Cation substitution induced structural phase transitions and luminescence properties of Eu3+-doped A2LaNbO6 (A = Ba, Sr, and Ca) double perovskite

Recently, double perovskites oxides have emerged as a prominence in the luminescence research, attributed to their adaptable structure, diverse chemical compositions, and stability. In this work, we investigated intricate relationship between cation substitution-induced structural modifications and the luminescent properties of Eu3+ doped A2LaNbO6, where A represents Ba, Sr, and Ca. The structural transitions in the Eu3+-doped A2LaNbO6 system were identified through comprehensive structural analysis techniques, including X-ray diffraction and Rietveld refinement. Under both photo- and cathode-excitations, the emission properties of Eu3+ exhibited marked enhancements as the structural deformations increased. Particularly intriguing were the anomalies in emission intensities and distribution of emission spectra occurring near the structural transition. Furthermore, we explored the Eu3+ doping dependence of the structural and emission properties in Ca2LaNbO6. Notably, the photoluminescence quantum yield reached a fairly high value of 83% under 465 nm photoexcitation at the Eu3+ concentration of 0.5. Additionally, we demonstrated that integration of Eu3+-doped Ca2LaNbO6 into phosphor-based white light emitting diodes (WLEDs) lead to improvements in the correlated color temperature of WLEDs.