A series of K3Gd1 x y(PO4)2:xCe3+,yTb3+phosphors are synthesized by the solid-sate reaction method.X-ray diffraction and photoluminescence spectra are utilized to characterize the structures and luminescence properties of the as-synthesized phosphors.Co-doping of Ce3+enhances the emission intensity of Tb3+greatly through an efficient energy transfer process from Ce3+to Tb3+.The energy transfer is confirmed by photoluminescence spectra and decay time curves analysis.The efficiency and mechanism of energy transfer are investigated carefully.Moreover,due to the nonconcentration quenching property of K3Tb(PO4)2,the photoluminescence spectra of K3Tb1 x(PO4)2:xCe3+are studied and the results show that when x=0.11 the strongest Tb3+green emission can be realized.
A novel red-emitting phosphor, CaYAl3O7 : Eu 3+ , Sm3+ , is synthesized by a combustion method at a low temperature (850℃), and the single phase of CaYAl3O7 is confirmed by powder X-ray diffraction measurements. The photoluminescence property results reveal that the red emission intensity of Eu3+ is strongly dependent on the Sm3+ concentration. Only the Eu 3+ luminescence is detected in the Eu 3+ -Sm3+ co-doped CaYAl3O7 phosphor with 393 nm excitation. However, under the characteristic excitation (402 nm) of Sm3+ , not only the Sm3+ emission but also the Eu 3+ emission are observed. A possible mechanism of the energy transfer between Sm3+ and Eu 3+ is investigated in detail.
The structure and photoluminescence (PL) properties of Sr3SiO5 : Sm3+ and Li+-doped Sr3SiO5 : Sm3+ red-emitting phosphors were investigated. Samples were prepared by the high-temperature solid-state method. PL spectra show that the concentration quenching occurs when the Sm3+ concentration is beyond 1.3 mol% in Sr3SiO5 : Sm3+ phosphor without doping Li+ ions. The concentration-quenching mechanism can be explained by the electric dipole-dipole interaction of Sm3+ ions. The incorporation of Li+ ions into Sr3SiO5 : Sm3+ phosphors, as a charge compensator, improves the PL properties. The lithium ions also suppress the concentration quenching in Sm3+ with concentration increased from 1.3 mol% to 1.7 mol%.
Monovalent ions Li+, Na+, and K+, as charge compensators, are introduced into CaYAl3O7: M(M =Eu3+, Ce3+) in this letter. Their crystal phases and photoluminescence properties of different alkali metal ions doped in CaYAl3O7 are investigated. In addition, the influence of charge compensation ion Li+which has a more obvious role in improving luminescence intensity on CaYAl3O7: Eu3+phosphor is intentionally discussed in detail and a possible mechanism of charge compensation is given. The enhancement of red emission centered at 618 nm belonging to Eu3+is achieved by adding alkali metal ion Li+under 393-nm excitation.
