研究目的
Investigating the kinetics of Cr3+ to Cr4+ ionic transformation and Cr4+ migration between the “A” and “D” coordinated positions in Cr,Ca:YAG laser ceramics under oxidation annealing conditions.
研究成果
The oxidation process of Cr3+ in Cr,Ca:YAG ceramics is limited by the diffusion of oxygen, with an activation energy of 2.7 ± 0.2 eV. The intralattice cation exchange of Cr4+ between “A” and “D” sites is faster than Cr3+ to Cr4+ oxidation and is thermodynamically driven by entropy in the temperature range of 900–1300 ○C.
研究不足
The study is limited to Cr,Ca:YAG ceramics prepared by solid-state reaction sintering. The activation energy for Cr4+ exchange between “A” and “D” sites was not determined due to the short saturation time.
1：Experimental Design and Method Selection:
The kinetics of Cr4+ formation was studied by annealing Cr,Ca:YAG ceramics in ambient air at different temperatures and times. The Jander model was used to analyze the oxidation kinetics.
2：Sample Selection and Data Sources:
High purity Al2O3, Y2O3, Cr2O3, and CaO were used as starting materials. The samples were prepared by solid-state reaction sintering.
3：List of Experimental Equipment and Materials:
SEM (JEOL JSM-6390LV), UV/Vis spectrophotometer (Perkin Elmer 35), HRTEM, XRD analysis (DRON-3 diffractometer).
4：Experimental Procedures and Operational Workflow:
The samples were annealed in air at different temperatures, and the optical absorption spectra were collected to monitor Cr4+ formation.
5：Data Analysis Methods:
The Smakula-Dexter formula was used to estimate the concentration of Cr4+ ions. The Jander model was applied to determine the kinetics of Cr3+ oxidation.
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