Sahu Manjulata, Phatak Nimai, Saxena M K
Radioanalytical Chemistry Division, Bhabha Atomic Research Centre Mumbai 400 085 India.
Radiochemistry Division, Bhabha Atomic Research Centre Mumbai 400 085 India
RSC Adv. 2021 May 12;11(28):17488-17497. doi: 10.1039/d1ra01715b. eCollection 2021 May 6.
The glass-ceramic form of phosphor materials can overcome the many serious issues of phosphor/silicone composite in commercial phosphor-converted LEDs and are considered as new-generation color converters. In this report, we have shown a novel approach of developing inorganic red phosphor [Eu:La(MoO)] in the glass-ceramic form based on lanthanum molybdate system. The ceramic form of the compound was found to have a glass transition temperature of 1002 °C, as confirmed by TGA and DSC studies. Further, XRD, FTIR and Raman studies also confirmed that the compounds prepared at 1050 °C are in glass-ceramic form, while those prepared at 750 °C are in ceramic form. Photoluminescence studies showed that both the ceramic and glass-ceramic forms of the phosphor are red color-emitting materials. However, the glass-ceramic forms have better color purity and more radiation transition probabilities. Further, the decay kinetics of both ceramic and glass-ceramic forms confirmed that only those Eu ions which exist in the grain boundaries of the ceramics go inside the glass network structure upon heating the compound at or above the glass transition temperature. On the other hand, Eu ions which exist at the La-site in the bulk of the particles are retained in the ceramic form in the glass-ceramic mixture.
磷光体材料的玻璃陶瓷形式可以克服商用磷光体转换发光二极管中磷光体/硅酮复合材料的许多严重问题，被视为新一代颜色转换器。在本报告中，我们展示了一种基于钼酸镧体系开发玻璃陶瓷形式的无机红色磷光体[Eu:La(MoO)]的新方法。通过热重分析（TGA）和差示扫描量热法（DSC）研究证实，该化合物的陶瓷形式的玻璃化转变温度为1002℃。此外，X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和拉曼研究也证实，在1050℃制备的化合物为玻璃陶瓷形式，而在750℃制备的化合物为陶瓷形式。光致发光研究表明，磷光体的陶瓷形式和玻璃陶瓷形式都是发红光的材料。然而，玻璃陶瓷形式具有更好的色纯度和更多的辐射跃迁概率。此外，陶瓷形式和玻璃陶瓷形式的衰减动力学证实，只有那些存在于陶瓷晶界中的Eu离子在将化合物加热到玻璃化转变温度或以上时会进入玻璃网络结构。另一方面，存在于颗粒主体中La位点的Eu离子在玻璃陶瓷混合物中以陶瓷形式保留。
