Thermally stable and color-tunable bi-activated (Dy/Eu) alkaline earth metasilicate phosphor for luminescent devices.

A solid-state reaction methodology has been adopted to synthesize Dy (dysprosium)/Eu (europium) co-activated NaCaSiO (NCMS) phosphors. The structural, morphological, and luminescence characteristics of the prepared materials have been investigated. The phase purity of the material was confirmed by X-ray diffraction (XRD) by comparing the diffraction peaks with the JCPDS standard pattern (JCPDS card no. 75-1687). The photoluminescence (PL) spectra of NCMS phosphors activated with Dy and co-activated with Dy (sensitizer)/Eu (activator) ions were investigated. The as-prepared NCMS phosphors co-activated with Dy/Eu ions were excited with near-ultraviolet light ( = 348 nm) and showed the utmost energy transfer of up to 97.80% from sensitizer to activator. Dexter and Reisfeld's approximation specifically confirms that the energy transfer from sensitizer to activator was through electric dipole-dipole interactions. The Dy-activated NCMS phosphor showed an illumination shift from yellow to red by varying the Eu ion concentration and colour tunability is also observed by altering the excitation energy. The emission intensity was sustained up to 92.21% at 423 K (∼150 °C), indicating an excellent thermal stability of the bi-activated NCMS phosphor. The Dy/Eu co-doped NCMS phosphors display excellent thermal stability with flexible color tunability to emerge as promising contenders in the field of lighting and display technologies.