Effect of Yb3+ concentration on the green-yellow upconversion emission of SrGe4O9:Er3+ phosphors

Influence of Cr3+ on yellowish‐green UC emission and energy transfer of Er3+/Cr3+/Yb3+ tri‐doped zinc silicate glasses

“…The CIE 1931 (x; y) chromaticity coordinates for the UC emissions of SZNL‐0Er2Cr2Yb, SZNL‐0.1Er0Cr2Yb, SZNL‐0.1Er1Cr2Yb, SZNL‐0.1Er2Cr2Yb, SZNL‐0.1Er3Cr2Yb, SZNL‐0Er4Cr2Yb, and SZNL‐0.1Er5Cr2Yb glass samples were calculated in correspondence to the coordinates P1.1 (0.296; 0.504), P1.2 (0.341; 0.642), P1.3 (0.318; 0.606), P1.4 (0.312; 0.589), P1.5 (0.307; 0.562), and P1.6 (0.301; 0.554). The CIE 1931 (x; y) chromaticity coordinates of these UC emissions were identified in the yellowish‐green color region 42 . With increasing concentration of Cr 3+ from 0 up to 5 mol.%, the CIE 1931 (x; y) chromaticity coordinates for the UC emission of Er 3+ /Cr 3+ /Yb 3+ tri‐doped gradually moved 34,41,42 and were eventually located in the central position of the yellowish‐green color region 42 .…”

“…By using Zolix Color Convert software, 33 the CIE 1931 (x; y) chromaticity coordinates 34,42 for the UC emissions of Cr 3+ /Yb 3+ co‐doped; Er 3+ /Yb 3+ co‐doped and Er 3+ /Cr 3+ /Yb 3+ tri‐doped SZNL zinc silicate glasses were also calculated and are shown in Figure 6(C). The CIE 1931 (x; y) chromaticity coordinates for the UC emissions of SZNL‐0Er2Cr2Yb, SZNL‐0.1Er0Cr2Yb, SZNL‐0.1Er1Cr2Yb, SZNL‐0.1Er2Cr2Yb, SZNL‐0.1Er3Cr2Yb, SZNL‐0Er4Cr2Yb, and SZNL‐0.1Er5Cr2Yb glass samples were calculated in correspondence to the coordinates P1.1 (0.296; 0.504), P1.2 (0.341; 0.642), P1.3 (0.318; 0.606), P1.4 (0.312; 0.589), P1.5 (0.307; 0.562), and P1.6 (0.301; 0.554).…”

“…Besides, a cross‐relaxation (CR) process 11,42 between two neighboring Er 3+ ions ([ 2 H 11/2 ‐ 4 I 11/2 ] and [ 4 I 11/2 ‐ 4 I 15/2 ]), as well as the ET process from the 4 F 5/2 → 4 F 7/2 transition of Yb 3+ to the 4 I 11/2 → 4 I 15/2 transition of Er 3+ : (ET 4 ): 2 F 5/2 (Yb 3+ ) + 4 I 15/2 (Er 3+ ) → 2 F 7/2 (Yb 3+ ) + 4 I 11/2 (Er 3+ ) 11,14 may occur. Consequently, the green UC emission intensity of Er 3+ becomes stronger.…”

“…To investigate the effects of the increasing molar concentration of Er 3+ for the CIE 1931 (x; y) chromaticity coordinates of UC emissions of Er 3+ /Cr 3+ /Yb 3+ tri‐doped SZNL zinc silicate glasses, we have calculated the CIE 1931 (x; y) chromaticity coordinates using Zolix Color Convert software 34,42 . Detailed calculation results are shown in Figure 9.…”

“…The CIE 1931 (x; y) chromaticity coordinates of these UC emissions were identified in the yellowish‐green color region 42 . With increasing concentration of Cr 3+ from 0 up to 5 mol.%, the CIE 1931 (x; y) chromaticity coordinates for the UC emission of Er 3+ /Cr 3+ /Yb 3+ tri‐doped gradually moved 34,41,42 and were eventually located in the central position of the yellowish‐green color region 42 . Figure 6(C) suggests that the simultaneous increasing intensity of the green UC emission and decreasing intensity of the red UC emission of Er 3+ /Cr 3+ /Yb 3+ tri‐doped have contributed to this movement.…”