Realizing Broad Color Tunability and Enhanced Thermal Stability via Energy Transfer in Ce³⁺, Eu²⁺-Codoped Ca-α-Sialon Phosphors

Luminescent properties of phosphors can be modified and improved by constructing energy transfer. In this article, a series of Ce³⁺- and/or Eu²⁺-doped Ca-α-sialon phosphors were synthesized through the traditional solid-state reaction method. The construction of an efficient energy transfer enables the modulation of a wide range of light colors, thereby facilitating a gradual color change from blue-green (0.1844, 0.2535) to yellow (0.4282, 0.5051). Moreover, the codoping of Ce³⁺ enhances the luminescence intensity of Eu²⁺ by approximately 2.2 times. Within the experimental gradient, the energy-transfer efficiency can reach up to 58.7%, and the energy-transfer mechanism is a quadrupole-quadrupole interaction. Gaussian fitting of the emission spectrum of the codoped samples reveals that the intensities of the Eu²⁺ and Ce³⁺ emission peaks of the codoped samples at 423 K are 78 and 87% of those at room temperature, respectively. Moreover, the thermal stability of the characteristic peaks of Ce³⁺ in the codoped samples is significantly enhanced compared to those doped alone. These excellent properties highlight the potential application of CaSi₉Al₃ON₁₅/Ce³⁺, Eu²⁺ phosphor in white light WLEDs.