Surface coatings have been widely used to improve phosphor characteristics for the purpose of increasing luminescence intensity and protecting against degradation. In this study, an uncoated La₂O₂S:Eu³⁺ thin film is compared to films coated by graphene oxide, as prepared or annealed in an inert or reducing atmosphere. The characteristic red emission of Eu³⁺ ions was observed for all samples and attributed to ⁵D₀-⁷F₂ transitions, while no luminescence associated with graphene oxide was observed. The luminescence intensity from the as-coated sample and the one annealed in an inert Ar atmosphere was less, compared to the uncoated film, whereas the coated sample annealed in a reducing atmosphere (Ar/H₂) had emission, which was of similar intensity to the uncoated sample. Its degradation, and that of the uncoated sample, were studied by recording Auger electron spectroscopy and cathodoluminescence measurements, simultaneously. During electron irradiation, the surface of the uncoated sample was converted to a much more luminescent layer as C and S were gradually removed from the surface. Auger electron spectroscopy measurements of the coated sample showed that even initially, it had almost no S on the surface. The loss of S was attributed to annealing in Ar/H₂, where H₂S gas may be produced as the phosphor was converted into La₂O₃. This La₂O₃ subsequently formed La(OH)₃ due to its hydroscopic nature. Unlike the uncoated sample, from which C due to unintentional contamination was fairly easily removed from the surface, C on the surface of the coated sample became less but was resistant to removal, which was associated with the formation of CHLaO₃ at the surface as suggested by x-ray diffraction. Although coating with graphene oxide did not result in chemically stable La₂O₂S:Eu³⁺ thin films, the cathodoluminescence intensity of both the uncoated and graphene oxide coated samples annealed in reducing atmosphere increased during electron beam exposure (with no change in the form of the emission spectra) so that such films may have potential cathodoluminescence applications.

中文翻译：

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脉冲激光沉积 La2O2S:Eu3+ 薄膜的表征和氧化石墨烯层涂层的影响

表面涂层已被广泛用于改善磷光体特性，以达到增加发光强度和防止退化的目的。在这项研究中，将未涂层的 La ₂ O ₂ S:Eu ³⁺薄膜与在惰性或还原气氛中制备或退火的氧化石墨烯涂层薄膜进行比较。所有样品均观察到Eu ³⁺离子的特征性红色发射，归因于⁵ D ₀ - ⁷ F ₂转变，而没有观察到与氧化石墨烯相关的发光。与未涂层薄膜相比，涂层样品和在惰性 Ar 气氛中退火的样品的发光强度较低，而涂层样品在还原气氛中退火 (Ar/H ₂) 有发射，其强度与未涂层样品相似。通过同时记录俄歇电子能谱和阴极发光测量来研究其降解和未涂层样品的降解。在电子辐射期间，随着 C 和 S 逐渐从表面移除，未涂层样品的表面转化为更加发光的层。涂层样品的俄歇电子能谱测量表明，即使在最初，它的表面也几乎没有硫。S 的损失归因于在 Ar/H ₂中退火，其中当磷光体转化为 La ₂ O _{3时可能产生 H 2} S 气体。La ₂ O ₃随后形成 La(OH)₃由于其吸湿性。与未涂层样品不同，由于无意污染，C 很容易从表面去除，涂层样品表面的 C 变少但难以去除，这与所建议的表面 CHLaO 3 的形成_有关通过 X 射线衍射。尽管涂有氧化石墨烯不会产生化学稳定的 La ₂ O ₂ S:Eu ³⁺薄膜，但在电子束曝光期间，在还原气氛中退火的未涂敷和氧化石墨烯涂敷样品的阴极发光强度增加（没有变化发射光谱的形式），因此此类薄膜可能具有潜在的阴极发光应用。