Limits...
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 TEM pictures of Y0.1La0.9PO4: 5 mol% Eu3+ (a), Y0.5La0.5PO4: 5 mol% Eu3+ (b), and Y0.9La0.1PO4: 5 mol% Eu3+ (c)
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2991227&req=5

Figure 3: The TEM pictures of Y0.1La0.9PO4: 5 mol% Eu3+ (a), Y0.5La0.5PO4: 5 mol% Eu3+ (b), and Y0.9La0.1PO4: 5 mol% Eu3+ (c)

Mentions: Furthermore, we also have examined the microstructure (particle size and morphology) of the mixed rare earth orthophosphates with the different molar ratio. As shown in Fig. 3, La0.1Y0.9PO4 product (Fig. 3c) is composed with the mixed morphologies of the nanoparticles and nanorods (conglomeration of nanowires), which is consistent with the coexistence of the mixed hexagonal and tetragonal phases. Rare earth orthophosphate with hexagonal phase shows a highly anisotropic structure and is favorable for the crystal growth along a certain direction and form the nanorods or nanowires, while it is contrary to the rare earth phosphate with tetragonal structure to form nanoparticles [37,38]. The actual particle size of these nanophosphors can be estimated to be around 20–80 nm from the measurement of TEM. On the other hand, YxLa1–xPO4 samples with hexagonal phase and monoclinic phase are composed of nanowires. Figure 4 shows the TEM images of the mixed orthophosphates LaxGd1–xPO4 (x = 0.1, 0.5, 0.9), which presents nanowires or nanorods. With the increase in the La3+ content, the ratio of the length to width for the particle is changed. When the molar ratio of Gd3+ is higher than 0.5, nanorods is dominated. On the contrary, the nanowires are preferred. However, it needs to be referred that the products present more uniform morphology of nanorods at the molar ratio of Gd3+: La3+ of 1:1 than at other molar ratios. The actual particle size of these nanophosphors can be estimated to be around 20–50 nm from the measurement of TEM. Figure 5 shows the microstructure of the mixed orthophosphates YxGd1–xPO4 (x = 0.1, 0.5, 0.9). Both Y0.1Gd0.9PO4 and Y0.5Gd0.5PO4 show nanorod morphology. The actual particle size of them can be estimated to be around 50–200 nm from the measurement of TEM. Generally, only tetragonal nanocube can be obtained for YPO4 under such identical conditions, which cannot be observed in the TEM images of Y0.1Gd0.9PO4 and Y0.5Gd0.5PO4 products. This is the evidence that we have synthesized YxGd1–xPO4 instead of the mixture of YPO4 and GdPO4. Besides this, tetragonal Y0.9Gd0.1PO4 presents pure nanocube particle. These phenomena are strongly related to the different ratio of the rare earth ions that have the different ion radii.


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

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

The TEM pictures of Y0.1La0.9PO4: 5 mol% Eu3+ (a), Y0.5La0.5PO4: 5 mol% Eu3+ (b), and Y0.9La0.1PO4: 5 mol% Eu3+ (c)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2991227&req=5

Figure 3: The TEM pictures of Y0.1La0.9PO4: 5 mol% Eu3+ (a), Y0.5La0.5PO4: 5 mol% Eu3+ (b), and Y0.9La0.1PO4: 5 mol% Eu3+ (c)
Mentions: Furthermore, we also have examined the microstructure (particle size and morphology) of the mixed rare earth orthophosphates with the different molar ratio. As shown in Fig. 3, La0.1Y0.9PO4 product (Fig. 3c) is composed with the mixed morphologies of the nanoparticles and nanorods (conglomeration of nanowires), which is consistent with the coexistence of the mixed hexagonal and tetragonal phases. Rare earth orthophosphate with hexagonal phase shows a highly anisotropic structure and is favorable for the crystal growth along a certain direction and form the nanorods or nanowires, while it is contrary to the rare earth phosphate with tetragonal structure to form nanoparticles [37,38]. The actual particle size of these nanophosphors can be estimated to be around 20–80 nm from the measurement of TEM. On the other hand, YxLa1–xPO4 samples with hexagonal phase and monoclinic phase are composed of nanowires. Figure 4 shows the TEM images of the mixed orthophosphates LaxGd1–xPO4 (x = 0.1, 0.5, 0.9), which presents nanowires or nanorods. With the increase in the La3+ content, the ratio of the length to width for the particle is changed. When the molar ratio of Gd3+ is higher than 0.5, nanorods is dominated. On the contrary, the nanowires are preferred. However, it needs to be referred that the products present more uniform morphology of nanorods at the molar ratio of Gd3+: La3+ of 1:1 than at other molar ratios. The actual particle size of these nanophosphors can be estimated to be around 20–50 nm from the measurement of TEM. Figure 5 shows the microstructure of the mixed orthophosphates YxGd1–xPO4 (x = 0.1, 0.5, 0.9). Both Y0.1Gd0.9PO4 and Y0.5Gd0.5PO4 show nanorod morphology. The actual particle size of them can be estimated to be around 50–200 nm from the measurement of TEM. Generally, only tetragonal nanocube can be obtained for YPO4 under such identical conditions, which cannot be observed in the TEM images of Y0.1Gd0.9PO4 and Y0.5Gd0.5PO4 products. This is the evidence that we have synthesized YxGd1–xPO4 instead of the mixture of YPO4 and GdPO4. Besides this, tetragonal Y0.9Gd0.1PO4 presents pure nanocube particle. These phenomena are strongly related to the different ratio of the rare earth ions that have the different ion radii.

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.