Abstract:
A new series of narrow orange emitting phosphors in 1:2 B-site cation ordered Eu3+ doped triple Perovskite Ba3CaNb2O9 was prepared by the conventional solid-state route. Powder X-ray diffraction analysis of these phosphors confirms the formation of trigonal perovskite-type structure with the space group P-3m1 and Z = 3. The weak intensity superlattice reflections at low 2θ angles support the idea of 1:2 ordering on the B-site. UV–visible absorption spectra show strong absorption below 325 nm. These phosphors exhibit dominant narrow orange emission with fwhm ~ 4 nm due to allowed magnetic dipole transition, 5D0–7F1 under near-UV (394 nm), or charge transfer band (288 nm) excitations. The intensity for the CT band excitation (x = 0.2) is double that of the direct Eu3+ excitation at 394 nm inferring good host sensitization by way of energy transfer to Eu3+ ions. The ordering on the B-site cations aids a high concentration quenching in the Ba3CaNb2O9:Eu3+ phosphor at 20 mol%. The low asymmetric ratio values and high lifetimes corroborate the environment of Eu3+ ions in most symmetrical surrounding of the host. The CIE color co-ordinates of Ba3CaNb2O9:0.2Eu3+ phosphor are (0.57, 0.41) that are close to the Nichia Corporation developed Amber LED NSPAR70BS. The above results demonstrate that the Ba3CaNb2O9:0.2Eu3+ phosphor is a potential candidate for near-ultraviolet-based phosphor-converted white light-emitting diodes.
