Highly efficient and thermally stable single-activator white-emitting phosphor K₂Ca(PO₄)F:Eu²⁺ for white light-emitting diodes

Abstract

Highly efficient and stable white emission is realized in a single-doped K2Ca(PO4)F:Eu2+ phosphor with Eu2+ on both K+ and Ca2+ sites.

Two-Site Occupancy Induced a Broad-Band Emission in Phosphor K2YZr(PO4)3:Eu2+ for White-Light-Emitting Diode Applications

“…Here, E and Q (34000 cm −1 ) means the doped and free Eu 2+ 5d energy level positions, respectively; V is the charge number of 2; n is the coordination number of doped Eu 2+ (12 or 9); E a stands for a constant of 2.0 eV herein; r is the radius of K + ion substituted by an activator. 46 By the values were plugged in, the following results were obtained: E K(1) = 23230 cm −1 (430 nm) and E K(2) = 26256 cm −1 (381 nm). The mismatch of the calculated values may be due to the mismatch of Eu 2+ and K + , which leads to a low-grade distortion of the crystal lattice.…”

“…Thus, two different crystal field strengths are formed, as well as two different red shift degrees. Van Uitert proposed that the red shift degree brought by the crystal field might be evaluated by eq : , Here, E and Q (34000 cm –1 ) means the doped and free Eu 2+ 5d energy level positions, respectively; V is the charge number of 2; n is the coordination number of doped Eu 2+ (12 or 9); E a stands for a constant of 2.0 eV herein; r is the radius of K + ion substituted by an activator . By the values were plugged in, the following results were obtained: E K(1) = 23230 cm –1 (430 nm) and E K(2) = 26256 cm –1 (381 nm).…”

Tuning crystal structure and luminescence of Eu2+-activated LiSr1–xBaxPO4 solid solution for white light-emitting diodes

“…Related spectra for QE measurements are shown in Figure S4. The relationship between QE and decay time can be expressed as 13,37 QE = / 0 (3) where  and  0 are the decay time with and without nonradiative transition, respectively. The increase of lifetime for 470 nm emission ad indicated in Figure 7b is in consistent with the increase of QE value from x = 0.3 to 0.995, which suggests the decrease of nonradiative rate.…”

High Efficiency Emission of Eu2+ Located in Channel and Mg‐Site of Mg2Al4Si5O18 Cordierite and Its Potential as a Bi‐Functional Phosphor toward Optical Thermometer and White LED Application

“…The observed blue shift with temperature is a known phenomenon for Eu 2+ ions and was reported in some inorganic compounds. [ 45,46 ] Daicho et al correlated this behavior with the position changes of the XRD diffraction lines because of the enlargement of cell volume and coordination polyhedrons with a temperature increase. [ 46 ] When the temperature rises, the CIE coordinates are stable up to 175 °C, thenceforth the variation of coordinates up to (0.33, 0.30) at 425 °C is exhibited.…”