Near-infrared (NIR) phosphor conversion light-emitting diodes (pc-LEDs) have great application potential as NIR light sources in many fields such as food analysis, night vision illumination, and bioimaging for noninvasive medical diagnosis. In general, phosphors synthesized by a high-temperature solid-phase method have large particle sizes and have to be processed to fine powders by a grinding process, which may introduce surface defects and lower the luminous efficiency. Here, we report a sol–gel sintering method with ammonium nitrate and citric acid as the sacrificing agents to synthesize high purity, nanosized (less than 50 nm) Zr⁴⁺/Ni²⁺ codoped MgAl₂O₄ spinel NIR phosphors, in which MgAl₂O₄ spinel is the matrix, Ni²⁺ is the luminous center, and Zr⁴⁺ acts as the charge compensator. We systematically characterized the crystal structures and NIR luminescence properties of the Ni²⁺-doped MgAl₂O₄ and the Zr⁴⁺/Ni²⁺ codoped MgAl₂O₄. Under 390 nm light excitation, the emission spectrum of the Ni²⁺-doped MgAl₂O₄ phosphor covers 900–1600 nm, the half-peak width is 251 nm, and the peak position is located at 1230 nm. We demonstrated that by incorporating small amounts of Zr⁴⁺ as the charge compensator, the NIR emission intensity of the Zr⁴⁺/Ni²⁺ codoped MgAl₂O₄ nanosized phosphor was doubled over that of the Ni²⁺-doped MgAl₂O₄ phosphor. The optimal content of the charge compensator was 2 mol %. More importantly, the inclusion of Zr⁴⁺ led to a NIR phosphor with improved thermal stability in luminous properties, and the luminous intensity measured at 100 °C was 33.83% of that measured at room temperature (20 °C). This study demonstrates that NIR phosphor nanomaterials with high-purity and enhanced optical properties can be designed and synthesized through the charge compensation strategy by a sol–gel sintering method.

中文翻译：

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溶胶-凝胶燃烧法合成高性能 Ni2+ 激活 MgAl2O4 尖晶石近红外荧光粉的电荷补偿策略

近红外（NIR）磷光转换发光二极管（pc-LED）作为近红外光源在食品分析、夜视照明和无创医学诊断生物成像等许多领域具有巨大的应用潜力。一般而言，高温固相法合成的荧光粉粒径较大，必须通过研磨工艺加工成细粉，这可能会引入表面缺陷并降低发光效率。在此，我们报道了一种以硝酸铵和柠檬酸为牺牲剂的溶胶-凝胶烧结法合成高纯度、纳米尺寸（小于50 nm）Zr ⁴⁺ /Ni ²⁺共掺杂MgAl ₂ O ₄尖晶石近红外荧光粉，其中MgAl ₂ O ₄尖晶石为基体，Ni ²⁺为发光中心，Zr ⁴⁺为电荷补偿体。我们系统地表征了Ni ²⁺掺杂的MgAl ₂ O ₄和Zr ⁴⁺ /Ni ²⁺共掺杂的MgAl ₂ O ₄的晶体结构和近红外发光性质。在390 nm光激发下，Ni ²⁺掺杂MgAl ₂ O ₄荧光粉的发射光谱覆盖900～1600 nm，半峰宽为251 nm，峰位置位于1230 nm。我们证明，通过加入少量的Zr ⁴⁺作为电荷补偿剂，Zr ⁴⁺ /Ni ²⁺共掺杂MgAl ₂ O _{4纳米尺寸磷光体的近红外发射强度比Ni} ²⁺掺杂MgAl ₂ O的近红外发射强度增加了一倍。₄荧光粉。电荷补偿剂的最佳含量为2mol%。更重要的是，Zr ⁴⁺的加入使得近红外荧光粉的发光性能的热稳定性得到改善，在100℃下测量的发光强度是在室温（20℃）下测量的33.83%。这项研究表明，可以通过溶胶-凝胶烧结方法的电荷补偿策略设计和合成具有高纯度和增强光学性能的近红外荧光粉纳米材料。