The object of this study is to synthesize Li 3 Ba 2 Gd 3 (MoO 4 ) 8 doped with Eu 3+ ions and prepared with solidstate reaction technology. The results show that the dominant emission peak of Li 3 Ba 2 Gd 3-x (MoO 4 ) 8 :Eu x phosphor is 5 D 0 f 7 F 2 (614 nm). The intensity of the emission from 5 D 0 to 7 F 2 is 3.8 times higher than that of commercial phosphors, ZnS:(Mn 2+ ,Te 2+ ) when the Eu 3+ concentration is x ) 2.4. The CIE chromaticity coordinates of the red emission of the Li 3 Ba 2 Gd 0.6 Eu 2.4 (MoO 4 ) 8 phosphor are (0.67, 0.33), which is the NTSC system standard for red chromaticity. Because there are two regions in the excitation spectra of Li 3 Ba 2 Gd 3 (MoO 4 ) 8 :Eu 3+ phosphor, one is assigned from the charge-transfer state (CTS) band at about 320 nm, and the other is from the intra-4f transitions from 350 to 500 nm. Hence, the phosphors could be strongly excited by near-UV and blue LED in solid-state lighting technology. The analysis of the lifetime, decay curves, and efficiency of the 5 D 0 f 7 F 2 emission indicates the weak energy transfer between Eu 3+ pairs. The temperature dependence PL and absorption spectra study shows that thermal quenching behavior can be attributed to crossover from the 5 D 0 excited state to the CTS band.

Color-tunable phosphors of BaY2−xEuxZnO5 (x=0.001–0.9) were synthesized using a vibrating milled solid state reaction. The results indicate that the emission spectra of BaY2−xEuxZnO5 samples excited at 395 nm exhibit a series of shaped peaks assigned to the D50→F7J (J=0,1,2,3,4) transitions. Luminescence from the higher excited states, such as D51, D52, and D53, were also observed even though the Eu3+ concentration was up to x=0.2. The chromaticity coordinate of BaY2−xEuxZnO5 phosphors varies with the Eu3+-doped concentrations from blue, white, to red, and which may be potentially applicable as a white light emitting phosphor for ultraviolet light emitting diodes.

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Ba 1−y Sr y La 2−x ZnO 5 :xEu ͑x = 0-1, y = 0-0.7͒ was prepared by the vibrating milled solid-state reaction, and the photoluminescence properties were investigated. The results show that the optimum emission intensity is at y = 0.5 for serial BaLa 2−x ZnO 5 :xEu phosphors under near-UV light excitation ͑394 nm͒ and the CIE chromaticity coordinate is located at ͑0.624, 0.376͒. Furthermore, Sr 2+ doping for serial Ba 1−y Sr y La 1.5 Eu 0.5 ZnO 5 ͑y = 0-0.7͒ phosphors were also investigated; photoluminescence properties indicated that increasing Sr 2+ content enhances not only the emission intensity ratio of 5 D 0 → 7 F 2 transition ͑red emission͒ to 5 D 0 → 7 F 1 transition ͑orange emission͒ but also the emission intensity of 5 D 0 → 7 F 2 transition. The color purity enhancement results from the relatively lower symmetry environment around Eu 3+ ions. The Ba 0.3 Sr 0.7 La 1.5 Eu 0.5 ZnO 5 phosphors have optimal integrated emission intensity, which is 62% larger than the integrated emission intensity of BaLa 1.5 Eu 0.5 ZnO 5 phosphors, and the CIE chromaticity coordinate ͑x, y͒ of Ba 0.3 Sr 0.7 La 1.5 Eu 0.5 ZnO 5 phosphor is ͑0.633, 0.367͒ under near-UV light excitation.Oxide phosphors recently gained much attention for applications such as screens in plasma display panels, 1,2 field-emission displays, 3 and for white light-emitting diodes ͑LEDs͒ 4 because of their higher chemical stability and resistance to moisture relative to that of sulfide phosphors. At present, the most common and convenient method to obtain white light is by combining a yellow-emitting phosphor with an InGaN blue LED chip. 5 However, there are problems for such "blue + yellow" white LEDs, such as a lower colorrendering index. 6 To obtain a higher efficiency white LED with an appropriate color temperature and a higher color-rendering index, an approach using a long wavelength UV III-nitride LED chip coated with blue/green/red tricolor phosphors was introduced. 7-9 Recently, high efficiency UV-LED based on III-nitride compound semiconductors was demonstrated, 10-17 and this can provide a lighting source for UV-LED converted phosphors for solid-state lighting.The Eu 3+ ion is very useful as an activator not only for commercial red phosphors but also for solid-state chemistry. Due to its high sensitivity to the chemical environment, we can obtain information about this around a Eu 3+ ion in a compound by measuring its optical properties. This is because the 5 D 0 → 7 F 2 transition ͑red emission͒ of Eu 3+ ⌬J = 2 is hypersensitive, and the intensity can vary by orders of magnitude, depending on the local environment. However, the magnetic dipole 5 D 0 → 7 F 1 transition ͑orange emission͒ is insensitive to the site symmetry because it is parity-allowed. 18 The better color purity of Eu-doped phosphors can be obtained from the more distorted lattice and relatively low crystal symmetry around the Eu 3+ ion.The BaLa 2 ZnO 5 compound has a tetragonal space group I4/mcm. The structure consists of ZnO 4 tetrahedra with 10-fold coordinated bicapped squ...