Discovery of novel solid solution Ca3Si3−x O3+x N4−2x : Eu2+ phosphors: structural evolution and photoluminescence tuning

Abstract

Discovery of novel phosphors is one of the main issues for improving the color rendering index (CRI) and correlated color temperature (CCT) of white light-emitting diodes (w-LEDs). This study mainly presents a systematic research on the synthesis, crystal structure variation and photoluminescence tuning of novel (oxy)nitride solid solution Ca3Si3−xO3+xN4−2x: Eu2+ phosphors. XRD refinements show that lattice distortion occurs when x value diverges the optimum one (x = 1). The lattice distortion causes a widening of emission spectrum and an increase of Stokes shift (ΔSS), which leads to a bigger thermal quenching. With decrease of x value, the emission spectrum shows an obvious red-shift from 505.2 to 540.8 nm, which is attributed to the crystal field splitting. The enhanced crystal field splitting also broadens the excitation spectrum, making it possible to serve as the phosphor for near ultraviolet (n-UV) LEDs. A 3-phosphor-conversion w-LED lamp was fabricated with the as-prepared phosphor, which exhibits high CRI (Ra = 85.29) and suitable CCT (4903.35 K). All these results indicate that the Ca3Si3−xO3+xN4−2x: Eu2+ phosphor can serve as the green phosphor for n-UV w-LEDs, with a tunable spectrum by controlling the crystal structure and morphology.

Photoluminescence properties of a Ce3+ doped Sr3MgSi2O8 phosphor with good thermal stability

“…To evaluate the practicability of title phosphor, the quantum efficiency (QE) of the optimal sample Sr 3 MgSi 2 O 8 :0.02Ce 3+ is measured to be 85%, which can be made even higher by improving synthesis conditions. 27 As Fig. 5(a) shows, Ce 3+ doped Sr 3 MgSi 2 O 8 phosphor has strong absorption in the UV region, which matches UV chip very well.…”

Intense Blue Chromophores in Cobalt Doped Phenacite‐Type Zinc Germanate System through Jahn‐Teller Distortion of Co Tetrahedron

“…To further understand the insight of the distortion of these tetrahedrons, the distortion index was calculated according to equation ( 1). [37] Dd ¼…”

“…This also further confirms the substitution of Co 2+ in the Zn1 lattice.However, for x =0.4, there is a sudden change in the bond distance of both, the Co−O bond increases substantially and the Zn1 bond distance decreases significantly. To further understand the insight of the distortion of these tetrahedrons, the distortion index was calculated according to equation 1 [37] …”

Effect of [Ln3+–Si4+] (Ln = Y, La, Gd, Lu) Cosubstitution on the Structure and Luminescence Property of Sr9Mg1.5(PO4)7:Eu2+ Phosphor

“…The analysis of the XRD patterns presented in Figure 1b evidences a slight shift of XRD peaks to higher angles with increasing the [Ln 3þ ÀSi 4þ ] concentration (x), which is due to the fact that the radius of [Ln 3þ þ Si 4þ ] is smaller than that of [Sr 2þ þ P 5þ ]. [13] The ionic radii of Sr 2þ , Eu 2þ , Eu 3þ , P 5þ , Si 4þ , and Ln 3þ ions with different coordination numbers (CN) [14] are listed in Table 1. The ionic radius of Ln 3þ ions is almost in the order of La 3þ > Gd 3þ > Y 3þ > Lu 3þ .…”