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Hydrothermal Synthesis, Microstructure and Photoluminescence of Eu-Doped Mixed Rare Earth Nano-Orthophosphates.

Yan B, Xiao X - Nanoscale Res Lett (2010)

Bottom Line: For La(x)Gd(1-x)PO(4): Eu(3+) system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires.Similarly, Y(x)Gd(1-x)PO(4): Eu(3+), Y(0.1)Gd(0.9)PO(4): Eu(3+) and Y(0.5)Gd(0.5)PO(4): Eu(3+) samples present the pure hexagonal phase and nanorods microstructure, while Y(0.9)Gd(0.1)PO(4): Eu(3+) exhibits the tetragonal phase and nanocubic micromorphology.The photoluminescence behaviors of Eu(3+) in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Tongji University, 200092 Shanghai, China.

ABSTRACT
Eu(3+)-doped mixed rare earth orthophosphates (rare earth = La, Y, Gd) have been prepared by hydrothermal technology, whose crystal phase and microstructure both vary with the molar ratio of the mixed rare earth ions. For La(x)Y(1-x)PO(4): Eu(3+), the ion radius distinction between the La(3+) and Y(3+) is so large that only La(0.9)Y(0.1)PO(4): Eu(3+) shows the pure monoclinic phase. For La(x)Gd(1-x)PO(4): Eu(3+) system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires. Similarly, Y(x)Gd(1-x)PO(4): Eu(3+), Y(0.1)Gd(0.9)PO(4): Eu(3+) and Y(0.5)Gd(0.5)PO(4): Eu(3+) samples present the pure hexagonal phase and nanorods microstructure, while Y(0.9)Gd(0.1)PO(4): Eu(3+) exhibits the tetragonal phase and nanocubic micromorphology. The photoluminescence behaviors of Eu(3+) in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure).

No MeSH data available.


The XRD patterns of YxLa1−xPO4: 5 mol% Eu3+ (a), LaxGd1−xPO4: 5 mol% Eu3+ (b) and YxGd1−xPO4: 5 mol% Eu3+ (c) (x = 0.1, 0.5, 0.9)
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Figure 1: The XRD patterns of YxLa1−xPO4: 5 mol% Eu3+ (a), LaxGd1−xPO4: 5 mol% Eu3+ (b) and YxGd1−xPO4: 5 mol% Eu3+ (c) (x = 0.1, 0.5, 0.9)

Mentions: Li et al. have studied the crystal phase structure of the mixed rare earth phosphates, indicating that pure LaPO4 and YPO4 crystallize in monoclinic phase and tetragonal phase, respectively, while the mixed phosphate of La0.5Y0.5PO4 belongs to the hexagonal phase [36]. However, the crystal phase structure of the mixed orthophosphates YxLa1–xPO4 (x = 0.1, 0.5, 0.9) can be changed with different molar ratio of Y3+ to La3+, whose XRD pattern of mixed orthophosphates is shown in Fig. 1a. The change of the XRD pattern for YxLa1–xPO4 (Fig. 1a) depending on the Y:La molar ratio is well known as analyzed as typical solid solution. With the decrease in yttrium ion content, the tetragonal phase cannot be observed and the monoclinic phase appears. With La3+ to Y3+ of 9:1 M ratio, the product shows the pure monoclinic phase, just like the pure LaPO4. The final product La0.1Y0.9PO4: Eu3+ presents the mixture of hexagonal LaPO4 and tetragonal YPO4 for they cannot form the solid solution. As for LaxGd1–xPO4 (x = 0.1, 0.5, 0.9), the mixed rare earth phosphates LaxGd1–xPO4 (x = 0.1, 0.5) have the similar pure hexagonal phase, while La0.9Gd0.1PO4 belongs to the pure monoclinic phase (Fig. 1b). The XRD patterns of the mixed YxGd1–xPO4 (x = 0.1, 0.5, 0.9) are shown in Fig. 1c. The mixed rare earth phosphates YxGd1–xPO4 (x = 0.1 and 0.5) show the hexagonal phase with the different peak intensities. On the base of the literatures, the GdPO4 powders in most cases have been reported to have the pure hexagonal phase. Besides, the ion radii of Y3+ and Gd3+ are 88 pm and 93.8 pm, respectively, so the replacement of Gd3+ by Y3+ cannot have an influence on the final crystal phase structure of the product until the content of Y3+ reaches 0.9 mol. With the 1:9 M ratio of Gd3+ and Y3+, Y0.9Gd0.1PO4 present to the pure tetragonal phase. In one word, because the ion radii of Y3+, Gd3+ and La3+ are 88, 93.8 and 106.1 pm, respectively, the radii difference between rare earth ions strongly affects the crystal phase and microstructure the mixed rare earth phosphates. The difference in radius between Y3+ and La3+ is so large that it is not easy to form the product of the single phase. Additionally, the difference in radius between La3+ and Gd3+ (Gd3+ and Y3+) is smaller than that of Y3+ and La3+, so the product can present the pure phase with the different content ratio of the rare earth ions. Besides, the calculated grain sizes of these samples are in the range of 12–40 nm using Scherrer’s equation, which delegates the dimension in the normal direction of (111) plane.


