High-crystalline, hollow-mesh-like Tm3+/Yb3+-co-doped La2Ti2O7 (LTO) submicron fibers are prepared by electrospinning technique and identified as monoclinic structure. The LTO matrix fibers and the Tm3+/Yb3+-co-doped fibers exhibit different frequency upconversion luminescence. The fluorescence of the matrix at the 487 and 542 nm is ascribed to the two-photon absorption and the cross-relaxation processes caused by the defect center at 977 nm excitation, respectively. The upconversion luminescence intensity enhances when the rare-earth ions are incorporated into LTO fibers. The emissions of Tm3+ in co-doped LTO membranes at 479 and 789 nm under the excitation of 977 nm indicate the effectiveness of the three- and two-photon absorption processes, respectively. The pristine LTO fibers have the potential to be employed for water purification as a laser-excited photocatalytic material because the LTO materials are conducive to absorbing the highly penetrating NIR laser. Furthermore, the Tm3+/Yb3+ ions play a positive role in further promoting the laser-absorption capacity, and the hybrid excitation mechanism in the Tm3+/Yb3+-co-doped LTO composite fibers provides a new perspective for the development of anti-laser inorganic materials.

中文翻译：

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空心La2Ti2O7上转换荧光的混合激发机制：Tm3+/Yb3+亚微米纤维

采用静电纺丝技术制备了高结晶、空心网状 Tm3+/Yb3+-共掺杂 La2Ti2O7 (LTO) 亚微米纤维，经鉴定为单斜结构。LTO基体光纤和Tm3+/Yb3+-共掺杂光纤表现出不同的频率上转换发光。基质在 487 和 542 nm 处的荧光分别归因于双光子吸收和由缺陷中心在 977 nm 激发处引起的交叉弛豫过程。当稀土离子掺入 LTO 纤维时，上转换发光强度增强。在 977 nm 激发下，共掺杂 LTO 膜中 Tm3+ 在 479 和 789 nm 处的发射分别表明了三光子吸收过程和两光子吸收过程的有效性。原始的 LTO 纤维有可能作为激光激发的光催化材料用于水净化，因为 LTO 材料有助于吸收高穿透性的 NIR 激光。此外，Tm3+/Yb3+离子对进一步提高激光吸收能力起到积极作用，Tm3+/Yb3+-共掺杂LTO复合纤维中的混合激发机制为抗激光无机材料的发展提供了新的视角.