Structural and spectroscopic analysis of K₂Y(WO₄)(PO₄):Sm³⁺,Tb³⁺ phosphors for optical applications

A series of singly and co-doped K₂Y(WO₄)(PO₄):Sm³⁺,Tb³⁺ (KYWP) phosphors were synthesized by solid-state reaction (SSR) route, and its photoluminescence (PL) behavior in visible region have been studied. The compound K₂Y(WO₄)(PO₄) formed by combination of tetrahedral anions such as WO₄ and PO₄ are good hosts for phosphor due to their easy-synthesis procedure, low-cost, chemical stability and thermal-stabilities over a wide range of temperatures. X-ray diffraction pattern confirms the orthorhombic crystal system with a space group of Ibca No. (73). SEM, EDS and Elemental mapping confirm the morphology and constituent of elements present in as prepared sample. Under 404 nm excitation, the dominant emission for Sm³⁺ doped K₂Y(WO₄)(PO₄) obtained at 604 nm corresponds to the ⁴G_5/2 → ⁶H_7/2 transition. For Tb³⁺ ions, emissions obtained at 546 nm attributed to ⁵D₄ → ⁷F₆ for the excitation of 377 nm. The Sm³⁺ and Tb³⁺ co-doped K₂Y(WO₄)(PO₄) samples give intense orange-red light when excited at 404 nm, with the optimal concentration of 2 mol% and 5 mol% of Sm³⁺ and Tb³⁺ ions respectively. Also, the intense green color is observed at 377 nm excitation for 2 mol% of Sm³⁺ and Tb³⁺ ion doping. The color coordinates of prepared samples were also clearly displayed in this work. The results indicate that ET between sensitizer and activator (Tb³⁺ ↔ Sm³⁺) is beneficial to improve the luminescence properties of activator (Sm³⁺ and Tb³⁺). All these results confirm the promising application of as prepared phosphors for light emitting diodes, colour tunable phosphor and other opto-electronic devices.