A Thermodynamic‐Guided Spark Plasma Sintering Approach for the Fabrication of High‐Performance Fluorophosphate Glasses

Fluorophosphate (FP) glasses are promising materials for advanced photonic applications, yet their performance is often compromised by challenges in conventional high‐temperature melting (HTM) synthesis, such as fluoride volatilization and hydroxyl contamination. This study introduces a comprehensive strategy to overcome these limitations by integrating thermodynamic prediction with an advanced fabrication technique. First, a thermodynamic method was employed to successfully predict the glass‐forming region (GFR) of the RF n –AlF 3 –Sr(PO 3 ) 2 system, enabling the rational design of FP compositions with excellent anti‐crystallization stability (Δ T > 100°C), a high elastic modulus (up to 123.2 GPa), and a low nonlinear refractive index (1.06–1.17 × 10 −13 esu). Subsequently, a comparative investigation was conducted on Nd 3+ ‐doped MgF 2 –AlF 3 –Sr(PO 3 ) 2 –Ba(PO 3 ) 2 glasses prepared by conventional HTM and spark plasma sintering (SPS). The results demonstrate that the rapid, low‐temperature, vacuum‑assisted SPS process significantly enhances fluorine retention by up to 76% and drastically reduces the hydroxyl absorption coefficient from over 10 to 0.09 cm −1 , which induce structural modifications and favorably alters the physical and 4 F 3/2 → 4 I 9/2 transition properties of Nd 3+ ‐doped FP glasses. Specifically, glasses fabricated via SPS exhibit higher hardness, reduced nonlinear effects, enhanced emission intensity, a more symmetric local ligand field, and an increase in fluorescence lifetime by up to 38%. This work establishes an efficient paradigm for developing high‐performance FP glasses and provides fundamental insights into their composition–processing–structure–property relationship, paving the way for next‐generation optical materials and devices.