Up-conversion luminescence of NaY(WO4)2: Yb, Er under 1550 and 980 nm excitation

•Regular red enhancement wasnt observed by increasing Yb content under 980 nm.•NaY(WO4)2:Yb, Er presents abnormally bright green emission under 1550 nm.•NaY(WO4)2:Yb, Er shows 4 times more intense than NaY(WO4)2:Er under 1550 nm.

Er3+ single-doped and Er3+, Yb3+ co-doped NaY(WO4)2 phosphors were synthesized at 1100 °C by a solid-state reaction method. The samples were characterized by XRD and emission spectral analysis, and the luminescence properties of the phosphors were studied using different excitation sources. The maximum emission intensity of the phosphor was achieved at 24 mol% of the Er3+ ion single-doped under 980 and 1550 nm excitation. The red emission of the phosphor was not changed by increasing Yb3+ ion concentrations, and the material exhibited excellent color purity and color stability. When excited by the 1550 nm laser, the fraction of red emission slightly increased compared with that observed under 980 nm excitation but the main bright green emission. The brightness of Yb3+, Er3+ co-doped NaY(WO4)2 is about 4 times more intense than that of conventional Er3+ single-doped NaY(WO4)2. The UCL mechanisms of the phosphor at 980 and 1550 nm are completely different.

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