The self‐reduction synthesis and luminescent properties of Eu²⁺/Eu³⁺ activated BaZr_xSi₃O_7+2x phosphors with white light emission for white light‐emitting diodes

Abstract

The BaZrxSi3O7+2x:Eu2+/Eu3+ (2%, molar ratio) phosphors were prepared with adding different amounts of zirconium dioxide (ZrO2) (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) by a self‐reduction method under air conditions. X‐ray diffraction, photoluminescence properties, thermal quenching properties and luminescent lifetimes of the prepared samples were systematically analyzed. In BaZrxSi3O7+2x:Eu2+/Eu3+, both the 4f → 5d transitions of Eu2+ and sharp emissions assigned to 5D0 → 7FJ (J = 0, 1, 2, 3, 4) transitions of Eu3+ were observed. In addition, the results also reveal that the amount of ZrO2 affects the crystal structure, the self‐reduction process and further influences the relative intensity of Eu2+/Eu3+ in all samples. Therefore, the diverse emission colors can be obtained and modulated by controlling the content of ZrO2. The highlight of this work is that the white light emission is observed, when x is 0.4, 0.6, 0.8 and 1, respectively.

Ca[B8O11(OH)4] : Eu2+ – A Highly Efficient Deep Blue‐Emitting Phosphor Prepared by Low‐Temperature Self‐reduction

“…The self‐reduction method for preparing phosphors shows the advantages of being cheaper, safer and more convenient. The self‐reduction method requires special crystals, including borates (SrB 4 O 7 : Eu, [29] SrB 6 O 10 : Eu, BaB 8 O 13 : Eu, [30] CaB 2 O 4 : Eu, [31] and Sr 2 B 5 O 9 Cl : Eu [32] ), aluminates (BaAl 2 O 4 : Eu, [25] BaMgAl 10 O 17 : Eu [33] ), silicates (BaMgSiO 4 : Eu, [34] BaZr x Si 3 O 7+2x : Eu, [35] BaSn x Si 3 O 7+2x : Eu [36] and BaZnSiO 4 : Eu [37] ), aluminosilicates (CaAl 2 Si 2 O 8 : Eu, [38] SrAl 2 Si 2 O 8 : Eu, [39] CaAl 2 Si x O 2x+4 : Eu, [40] and CsAlSi 2 O 6 : Eu [41] ) and phosphates (NaCaPO 4 : Eu, [42] Sr 5 (PO 4 ) 3 Cl : Eu [43] and α‐Ca 3 (PO 4 ) 2 : Eu [44] ). Four necessary conditions for the self‐reduction of Eu 3+ to Eu 2+ have been put forward [41,45] .…”