Shedding Electrons on Cenospheres: Advancing Characterization Through X‐ray Micro‐Analysis

Abstract

Cenospheres are hollow spherical structures derived from coal fly ash waste. They exhibit unique properties such as thermal stability, lightweight composition, inertness, and energy attenuation, which make them ideal for advanced material applications. Due to their cost‐effectiveness and wide availability, they are viable alternatives to specialized micro‐ and nanospheres synthesis. However, the limited understanding of cenospheres and the complexities involved with characterization techniques hinder the utilization of their valuable attributes effectively. Our study introduces a novel methodology for classifying and characterizing cenospheres using X‐ray microanalysis coupled with energy‐dispersive X‐ray spectroscopy (EDS). Herein, we identify inherent X‐ray emission profiles for the cenospheres and solid spheres (which look similar to the untrained eye), enabling rapid classification through EDS line scans. Further, we establish a characterization threshold for the line scans, that is, half the penetration depth at 99% X‐ray intensity for specific accelerating voltages. We propose a non‐destructive technique for measuring the cell wall thickness and introduce error corrections for measurements at lower accelerating voltages. When using higher voltages, the measurement of cell wall thickness yields RMSE values of 0.41 for entering cell walls and 0.21 for exiting cell walls. These values provide specific measurements for the thickness of individual cell walls quantitatively rather than relying on more generalized theoretical relationships.