Research On The Synthesis And Luminescent Properties Of Eu-Activated Tricolor Long-Lasting Phosphors

Long-lasting phosphors?LLPs? have attracted much attention for widely applications like lighting, transportation, medical treatment and decorations, because of its energy storing property and eco-friendly advantage. In order to meet the need of applications, it is crucial to solve the problem that how to realize full color emitting of LLPs. Currently, Eu-activated blue and green LLPs are already applicable except for requiring some improvements, while red phosphors have poor performance and need in-depth exploration and research.In this paper, we synthesized a series of green SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors, blue Ca Al2O4:Eu²⁺, Nd³⁺ phosphors and red Ca₂SnO₄:Eu³⁺ phosphors by high-temperature solid state reaction, respectively. The photoluminescence properties and afterglow performance of tricolor LLPs were systematically investigated. Besides, the luminescent properties of materials changed through ?-ray irradiation and different sintering atmosphere. The main work summarized as the following:?1? The luminescent properties of SrAl₂O₄:Eu²⁺, Dy³⁺ and impact of ?-ray irradiation on its properties were systematically investigated.The results revealed that SrAl₂O₄:Eu²⁺, Dy³⁺ can be excited by UV light at the wavelength from 280 nm to 450 nm. T he emission spectra exhibited a broad band with the peak position near 520 nm. It contributes to 4f65d1?4f7 transition of Eu²⁺, and Dy³⁺ acts as the assistant activator. After ?-ray radiation, the photoluminescent intensity of the sample slightly decreased, but the afterglow intensity was enhanced in a certain extent.?2? The luminescent properties of CaAl₂O₄:Eu²⁺, Nd³⁺ and impact of ?-ray irradiation on its properties were systematically investigated. The results indicated that CaAl₂O₄:Eu²⁺, Nd³⁺ can be efficiently excited by UV light in the region of 275-400 nm. The emission spectra exhibited a broad band peaking at 520 nm due to the transition between the 4f7 and 4f65 d levels. Nd³⁺ plays a role of the assistant activator. After ?-ray radiation, the photoluminescent intensity of the sample decreased, but the afterglow performance was improved as a result of the increase of oxygen vacancies.?3? The influences of concentration of Eu³⁺, ?-ray irradiation and different sintering atmosphere in the luminescent properties of Ca₂SnO₄:Eu³⁺ were systematically investigated, respectively. The results showed that Ca₂SnO₄:Eu³⁺ exhibited characteristic sharp lines originating from the 5D1 and ⁵D₀ to 7FJ transitions of Eu³⁺ under the excitation of UV light at 250-350 nm. The luminescence quenching of Eu³⁺ was observed and the quenching concentration was 1%. After ?-ray radiation, the Eu³⁺ site approached the center of inversion, which resulted in the increase of ⁵D₀?7F1 emission and the decrease of ⁵D₀?⁷F₂ emssion. Comparing to the properties of phosphor prepared in air atmosphere, the phosphor prepared in nitrogen condition had less oxygen vacancies, which led to the enhancement of luminescent property and the decline of afterglow property. However, both the photoluminescent and afterglow properties of the phosphor prepared in vacuum atmosphere were improved because of the energy transfer between VO and Eu³⁺ and the increase of the number of oxygen vacancies.