Preparation of Eu3+ ions activated Ca2La8(SiO4)6O2 oxyapatite nanophosphors through two-step surfactant-free method and their optical and electrical properties

K3Eu5(PO4)6: hydrothermal synthesis, crystal structure and photoluminescence properties

An anhydrous orthophosphate, K₃Eu₅(PO₄)₆ (tripotassium pentaeuropium hexaphosphate), has been prepared by a high-temperature solid-state reaction combined with hydrothermal synthesis, and its crystal structure was determined by single-crystal X-ray diffraction analysis (SC-XRD). The results show that the compound crystallizes in the monoclinic space group C2/c and the structure features a three-dimensional framework of [Eu₅(PO₄)₆]_∞, with the tunnel filled by K⁺ ions. The IR spectrum, UV-Vis spectrum and luminescence properties of polycrystalline samples of K₃Eu₅(PO₄)₆, annealed at temperatures of 650, 700, 750, 800 and 850 °C, were investigated. Although with a full Eu³⁺ concentration (9.96 × 10²¹ ions cm^-3), the self-activated phosphor K₃Eu₅(PO₄)₆ shows s strong luminescence emission intensity with a quantum yield of 37%. Under near-UV light excitation (393 nm), the series of samples shows the characteristic emissions of Eu³⁺ ions in the visible region from 575 to 715 nm. The sample sintered at 800 °C gives the strongest emission and its lifetime sintered at 800 °C (1.88 ms) is also the longest of all.

Luminescent properties of Eu3+-activated Gd2ZnTiO6 double perovskite red-emitting phosphors for white light-emitting diodes and field emission displays

We synthesized a series of double perovskite Eu3+-activated Gd2ZnTiO6 red-emitting phosphors by a solid-state reaction route and analyzed their morphology, crystallinity, luminescent properties, and thermal stability. Under 270 nm of excitation, the prominent emission peak of the phosphors was found to be located in the red region with the central wavelength of 613 nm corresponding to the intra-4f transition of Eu3+ ions from the 5D0 to 7F2 level. The optimum concentration of the activator was determined to be 7 mol%. The studied phosphors also exhibited good thermal stability with the activation energy of 0.233 eV. The white color emitted from the ultraviolet (UV) light-emitting diode device which was coated by commercial blue-/green-emitting phosphors and Gd1.86ZnTiO6:0.14Eu3+ phosphors exhibited a high color rendering index of 82.9. Furthermore, the cathodoluminescence performance of the resultant phosphors was also investigated in detail. These characteristics of Gd2-2x ZnTiO6:2xEu3+ phosphors make them potential candidates for UV-based white light-emitting diodes and field emission displays.

Facile surfactant- and template-free synthesis and luminescence properties of needle-like calcite CaCO3:Eu3+ phosphors

Simulated diagram of the growth process of needle-like CaCO₃:Eu³⁺ particles.