UV-excited blue- to green-emitting Tb -activated sodium calcium metasilicate colour tunable phosphor for luminescence devices.

Tb -doped Na Ca Si O (NCMS:Tb ) phosphors were synthesized using a solid-state reaction route with increasing dopant concentration. The phase identification studies for NCMS:Tb 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 Na Ca Si O compound. The morphology and size of particles were illustrated from scanning electron microscope (SEM) micrographs. The photoluminescence excitation (PLE) spectrum of Tb -doped Na Ca Si O 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 Tb 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 Tb -activated as-synthesized NCMS phosphor. These results demonstrated that the Tb -activated sodium calcium metasilicate phosphor has immense potential to contribute as a green- and blue-green-emitting component in lighting and display device applications.