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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 excitation (a) and emission (b) spectra of YxGd1−xPO4: 5 mol% Eu3+ (x = 0.1, 0.5, 0.9)
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Figure 7: The excitation (a) and emission (b) spectra of YxGd1−xPO4: 5 mol% Eu3+ (x = 0.1, 0.5, 0.9)

Mentions: For the mixed rare earth phosphate YxGd1–xPO4: Eu3+ (x = 0.1, 0.5, 0.9), both excitation and emission spectra are shown in Fig. 7, which have the similar features to the above. It can be observed the CTB band of O2− to Eu3+ (belonging to PO43−, here “2−” is only the formatted charge of O in PO42−), peaking at 253 nm and a sharp absorption band from 8S7/2–6IJ transitions for Gd3+, revealing the existence of the energy transfer process between Gd3+ and Eu3+. The characteristic emissions of Gd3+ are situated at the strong excitation band of YxGd1–xPO4, suggesting that there exists the energy transfer of Gd3+→PO43− → Eu3+, at the same time, the energy level difference in 6GJ and 6PJ of Gd3+ is close to that of 7F1 and 5D0 of Eu3+, a Gd3+ in 6GJ state can excite Eu3+ into 5D0 state by resonance energy transfer, which results in the energy transfer of Gd3+ to Eu3+[39]. Besides this, several strong absorption bands have been observed in the long region of 300–500 nm, which originate from the Eu3+ff transitions. Figure 6B shows the emission spectra of the YxGd1–xPO4: Eu3+ with the different content ratio of Y3+ to Gd3+ ions. The characteristic emission can be seen obviously (5D0 → 7FJ) originating from low energy transfer of Eu3+. Among these emission lines, 5D0 → 7F1 transition is dominant. This indicates that in these hosts, more Eu3+ sites are in inversion symmetry. With the content of Gd increases, the intensity of 5D0 → 7F1 emission increases. Obviously, Gd3+ plays an intermediate role in the energy transfer from PO43− to the activator. The energy transfer process in YxGd1–xPO4: Eu3+ may be described as follows [40]: energy is first absorbed by host absorption band, then is trapped by Gd3+ ions and migrated along them until it is trapped by the activator, resulting in the characteristic luminescence. Certainly, Eu3+ also can obtain energy from host band directly. Besides, it can be seen the luminescent intensity of Y0.9Gd0.1PO4: Eu3+ is weaker than those of other composition, suggesting that the tetragonal phase of Y0.9Gd0.1PO4: Eu3+ is not so favorable as the hexagonal phase of Y0.9Gd0.1PO4: Eu3+ and Y0.9Gd0.1PO4: Eu3+ and the influence of crystal phase on the luminescence is higher than that of water molecules. In addition, either hexagonal phase or tetragonal one cannot show apparent difference in the luminescent intensity of magnetic dipolar transition (5D0 → 7F1) and electronic dipolar transition (5D0 → 7F2).


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

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

The excitation (a) and emission (b) spectra of YxGd1−xPO4: 5 mol% Eu3+ (x = 0.1, 0.5, 0.9)
© Copyright Policy
Related In: Results  -  Collection

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

Figure 7: The excitation (a) and emission (b) spectra of YxGd1−xPO4: 5 mol% Eu3+ (x = 0.1, 0.5, 0.9)
Mentions: For the mixed rare earth phosphate YxGd1–xPO4: Eu3+ (x = 0.1, 0.5, 0.9), both excitation and emission spectra are shown in Fig. 7, which have the similar features to the above. It can be observed the CTB band of O2− to Eu3+ (belonging to PO43−, here “2−” is only the formatted charge of O in PO42−), peaking at 253 nm and a sharp absorption band from 8S7/2–6IJ transitions for Gd3+, revealing the existence of the energy transfer process between Gd3+ and Eu3+. The characteristic emissions of Gd3+ are situated at the strong excitation band of YxGd1–xPO4, suggesting that there exists the energy transfer of Gd3+→PO43− → Eu3+, at the same time, the energy level difference in 6GJ and 6PJ of Gd3+ is close to that of 7F1 and 5D0 of Eu3+, a Gd3+ in 6GJ state can excite Eu3+ into 5D0 state by resonance energy transfer, which results in the energy transfer of Gd3+ to Eu3+[39]. Besides this, several strong absorption bands have been observed in the long region of 300–500 nm, which originate from the Eu3+ff transitions. Figure 6B shows the emission spectra of the YxGd1–xPO4: Eu3+ with the different content ratio of Y3+ to Gd3+ ions. The characteristic emission can be seen obviously (5D0 → 7FJ) originating from low energy transfer of Eu3+. Among these emission lines, 5D0 → 7F1 transition is dominant. This indicates that in these hosts, more Eu3+ sites are in inversion symmetry. With the content of Gd increases, the intensity of 5D0 → 7F1 emission increases. Obviously, Gd3+ plays an intermediate role in the energy transfer from PO43− to the activator. The energy transfer process in YxGd1–xPO4: Eu3+ may be described as follows [40]: energy is first absorbed by host absorption band, then is trapped by Gd3+ ions and migrated along them until it is trapped by the activator, resulting in the characteristic luminescence. Certainly, Eu3+ also can obtain energy from host band directly. Besides, it can be seen the luminescent intensity of Y0.9Gd0.1PO4: Eu3+ is weaker than those of other composition, suggesting that the tetragonal phase of Y0.9Gd0.1PO4: Eu3+ is not so favorable as the hexagonal phase of Y0.9Gd0.1PO4: Eu3+ and Y0.9Gd0.1PO4: Eu3+ and the influence of crystal phase on the luminescence is higher than that of water molecules. In addition, either hexagonal phase or tetragonal one cannot show apparent difference in the luminescent intensity of magnetic dipolar transition (5D0 → 7F1) and electronic dipolar transition (5D0 → 7F2).

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.