concepts, they will be applied to large catalytic NPs (~100 nm) and small ferromagnetic NPs (~10 nm).