Facile molten salt synthesis, structural, morphological and optical studies of ASiO₃: Eu²⁺, Er³⁺ (A = Ca, Ba, Sr) perovskites

This work reports structural, morphological and optical studies of alkaline earth metasilicates ASiO₃: Eu²⁺, Er³⁺ (A = Ca, Ba, Sr) perovskites synthesized by the facile molten salt synthesis technique. Using the molten chloride salt, NaCl to create an active reaction medium, the phosphors with doping concentration of Eu²⁺ and Er³⁺ ions varying from 0 to 2 at.% were synthesized at sintering temperature of 950 °C. The crystallographic analysis done by PXRD confirms the crystalline nature, homogeneity and phase purity of synthesized perovskites. The FESEM and TEM micrographs show the distinct morphology and uniform grain connectivity of the particles. The FTIR spectroscopy set forth the finger print of the molecular activities of the constituent elements of the synthesized phosphors. The optical studies done by PL spectroscopy show distinct emissions of synthesized phosphors with enhanced quantum yields over a wide spectral region resulting from the hypersensitive transitions ²P_3/2–⁴I_15/2, ⁴G_7/2–⁴I_15/2, ⁴G_11/2–⁴I_15/2, ⁴H_9/2–⁴I_15/2, ²P_3/2–⁴I_11/2 and ⁴F_7/2–⁴I_15/2 of Er³⁺ ions and crystal field splitting influenced 4f–5d transitions of Eu²⁺ ions. These emissions confirm the important characteristic of color tunability of the phosphors. The dipole–dipole interaction between rare earth ions crucially amend the optical behavior of synthesized phosphors giving rise to distinct spectroscopic characteristics and enhanced lumen output of the synthesized ASiO₃:Eu²⁺, Er³⁺(A = Ca, Ba, Sr) perovskites.