UV‐excited blue‐ to green‐emitting Tb3+‐activated sodium calcium metasilicate colour tunable phosphor for luminescence devices

Tb³⁺ -doped Na₄ Ca₄ Si₆ O₁₈ (NCMS:Tb³⁺ ) phosphors were synthesized using a solid-state reaction route with increasing dopant concentration. The phase identification studies for NCMS:Tb³⁺ phosphors were carried out using an X-ray diffraction (XRD) technique. The XRD patterns for the as-synthesized phosphors showed satisfactory agreement with the standard pattern (JCPDS card no. 75-1687) for the pure phase of the Na₄ Ca₄ Si₆ O₁₈ compound. The morphology and size of particles were illustrated from scanning electron microscope (SEM) micrographs. The photoluminescence excitation (PLE) spectrum of Tb³⁺ -doped Na₄ Ca₄ Si₆ O₁₈ phosphor depicts the strong excitation peak obtained in the UV spectral region. The trivalent terbium-activated NCMS phosphors excited in the UV region (232 nm wavelength) exhibited intense emission in the blue (350-470) and green (470-650) spectral regions. When increasing the concentration of Tb³⁺ ions in the host matrix, the emission colour shifted from the blue to the green region due to cross-relaxation energy transfer (CRET) mechanisms and showed the tunable behaviour of the Tb³⁺ -activated as-synthesized NCMS phosphor. These results demonstrated that the Tb³⁺ -activated sodium calcium metasilicate phosphor has immense potential to contribute as a green- and blue-green-emitting component in lighting and display device applications.