Hydrothermal Synthesis, Microstructure and Photoluminescence of Eu-Doped Mixed Rare Earth Nano-Orthophosphates.

Yan B, Xiao X - Nanoscale Res Lett (2010)

The XRD patterns of YxLa1−xPO4: 5 mol% Eu3+ (a), LaxGd1−xPO4: 5 mol% Eu3+ (b) and YxGd1−xPO4: 5 mol% Eu3+ (c) (x = 0.1, 0.5, 0.9)
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Figure 1: The XRD patterns of YxLa1−xPO4: 5 mol% Eu3+ (a), LaxGd1−xPO4: 5 mol% Eu3+ (b) and YxGd1−xPO4: 5 mol% Eu3+ (c) (x = 0.1, 0.5, 0.9)
Mentions: Li et al. have studied the crystal phase structure of the mixed rare earth phosphates, indicating that pure LaPO4 and YPO4 crystallize in monoclinic phase and tetragonal phase, respectively, while the mixed phosphate of La0.5Y0.5PO4 belongs to the hexagonal phase [36]. However, the crystal phase structure of the mixed orthophosphates YxLa1–xPO4 (x = 0.1, 0.5, 0.9) can be changed with different molar ratio of Y3+ to La3+, whose XRD pattern of mixed orthophosphates is shown in Fig. 1a. The change of the XRD pattern for YxLa1–xPO4 (Fig. 1a) depending on the Y:La molar ratio is well known as analyzed as typical solid solution. With the decrease in yttrium ion content, the tetragonal phase cannot be observed and the monoclinic phase appears. With La3+ to Y3+ of 9:1 M ratio, the product shows the pure monoclinic phase, just like the pure LaPO4. The final product La0.1Y0.9PO4: Eu3+ presents the mixture of hexagonal LaPO4 and tetragonal YPO4 for they cannot form the solid solution. As for LaxGd1–xPO4 (x = 0.1, 0.5, 0.9), the mixed rare earth phosphates LaxGd1–xPO4 (x = 0.1, 0.5) have the similar pure hexagonal phase, while La0.9Gd0.1PO4 belongs to the pure monoclinic phase (Fig. 1b). The XRD patterns of the mixed YxGd1–xPO4 (x = 0.1, 0.5, 0.9) are shown in Fig. 1c. The mixed rare earth phosphates YxGd1–xPO4 (x = 0.1 and 0.5) show the hexagonal phase with the different peak intensities. On the base of the literatures, the GdPO4 powders in most cases have been reported to have the pure hexagonal phase. Besides, the ion radii of Y3+ and Gd3+ are 88 pm and 93.8 pm, respectively, so the replacement of Gd3+ by Y3+ cannot have an influence on the final crystal phase structure of the product until the content of Y3+ reaches 0.9 mol. With the 1:9 M ratio of Gd3+ and Y3+, Y0.9Gd0.1PO4 present to the pure tetragonal phase. In one word, because the ion radii of Y3+, Gd3+ and La3+ are 88, 93.8 and 106.1 pm, respectively, the radii difference between rare earth ions strongly affects the crystal phase and microstructure the mixed rare earth phosphates. The difference in radius between Y3+ and La3+ is so large that it is not easy to form the product of the single phase. Additionally, the difference in radius between La3+ and Gd3+ (Gd3+ and Y3+) is smaller than that of Y3+ and La3+, so the product can present the pure phase with the different content ratio of the rare earth ions. Besides, the calculated grain sizes of these samples are in the range of 12–40 nm using Scherrer’s equation, which delegates the dimension in the normal direction of (111) plane.

Bottom Line: For La(x)Gd(1-x)PO(4): Eu(3+) system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires.Similarly, Y(x)Gd(1-x)PO(4): Eu(3+), Y(0.1)Gd(0.9)PO(4): Eu(3+) and Y(0.5)Gd(0.5)PO(4): Eu(3+) samples present the pure hexagonal phase and nanorods microstructure, while Y(0.9)Gd(0.1)PO(4): Eu(3+) exhibits the tetragonal phase and nanocubic micromorphology.The photoluminescence behaviors of Eu(3+) in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure).

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Tongji University, 200092 Shanghai, China.

ABSTRACT
Eu(3+)-doped mixed rare earth orthophosphates (rare earth = La, Y, Gd) have been prepared by hydrothermal technology, whose crystal phase and microstructure both vary with the molar ratio of the mixed rare earth ions. For La(x)Y(1-x)PO(4): Eu(3+), the ion radius distinction between the La(3+) and Y(3+) is so large that only La(0.9)Y(0.1)PO(4): Eu(3+) shows the pure monoclinic phase. For La(x)Gd(1-x)PO(4): Eu(3+) system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires. Similarly, Y(x)Gd(1-x)PO(4): Eu(3+), Y(0.1)Gd(0.9)PO(4): Eu(3+) and Y(0.5)Gd(0.5)PO(4): Eu(3+) samples present the pure hexagonal phase and nanorods microstructure, while Y(0.9)Gd(0.1)PO(4): Eu(3+) exhibits the tetragonal phase and nanocubic micromorphology. The photoluminescence behaviors of Eu(3+) in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure).

No MeSH data available.