Sulfate Exchange of the Nitrate-Type Layered Hydroxide Nanosheets of Ln2(OH)5NO3·nH2O for Better Dispersed and Multi-color Luminescent Ln2O3 Nanophosphors (Ln = Y0.98RE0.02, RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm)

Table 1 Optical properties of the (Y_0.98RE_0.02)₂O₃ nanophosphors

RE	Main PLE band (nm)	Main PL band (nm)	CIE coordinates (x,y)	Emission color	Lifetime
Pr	280, 4f² → 4f¹5d¹	645,¹D₂ → ³H₄	(0.639,0.303)	Deep red	160 ± 13 ns
Sm	407, ⁶H_5/2 → ⁴K_11/2	609, ⁴G_5/2 → ⁶H_7/2	(0.538,0.414)	Orange	1.52 ± 0.01 ms
Eu	250, CTB (O^2- → Eu³⁺)	613, ⁵D₀ → ⁷F₂	(0.640,0.329)	Orange red	2.71 ± 0.02 ms
Tb	275, 4f⁸ → 4f⁷5d¹	545, ⁵D₄ → ⁷F₅	(0.321,0.551)	Green	3.08 ± 0.02 ms
Dy	350, ⁶H_15/2 → ⁶P_7/2	573, ⁴F_9/2 → ⁶H_13/2	(0.457,0.492)	Yellow	229 ± 12 ns
Ho	449, ⁵I₈ → ⁵F₁	551, ⁵S₂ → ⁵I₈	(0.308,0.657)	Green	126 ± 9 ns
Er	380, I_15/2 → ⁴G_11/2	564, ⁴S_3/2 → ⁴I_15/2	(0.281,0.675)	Green	246 ± 15 ns
Tm	360, ³H₆ → ¹D₂	453, ¹D₂ → ³F₄	(0.194,0.206)	Blue	170 ± 13 ns