An activator’s selective occupation of a host
is of great
significance for designing high-quality white light-emitting diode
phosphors, while achieving a full-spectrum single-phase white light
emission phosphor is challenging. In this study, a boron phosphate
solid-solution Na2Y2(BO3)2–x
(PO4)
x
O:0.005
Bi3+ (NYB2–x
P
x
O:0.005 Bi3+) white phosphor was designed
by selectively occupying Bi3+ activators in the mixed anionic
groups. The substitutes of the anionic unit (BO3)3– by the (PO4)3– unit are supposed to
force part of the Bi3+ ion to enter the Na lattice site,
which produces an intense orange-red emission peaked at 590 nm. In
parallel, spectral tuning from blue to white light and an internal
quantum efficiency of 56.42% was obtained, and the thermal stabile
luminescence intensity remains at 94.2% of the initial intensity after
four heating–cooling cycles from 30 to 210 °C (luminescent
intensity is 83.6% of room temperature (RT) at 150 °C, with excellent
thermal stability and recovery performance). Finally, an excellent
color rendering index (Ra = 90.8 and R9 = 85) was demonstrated for white light-emitting diode devices using
only an NYB1.5P0.5O:0.005 Bi3+ phosphor
and a near-ultraviolet (n-UV) 365 nm LED chip. This work delves into
the different selective occupancy of Bi3+ ions and explores
a new avenue for the design of phosphors for full-spectrum white light
emission.
Mechanoluminescence (ML) materials have found potential applications in information storage, anti‐counterfeiting, and stress sensing. Conventional stress sensing based on absolute ML intensity is prone to significant mistakes owing to the unpredictability of measurement surroundings. However, implementing a ratiometric ML sensing technique may considerably ameliorate this issue. In this study, a single activator‐doped gallate material (LiGa5O8:Pr3+) is proposed to determine the relationship between the ML intensity and the change in local positional symmetry that occurs when the material is subjected to stress. The sensing reliability of the ML intensity ratio under different factors (Force; Content; Thickness and Materials) is systematically analyzed, where the factor that has the greatest effect on the proportional ML is the concentration, with the ML intensity asymmetry ratio decreasing from 1.868 to 1.300 varying concentration at constant stress. The colour‐resolved visualization of stress sensing is further realized, which opens a new path for a ratiometric ML‐based strategy to improve the reliability of stress sensing.
Luminous properties play an essential role in the phosphor-converted white light-emitting diodes for high-quality illumination, where the self-reducing behavior of doped activators and excellent thermal stability have received significant attention....
Mechanical luminescence (ML) is the conversion of mechanical energy into light energy when a material is subjected to a force. It is challenging to develop ML materials with tunable luminescent properties by single ion doping, which have broad application prospects in the fields of stress sensing and dynamic signature anticounterfeiting. In this study, a Pr3+ doped Sr2Ga2GeO7 tunable ML material is reported. Due to the traps resulting from unequal substitution of Pr3+–Sr2+ in [SrO6] heptahedra, the deep/shallow traps redistribution occurs towards a multicolor ML from red to green. In addition, even after continuous friction sliding force (15 N), the ML intensities can be recovered after ultraviolet pre‐irradiation, indicating that Sr2Ga2GeO7: Pr3+ has excellent ML emission stability. Based on thermoluminescence analysis, potential PersL and ML mechanisms are further elaborated by a lattice engineering (trap regulation) strategy. In all, the development of single‐ion doped multicolor ML materials may have crucial research value and show a variety of potential applications in the fields of anticounterfeiting and information encryption.
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