Temperature-Dependent Spectroscopy of Cr3+:YGG Nanophosphors with Multisite Emission

Fig. 1:a) XRD pattern of the synthesized Cr:YGG nanocrystals; The results of the Rietveld analysis b) lattice parameter and average crystalline size, c) dependence of the lattice parameters of both garnet fractions from the concentration of Cr3+ ions. Fig. 3: Diffuse reflectance spectra of the Cr:YGG nanocrystals. Fig. 4: Temperature dependence of Cr3+ excitation bands measured at λem – 710 nm for a) Cr01, b) Cr05, c) Cr1, d) Cr3, e) Cr5, and f) Cr10, respectively. Fig. 5: a) Cr:YGG excitation spectra measured at λem – 710 nm and T – 80K. Temperature dependence of Cr3+ excitation band parameters: b) 4T2g band area; c) ΔFWHM of the 4T2g band; d) λmax of the 4T2g band; e) λmax of the first 4T1g band; f) λmax of the second 4T1g band. Fig. 6: Emission spectra of Cr3+ ions in Cr:YGG nanocrystals measured at λexc – 450 nm and a) T – -190 °C, T – 100 °C. Fig. 7: Temperature dependence of Cr3+ emission for a) Cr0.1, b) Cr0.5, c) Cr1, d) Cr3, e) Cr5, and f) Cr10 measured at λexc – 450 nm. Fig. 8: Temperature dependence of Cr3+ emission band parameters: 4T2g→4A2g a) area; b) ΔFWHM; c) λmax; and 2Eg→4A2g d) R-lines area, d) R1-line ΔFWHM; e) λmax. Fig. 9: Temperature dependence of Cr3+ emission area for Cr:YGG nanopowders. The collected values were normalized on the Cr3+ emission at -190 °C. Fig 10: Excitation spectra of Cr3+ ions in Cr:YGG nanocrystals (Cr10) measured at -190 °C and λem – 710 nm (black line), and λem – 850 nm (red line). Fig. 11: Luminescence lifetime map of Cr3+:YGG nanocrystals measured at λexc – 450 nm.