Improvement of the thermal stability of bluish-cyan emitting phosphor Y2MgAl4SiO12:Eu2+ using substitution cations (Zn, Ca, Sr) for white LEDs

Abstract

A series of bluish-cyan color adjustable phosphors Y₂MgAl₄SiO₁₂:xEu²⁺(YMAS) and Y₂(Mg_1−y,M_y)Al₄SiO₁₂:Eu²⁺ (M = Zn, Ca, Sr) were synthesized by the solid-state method. The thermal stability can be improved by modifying the cation, especially the thermal stability of Y₂MgAl₄SiO₁₂:Eu²⁺ at 150 °C gradually improved to 92.34% of the original luminescence intensity by introducing Sr²⁺. The white light emitting diode (LED) was fabricated by combining near ultraviolet (NUV) LED chip (370 nm) with a mixture of Y₂Mg_0.8Sr_0.2Al₄SiO₁₂:0.01Eu²⁺ along with green (Ba,Sr)₂SiO₄:Eu and red CaSiAlN₃:Eu in different proportions. A bright warm white LED gives a high color rendering index R_a = 96.4, a low correlated color temperature CCT = 4434 K, and CIE chromaticity coordinates at (0.35, 0.34). The results demonstrate that Y₂Mg_0.8Sr_0.2Al₄SiO₁₂:Eu²⁺ phosphor has potential application in the field of white LEDs.