Abstract Undoped and Ce-doped hexagonal BiPO4 were synthesized by a precipitation method and characterized on their structure, Ce spatial distribution and chemical state, together with detailed luminescence spectroscopy investigation through systematic variation of the excitation wavelength (λexc) over the broad range 250-460 nm combined with radioluminescence measurements and extensive literature review. Up to five distinct emission bands were observed, depending on λexc and on the presence or not of the activator. The host presented three emission bands: the 350 nm (3.54 eV) band was ascribed to a defect, the 405 nm (3.06 eV) band was ascribed to metal-to-metal charge transfer (MMCT), and the 570 nm (2.18 eV) band was ascribed to the Bi3+ 3P1 → 1S0 transition. The presence of Bi3+ ions perturbed by oxygen vacancies in the coordination polyhedron at varying distances to the Bi3+ ions created states with lower energies than the states of unperturbed Bi3+. Ce-incorporation led to the creation of two partially superimposing bands at about 445 nm (2.79 eV) and 490 nm (2.53 eV). Strong interaction between Ce3+ and the host was observed. These results led to enhanced understanding of the intrinsic and extrinsic luminescence of this material that presents considerable controversy in the literature.

中文翻译：

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未掺杂和掺杂 Ce 的六方 BiPO4 的发光

摘要 通过沉淀法合成了未掺杂和掺杂 Ce 的六方 BiPO4，并对其结构、Ce 空间分布和化学状态进行了表征，并通过激发波长 (λexc) 在 250-460 范围内的系统变化进行了详细的发光光谱研究。 nm 结合辐射发光测量和广泛的文献综述。观察到多达五个不同的发射带，这取决于 λexc 和激活剂的存在与否。主机呈现三个发射带：350 nm (3.54 eV) 带归因于缺陷，405 nm (3.06 eV) 带归因于金属到金属电荷转移 (MMCT)，以及 570 nm (2.18 eV) ) 带归因于 Bi3+ 3P1 → 1S0 转变。Bi3+ 离子的存在被配位多面体中与 Bi3+ 离子不同距离处的氧空位扰动，产生的态能量低于未受扰动的 Bi3+ 态。Ce 掺入导致在大约 445 nm (2.79 eV) 和 490 nm (2.53 eV) 处产生两个部分重叠的带。观察到 Ce3+ 与宿主之间的强相互作用。这些结果增强了对这种材料的内在和外在发光的理解，这在文献中引起了相当大的争议。