A new type of white phosphor Na₂Ca₂Si₃O₉:Dy³⁺ under near-UV light excitation

Phosphor conversion white light emitting diodes (pc-WLEDs) can be fabricated by developing white phosphors under near-UV light excitation. The purpose of this work is to design and prepare a new type of blue phosphor Na₂Ca₂Si₃O₉:Dy³⁺. Under 350 nm excitation, the powdered product Na₂Ca₂Si₃O₉:xDy³⁺ sintered at 950 °C will generate two emission peaks at around 482 nm and 576 nm, which originate from the ⁴F_9/2 → ⁶H_15/2 and ⁴F_9/2 → ⁶H_13/2 transitions of Dy³⁺, respectively. About x = 0.20 of Dy³⁺ is required to achieve optimal dopant concentrations, and further increasing x will led to concentration quenching due to the quadrupole‒quadrupole interactions. The phosphor Na₂Ca₂Si₃O₉:0.20Dy³⁺ shows CIE chromaticity coordinates of (0.3132, 0.3483) excited at 350 nm, falling in the white region. Furthermore, temperature dependent luminescence studies show that the emission intensity of Na₂Ca₂Si₃O₉:0.20Dy³⁺ remains 50% of its 25 °C intensity at 125 °C. According to these results, the phosphor Na₂Ca₂Si₃O₉:0.20Dy³⁺ can be used for WLED lamps with white light emission.