Fig. 1. Annealing process curve of MgAl₂O₄ transparent ceramic sample

Fig. 2. Optical transmittance curve of annealed MgAl₂O₄ transparent ceramic sample

Fig. 3. Cross-sectional morphology of MgAl₂O₄ transparent ceramic samples before and after annealing. (a) Unannealed; (b) Annealed at 1 300 ℃; (c) Annealed at 1 400 ℃; (d) Annealed at 1 500 ℃

Fig. 4. Influence curve of porosity on material transmittance

Fig. 5. Influence curve of pore size on the optical transmittance of the material

Fig. 6. Stress result of the annealed MgAl₂O₄ transparent ceramic samples

Fig. 7. Raman spectra of MgAl₂O₄ powder and annealed transparent ceramic samples (excited by 785 nm laser)

Fig. 8. E_g mode Raman peaks and their fitting curves of MgAl₂O₄ powder and annealed transparent ceramic samples

Fig. 9. Effect of annealing temperature on the drift of E_g mode Raman peak of magnesium-aluminum spinel

Fig. 10. X-ray diffraction spectra of MgAl₂O₄ powder and annealed transparent ceramic samples