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Novel Pr 3+ , Ho 3+ , and Er 3+ single-doped Ca X Sr Y Ba 1−X−Y WO 4 phosphors were successfully prepared via a facile hydrothermal method. The hydrothermal process was conducted in aqueous condition without the use of any organic solvent, surfactant, or catalyst. The effects of doping-host composition and RE 3+ doping concentration on the emission intensity were investigated to optimize the luminescent properties of Ca X Sr Y Ba 1−X−Y WO 4 :RE 3+ phosphors. Experimental results demonstrate that the morphologies of the products vary gradually and regularly with the change of the host composition, in which the anisotropic growth played a key role. Moreover, the down-conversion emissions of Pr 3+ , Ho 3+ , and Er 3+ in Ca X Sr Y Ba 1−X−Y WO 4 host were successfully realized. After optimizing the luminescent properties, Ca 0.4 Sr 0.6 WO 4 :0.01Pr 3+ , Ca 0.8 Sr 0.2 WO 4 :0.01Ho 3+ , and Ca 0.6 Sr 0.4 WO 4 :0.005Er 3+ exhibited optimal luminescent property, with orange, yellowish-green, and green emissions, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Eu3+ and Tb3+ co-doped NaLa(MoO4)2 phosphors with various shapes have been synthesized by a simple conventional hydrothermal method. The morphology of the materials was found to be manipulated by changing the pH value of the precursor hydrothermal media. Uniform NaLa(MoO4)2 3D microspheres could be trapped at pH 5 and the spindle-like NaLa(MoO4)2 microstructures were obtained at pH 7. When the pH value was adjusted to 9, the flower-like NaLa(MoO4)2 microstructures were obtained. The luminescent properties of the NaLa(MoO4)2:Eu3+/Tb3+ samples with different morphologies prepared at different starting pH values were studied. The results show that the emission intensity of the product obtained at pH 5 is the strongest. Besides, under ultraviolet excitation the luminescence colors of NaLa(MoO4)2 samples co-doped with Eu3+ and Tb3+ can be tuned from red, through yellow and green–yellow, to green by simply adjusting the relative doping concentrations of the activator ions. This merit of multicolor emissions in the visible region endows the as-prepared products with potential application in the fields of light-display systems and optoelectronic devices. [Copyright &y& Elsevier]

A novel, fast and simple method was developed to synthesize the undoped and lanthanide-doped yttrium oxide hollow nanospheres (Y 2 O 3 ⋅HNSs) with multicolored downconversion emission under mild conditions by employing poly (acrylic acid sodium salt) microspheres (PAAS MSs) as active templates followed by a subsequent calcination process. The structure, morphology, formation process, and fluorescent properties are well investigated using various techniques. The results show that the samples can be well indexed to the pure cubic phase of Y 2 O 3 . The possible formation mechanism of the PAAS MSs, PAA-Y precursor, and Y 2 O 3 HNSs are proposed and discussed in detail. Upon ultraviolet excitation, the obtained Y 2 O 3 :Ln 3+ (Ln = Eu, Dy, Er, Tm) HNSs exhibit strong red, yellow–green, blue, yellow emission, respectively. Moreover, a novel single-phased and near-UV-pumped white-light-emitting phosphor Y 2 O 3 :Tm 3+ , Dy 3+ was also successfully fabricated through optimizing the molar ratio among Tm 3+ and Dy 3+ in the Y 2 O 3 host. This material may find potential applications in field-emission display devices and white ultraviolet light-emitting diodes (UV LEDs). Furthermore, this synthesis route may be of great significance in the preparation of other hollow spherical materials. [ABSTRACT FROM AUTHOR]

Abstract: The NaLa(MoO4)2:Ce3+,Tb3+ phosphors were synthesized by a high temperature solid-state reaction. Co-doping of Ce3+ enhances the emission intensity of Tb3+ greatly by transferring its excitation energy to Tb3+. Through an efficient energy transfer process, the obtained phosphors exhibit both a indigo emission of Ce3+ and a yellowish green emission of Tb3+ with considerable intensity under near-ultraviolet excitation (339nm). The energy transfer mechanism from Ce3+ to Tb3+ in NaLa(MoO4)2 host was demonstrated to be dipole–quadrupole interaction. The varied emitted color of the phosphors from indigo to yellow-greenish can be achieved by properly tuning the relative ratio of Ce3+ and Tb3+ through the energy transfer from the Ce3+ to Tb3+ ions. These results indicate that the NaLa(MoO4)2:Ce3+,Tb3+ phosphors have potential applications as an UV-convertible phosphor for white light emitting diodes because of its effective excitation in the near ultraviolet range. [Copyright &y& Elsevier]