1. XRD patterns of the raw and heat-treated (at 1400 ℃ for 5 h) nano-γ-Al₂O₃ (the standard patterns for γ-Al₂O₃ and α-Al₂O₃ are also given) (a), XRD patterns of MgAl₂O₄:Mn phosphors synthesized using alumina sources with different α/(α+γ) ratios (b), and photoluminescence emission spectra of the MgAl₂O₄:Mn synthesized using alumina sources with different α/(α+γ) ratios (λ_ex=365 nm) and the excitation spectra monitored for 520 and 651 nm emission of MgAl₂O₄:Mn with α/(α+γ)=50% (c)

2. Digital images (λ_ex=365 nm) of the MgAl₂O₄:Mn phosphors synthesized using the alumina sources with different α/(α+γ) ratios

3. UV-Vis-NIR diffuse reflectance spectra of the MgAl₂O₄:Mn synthesized using alumina sources with different α/(α+γ) ratios

4. SEM images of the MgAl₂O₄:Mn synthesized using alumina sources with different α/(α+γ) ratios

5. Photoluminescence emission spectra (λ_ex=365 nm) of the MgAl₂O₄:Mn phosphors using the Al₂O₃ with different α/(α+γ) ratios annealed at 1000 ℃ for 10 h (a), annealed at 1000 ℃ for 10 h and at 1200 ℃ for another 10 h (b), I_{651 nm}/I_{520 nm} ratios calculated from the luminescence spectra of the MgAl₂O₄:Mn phosphors (both as-prepared and post-annealed) (c)

6. XRD pattern (a) and photoluminescence spectrum (λ_ex=365 nm) (b) of the phosphor synthesized at 1550 ℃ for 5 h using Al₂O₃ (AR, γ-phase, micro size) as the alumina source