Abstract This work demonstrates the luminescence of Mn4+ activated cubic spinel Li4Ti5O12 (LTO) powders. One-step solid-state method was used to obtain eleven samples with different quantities of Mn4+. The deep red emission centered at around 696 nm originates from 2Eg → 4A2g spin forbidden electronic transitions from 3 d3 electron configuration of Mn4+ ion. The concentration quenching of emission is also observed in values of excited-state lifetimes, ranging from 212 μs to 143 μs. Such emission in the red spectral region which can be excited by blue light is suitable for the plant growth LEDs. The exchange charge model (ECM) of crystal field was used to calculate the Mn4+ energy levels in the LTO host. The temperature dependence of the Mn4+ emission in LTO was measured in the 10–350 K temperature range. Excited-state lifetime strongly changes with temperature. A very large value of relative sensitivity of 2.6% K−1 is found at 330 K, which facilitates temperature measurements with the temperature resolution of about 0.26 K. A low concentration of Nb5+ co-doping sensitizes the Mn4+ optical center effectively showing a relative increment of emission intensity.

中文翻译：

---

Mn4+ 活化的 Li4Ti5O12 的发光

摘要 这项工作展示了 Mn4+ 活化立方尖晶石 Li4Ti5O12 (LTO) 粉末的发光。一步固态方法用于获得具有不同量的Mn4+ 的11 个样品。以 696 nm 附近为中心的深红色发射源自 Mn4+ 离子的 3 d3 电子构型的 2Eg → 4A2g 自旋禁区电子跃迁。在激发态寿命值中也观察到发射的浓度猝灭，范围从 212 μs 到 143 μs。这种可以被蓝光激发的红色光谱区域的发射适用于植物生长LED。晶体场的交换电荷模型 (ECM) 用于计算 LTO 主体中的 Mn4+ 能级。在 10-350 K 温度范围内测量了 LTO 中 Mn4+ 发射的温度依赖性。激发态寿命随温度发生强烈变化。在 330 K 处发现了 2.6% K-1 的非常大的相对灵敏度值，这有助于温度测量，温度分辨率约为 0.26 K。低浓度的 Nb5+ 共掺杂使 Mn4+ 光学中心敏感，有效地显示出相对增量排放强度。