Eu掺杂KNN陶瓷的制备及可调性发光研究

稀土离子掺杂铁电陶瓷是一类新型光致变色材料, 在光开关、光信息存储等领域具有潜在应用价值。本研究采用水热法制备了(K_0.5 Na_0.5)_1-xEu_xNbO₃(KNN:xEu)前驱体粉体, 随后利用高温烧结得到对应陶瓷样品。在465 nm激发下, 观察到615 nm处有强的红色发光, 对应于Eu ³⁺的 ⁵D₀→ ⁷F₂跃迁。通过紫外光照射, KNN:Eu陶瓷从乳白色变为深灰色。随后经过200 ℃加热10 min, 着色陶瓷又变回到初始颜色, 显示出良好的光致变色行为。紫外照射和反复加热循环可以有效调控该陶瓷的发光强度。且经过多次循环之后, 发光强度没有明显衰减。在紫外光照射下, KNN:0.06Eu陶瓷发光强度的可调比(ΔR_t)高达83.9%, 说明发光具有良好的可调性。进而结合发光中心和色心之间的能量转移, 对KNN:Eu陶瓷的光致变色和发光机理进行了解释。

Preparation and Tunable Luminescence of Eu Doped KNN Ceramics

Rare-earth doped inorganic ferroelectrics are considered as novel photochromic materials, with potential applications for optical switch and information storage (K_0.5Na_0.5)_1-xEu_xNbO₃ (KNN:xEu) ceramics were prepared by high temperature calcination, with precursor powder obtained by hydrothermal method. Strong red emission at 615 nm was observed which corresponds to the ⁵D₀→ ⁷F₂ transition of Eu ³⁺ under excitation of 465 nm. Under UV light irradiation for 3 min, the color of the ceramics turned from milky white to dark gray. The colored samples returned to the original color when heated at 200 ℃ for 10 min, showing strong photochromic behavior. Meanwhile, the luminescence intensity of Eu ³⁺ can be tuned without obvious degradation by alternating UV light and heat stimulus. Upon UV light irradiation, large luminescence modulation ratio (ΔR_t) up to 83.9% was achieved for KNN:0.06Eu, indicating good luminescence switching behavior. A possible mechanism for non-radiative energy transfer from the luminescent center to the color center was proposed according to their luminescent behavior.