BaLu_2−xF₈:xLn³⁺ crystals have been synthesized via a one-step hydrothermal route without any surfactants. X-ray diffraction (XRD), scanning electron microscopy (SEM), and down-shift/up-conversion photoluminescence spectroscopy were used to characterize the samples. Pure monoclinic BaLu₂F₈ crystals were obtained at pH = 7 with NaBF₄ as a fluoride source. Doping 0.06 mmol Ln³⁺ ions from Ho³⁺ to La³⁺ and doping Yb³⁺ ions from 0.1 to 0.4 mmol both have caused dramatic changes to the product's morphology from prismatic microrods of about 10 μm to particles of about 3 μm aggregated by flakes. The differences in the phase, size and shape of the final products were greatly related to the fluoride source and pH values, which have been studied in detail. In addition, surfactants also affected the phase and morphology of the BaLu₂F₈ crystals. Multicolor down-shift emission was achieved in the BaLu_1.94F₈:0.06Ln³⁺ (Ln = Sm, Eu, Tb, Dy, Er and Tm) crystals under UV lamp excitation at 365 nm, and multicolor UC luminescence has been achieved in BaLu₂F₈:Yb³⁺,Ln³⁺ (Ln = Er, Tm, Ho) systems. When the Yb³⁺–Er³⁺ ions are co-doped into the host, the mechanism for the red emission (⁴F_9/2 → ⁴I_15/2) retains the tri-photon process like the single-doped Er³⁺ ion, but the mechanism for the green emission (²H_11/2/⁴S_3/2 → ⁴I_15/2) is a two-photon process. Furthermore, the UC luminescence mechanism for the co-doped Yb³⁺–Ho³⁺ pairs is also a tri-photon process in the BaLu₂F₈ matrix. The as-prepared BaLu₂F₈:Ln³⁺ phosphors have potential applications in the fields of light emitting devices, three-dimensional displays and backlights.

中文翻译：

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BaLu2F8：Ln3 +晶体的水热合成：相/形貌演化，能量转移和可调多色发光

BaLu _{2- x} F ₈：x Ln ³⁺晶体是通过一步水热法合成的，没有任何表面活性剂。X射线衍射（XRD），扫描电子显微镜（SEM）和下移/上转换光致发光光谱法用于表征样品。以NaBF ₄为氟化物源，在pH = 7时获得纯单斜BaLu ₂ F ₈晶体。从Ho ³⁺向La ³⁺掺杂0.06 mmol Ln ³⁺离子并掺杂Yb ³⁺从0.1到0.4 mmol的离子都会引起产品形态的急剧变化，从大约10μm的棱柱形微棒到薄片状聚集的大约3μm的颗粒。最终产品的相，大小和形状的差异与氟化物来源和pH值有很大关系，对此已进行了详细研究。另外，表面活性剂还影响BaLu ₂ F ₈晶体的相和形态。在365 nm的UV灯激发下，BaLu _1.94 F ₈：0.06Ln ³⁺（Ln = Sm，Eu，Tb，Dy，Er和Tm）晶体实现了多色下移发射，并且在1989年实现了多色UC发光。巴鲁₂ F ₈：Yb ³⁺，Ln ³⁺（Ln = Er，Tm，Ho）系统。当镱³⁺ -Er ³⁺离子共掺杂到宿主，该机构用于红色发光（⁴ ˚F _9/2 → ⁴我_15/2）保持一样的单掺杂的铒三光子过程^{3 +}离子，但绿色发射的机理（² H _11/2 / ⁴ S ₃ / ₂ → ⁴ I _15/2）是一个双光子过程。此外，BaLu ₂中共掺杂的Yb ³⁺ -Ho ³⁺对的UC发光机理也是三光子过程。F ₈矩阵。所制备的BaLu ₂ F ₈：Ln ³⁺磷光体在发光器件，三维显示器和背光源领域具有潜在的应用。