Spectral modification is crucial for luminescent materials. A variety of strategies have been proposed in the literature, including the selection of activator ions with characteristic electron configurations, the modification of the local crystal field, and the design of an emissive center pair and energy transfer. Eu²⁺-activated haloapatites are considered as candidates for phosphor converted light emitting devices due to their excellent stabilities, easy preparation, and high efficiency. In this work, single-phased, single-doped (Ba,Sr)₅(PO₄)₃Br:Eu²⁺ is selected and multiple approaches are applied, leading to multicolor tunabilities of the phosphors, including a crystal field strength controlled spectral shift, occupancy selectivity induced spectral saltation, defect-driven color tunability, and irradiation dependent dynamic chromaticity. In the high Eu²⁺ concentration doped Ba_5−mSr_m(PO₄)₃Br phosphor, the main emission band shifts from 448 to 452 nm with increasing Sr²⁺/Ba²⁺ ratio, and a second emission band around the green region uplifts in the binary metal solid solution phosphors, leading to variable emission colors from blue to cyan under near UV excitation. Moreover, oxygen vacancy (V_O) defects formed under synthetic reducing conditions endow the bromoapatites with bright self-activated luminescence. In the low Eu²⁺ concentration doped Ba₂Sr₃(PO₄)₃Br, the combination of the broad yellow-green emission from V_O and bluish emission from Eu²⁺ contributes to a full spectrum feature. The gradual increase of Eu²⁺ concentrations regulates the tunable emission from yellow-green, through white, to blue under short UV excitation. Furthermore, due to the different absorption preferences of these two centers, Ba₂Sr₃(PO₄)₃Br:0.01Eu²⁺ shows white light emission under 254 nm irradiation while blue emission when exposed to 365 nm irradiation. The materials with multicolor luminescence show promising versatile applications in lighting, biological detection and anti-counterfeiting. The cooperative effects of multiple strategies provide a promising approach to regulate the optical properties of inorganic phosphors.

中文翻译：

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单一Eu2 +掺杂（Ba，Sr）5（PO4）3Br荧光粉的多光谱可调性

光谱修改对于发光材料至关重要。文献中已经提出了多种策略，包括选择具有特征电子构型的活化剂离子，改变局部晶体场以及设计发射中心对和能量转移。Eu ²⁺活化的卤磷灰石由于其优异的稳定性，易于制备和高效率而被认为是磷光体转换的发光器件的候选物。在这项工作中，单相，单掺杂（Ba，Sr）₅（PO ₄）₃ Br：Eu ²⁺选择并应用多种方法，导致磷光体的多色可调性，包括晶场强度控制的光谱偏移，占用选择性引起的光谱盐化，缺陷驱动的色可调性以及与辐照有关的动态色度。在掺杂高Eu ²⁺浓度的Ba _{5− m} Sr _m（PO ₄）₃ Br荧光粉中，随着Sr ²⁺ / Ba ^2+的增加，主发射带从448 nm移至452 nm。二元金属固溶体荧光粉中绿色区域周围的第二发射带上升，导致在近紫外光激发下从蓝色到青色的可变发射颜色。此外，氧空位（V _ö）合成的还原条件下形成的缺陷赋予明亮的自激活发光的bromoapatites。在低Eu ²⁺浓度掺杂的Ba ₂ Sr ₃（PO ₄）₃ Br中，来自V _O的宽黄绿色发射和来自Eu ^2+的蓝光发射共同构成了全光谱特征。Eu ²⁺逐渐增加短时紫外线激发下，浓度可调节从黄绿色到白色的可调发射到蓝色。此外，由于这两个中心的吸收偏好不同，Ba ₂ Sr ₃（PO ₄）₃ Br：0.01Eu ²⁺在254 nm照射下显示白色发光，而在365 nm照射下显示蓝色发光。具有多色发光的材料在照明，生物检测和防伪中显示出广阔的应用前景。多种策略的协同作用提供了一种有前途的方法来调节无机磷光体的光学性能。