Sunday, February 12, 2012

Synthesis and luminescent properties of Ln3+ (Ln3+ = Eu3+, Dy3+) –doped Bi2ZnB2O7 phosphors

Melilites, with the general formula A2XZ2O7, are a series of significant compounds expected as excellent hosts for luminescent materials. Recently, the luminescent properties of Sm3+-doped Bi2ZnB2O7 were investigated, Eu3+ and Dy3+ ion-activated Bi2ZnB2O7 were prepared by a solid-state reaction and the structural character and photoluminescent properties of these phosphors were studied.

The new phosphors Bi2ZnB2O7: Ln3+ (Ln3+ = Eu3+, Dy3+) were synthesized by solid-state reaction technique. The obtained phosphors were investigated by means of X-ray powder diffraction (XRD), photoluminescence excitation and emission spectra with the aim of enhancing the fundamental knowledge about the luminescent properties of Eu3+ and Dy3+ ions in the Bi2ZnB2O7 host lattice. XRD analysis shows that all these compounds are of a single phase of Bi2ZnB2O7.

The photoluminescent emission spectra of Bi2ZnB2O7:Eu3+ phosphor exhibit a well-known characteristic Eu3+ emission and the dominant photoluminescent excitation line is around 465 nm due to the 7F0→5D2 transition. The emission spectra of Bi2ZnB2O7:Dy3+ phosphor show three bands centered at 482, 576 and 667 nm that originate from the transitions of 4F9/26H15/2, 4F9/26H13/2 and 4F9/26H11/2 of Dy3+, respectively. The excitation spectra have several sharp lines in the range of 250~520 nm corresponding to the transitions from the ground state of Dy3+ (6H15/2) to different excitation levels



The excitation and emission spectra of Bi2ZnB2O7: Ln3+ (Ln3+ = Eu3+, Dy3+) at room temperature show the typical 4f-4f transitions of Eu3+ and Dy3+, respectively. The hypersensitive transitions of 5D07F2 (Eu3+) and 4F9/2 6H13/2

(Dy3+) are relatively higher than those of the insensitive transitions in Bi2ZnB2O7. It is conceivable that the Bi2ZnB2O7 structure provides asymmetry sites for activators (Eu3+, Dy3+). The optimum concentrations of Eu3+ and Dy3+ ions in

Bi2ZnB2O7 phosphors are both x =0.05.



Emission spectrum of (Bi1-xEux)2ZnB2O7 (x = 0.01, 0.03, 0.05, 0.07, 0.09) under 465 nm excitation


Reference.

Zhang, Q., Wang, J., Ni, H. Wang, L.(2012) Synthesis and luminescent properties of Ln3+ (Ln3+ = Eu3+, Dy3+) –doped Bi2ZnB2O7 phosphors Rare Metals. 1001-052. Vol. 31. P.35.


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