Effect of Sample Preparation on SEM Imaging of Er³⁺,Yb³⁺-Doped SrLaAlO₄ Luminescent Ceramics
Chávez Campos, David Alejandro; Aguilar González, Miguel Ángel; Rodríguez García, Carlos Eduardo; Castelán, Mario
David Chávez¹˒², Miguel Ángel Aguilar-González³, Carlos Eduardo Rodríguez-García⁵, Mario Castelán¹* ¹ Robotics and Advanced Manufacturing, Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV), Industria Metalúrgica, Ramos Arizpe, 25900, Coahuila, México. ² Secretaría de Ciencia, Humanidades, Tecnología e Innovación (SECIHTI), Mexico City, México. ³ Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV), Industria Metalúrgica, Ramos Arizpe, 25900, Coahuila, México. ⁴ Centro de Física Aplicada y Tecnología Avanzada (CFATA), Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Querétaro, 76230, Querétaro, México. ⁵ Faculty of Physical and Mathematical Sciences, Autonomous University of Coahuila (UAdeC), Prol. David Berlanga, Saltillo, 25280, Coahuila, México.
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Abstract
Rare-earth-doped upconversion materials exhibit optical and structural properties that are strongly influenced by particle morphology, agglomeration, and porosity. In this work, the influence of sample preparation on the scanning electron microscopy (SEM) characterization of Er³⁺,Yb³⁺-doped SrLaAlO₄ phosphors synthesized by solution combustion was investigated. Three compositions with controlled variations in nitrate and urea contents were prepared and subsequently annealed at 1000 °C for 6 h. A sequential SEM preparation methodology was evaluated by comparing untreated powders (P1), graphite-coated powders (P2), and powders subjected to ultrasonic dispersion prior to graphite coating (P3). Structural characterization confirmed the formation of tetragonal SrLaAlO₄, while SEM observations revealed significant differences in morphological readability depending on sample preparation. Graphite coating reduced charging-related artifacts and improved image stability, whereas ultrasonic dispersion promoted the disruption of weak secondary agglomerates and enhanced the visualization of particle boundaries and porous features. Differences in aggregation and morphology were also observed among the synthesized compositions, indicating an influence of precursor-to-fuel variations on the resulting microstructure. These results demonstrate that appropriate sample preparation is essential for reliable SEM interpretation of combustion-synthesized luminescent ceramic powders and provides a reproducible basis for subsequent quantitative image analysis and microstructural characterization.
Keywords: Computer Vision; SrLaAlO4; SEM