Study of the influence of three different complexing agent on the sol-gel fabrication and optical properties of Ce ion doped strontium aluminate

Inorganic luminescent materials in most cases consist of rare-earth ion embedded in the crystalline matrix. One of the widely studied matrices is the group of strontium aluminates. In SrO–Al2O3 system, there are many possible phases, namely Sr3Al2O6, SrAl2O4, SrAl4O7, SrAl12O19, Sr4Al2O7, Sr4Al14O25, Sr12Al14O33 and Sr10Al6O19, as described in the literature. A lot of attention has been concentrated on Sr4Al14O25 phase. In this study, Sr₄Al₁₄O₂₅ was synthesized via the sol-gel method using boric acid (H₃BO₃) as an auxiliary agent at different temperatures. Boric acid was found to lower the synthesis temperature, shorten calcination time, aid crystallization, and stabilize phases. Cerium (Ce), a rare earth metal, was then doped into the structure at varying concentrations and holding times. Three complexing agents—ethylene glycol (EG), ethylenediaminetetraacetic acid (EDTA), and citric acid (CA)—were used separately to evaluate their effects on the synthesis process. Structural analysis using XRD data showed that none of the agents altered the base structure of strontium aluminate. However, optical properties varied: citric acid resulted in the highest absorbance, while ethylene glycol led to the highest reflectance. These findings contribute to understanding the role of complexing agents in tuning optical behavior in Ce-doped strontium aluminates.