The crystal structure and luminescence properties of novel Ce3+ and Ce3+, Sm3+-activated Y4SiAlO8N phosphors for near-UV white LEDs

Abstract

A series of novel Ce³⁺ and/or Sm³⁺ activated Y₄SiAlO₈N (YSAON) phosphors are successfully synthesized by a conventional solid-state reaction method. The formation of monophasic YSAON is confirmed by X-ray powder diffraction (XRD) analysis. The crystal structure of YSAON is solved by XRD refinement data. DFT calculations indicate that Y₄SiAlO₈N has an indirect band gap of 3.819 eV. Based on the analysis of crystal structure and lifetime curves, four emission sites of YSAON:0.02Ce³⁺ are identified, which are Y1 (413 nm, 448 nm), Y2 (428 nm, 469 nm), Y3 (619 nm, 698 nm) and Y4 (512 nm, 569 nm), respectively. The concentration quenching of Ce³⁺ in YSAON is investigated in detail and it is confirmed to be due to dipole–dipole interactions. Photoluminescence excitation (PLE) and photoluminescence (PL) spectral measurements showed that the Ce³⁺ and Sm³⁺ co-doped phosphor could be efficiently excited by near-UV light, and exhibited four emission bands peaked at 485 nm, 565 nm, 605 nm and 650 nm, respectively. The CIE chromaticity coordinates of the obtained white light can be tuned by adjusting the content of Ce³⁺ and Sm³⁺ ions. Therefore, we anticipate that these materials can be used in near-UV chip pumped white LEDs.