Mn⁴⁺ ion-doped red-emitting oxides are promising candidates for light-emitting-diode phosphors, but the formation and stabilization of Mn⁴⁺ in the oxide matrix remain a challenge due to the spontaneous reduction of Mn⁴⁺ to Mn²⁺. In this work, we demonstrate that the incorporation of Li⁺ can regulate the valence of Mn ions doped in spinel-phase ZnAl₂O₄ and enable tuning of the luminescence of Mn²⁺ and Mn⁴⁺ dopants. Both experimental and calculation results show that the incorporation of Li⁺ ions can lead to localized charge accumulation around themselves, thereby consuming the excess charges and suppressing the self-reduction of Mn⁴⁺. This finding allows for the realization of pure red emission of Mn⁴⁺ in ZnAl₂O₄ for the first time and the fabrication of a corresponding warm white-light-emitting-diode prototype. The Li⁺-dependent dual emission of Mn²⁺ (green) and Mn⁴⁺ (red) co-doped in ZnAl₂O₄ can be conveniently utilized to design a ratiometric optical thermometer with excellent visual responses. This work not only offers new atomistic insights into regulating the valence state of Mn ions but also provides an effective method for improving the performance of Mn⁴⁺-activated light-emitting-diode phosphors and devising a good phosphorescent probe for fluorescence-intensity-ratio temperature sensing.

中文翻译：

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Li ⁺结合驱动的局部电荷积累，可实现具有可调光致发光的高效LED荧光粉

Mn ⁴⁺离子掺杂的红色发光氧化物是发光二极管磷光体的有希望的候选物，但是由于Mn ⁴⁺自发还原为Mn ²⁺，在氧化物基体中Mn ⁴⁺的形成和稳定仍然是一个挑战。。在这项工作中，我们证明Li ⁺的掺入可以调节尖晶石相ZnAl ₂ O _4中掺杂的Mn离子的化合价，并能够调节Mn ²⁺和Mn ⁴⁺掺杂剂的发光。实验和计算结果均表明，Li ⁺的结合离子会导致自身附近的局部电荷积累，从而消耗过量的电荷并抑制Mn ⁴⁺的自还原。这一发现首次实现了ZnAl ₂ O ₄中Mn ⁴⁺的纯红色发射，并制造了相应的暖白色发光二极管原型。ZnAl ₂ O ₄共掺杂的Mn ²⁺（绿色）和Mn ⁴⁺（红色）的Li ⁺依赖性双发射可以方便地用于设计具有出色视觉响应的比例式光学温度计。这项工作不仅为调节Mn离子的价态提供了新的原子学见解，而且为提高Mn ⁴⁺激活的发光二极管磷光体的性能和设计出良好的荧光强度比的磷光探针提供了有效的方法。温度感应。