Robust luminescent material with superior color purity: Sm3+ ion-doped CaAl4O7 phosphor synthesized in a cost-effective approach for solid-state lighting applications

Abstract

This work reports the synthesis of Sm3+ ion doped calcium dialuminate phosphor by microwave-assisted combustion synthesis technique. Phase purity and the crystal structure of the phosphors were affirmed by PXRD analysis and was found to have monoclinic structure. SEM study was performed to analyze the surface morphology. FTIR study clarifies the existence of functional groups. The optical bandgap of 4.43 eV was determined for CaAl4O7:Sm3+ (x = 0.03) sample. The emission spectra of the sample recorded upon excitation at 403 nm suggest orange color emission around 601 nm pertaining to the transition 4G5/2→6H7/2 of Sm3+ ions. The optimal dopant concentration was established at 3 mol%. CIE chromaticity coordinates of (x = 0.6029, y = 0.3964) were established for the optimized sample. Correlated color temperature of 1620 K demonstrates the emission of light in warmer region. The superior color purity of 99.21 % and color rendering index of 77 for the optimized phosphor material was manifested. The photoluminescence (PL) decay time (for Sm3+ concentration = 0.03 mol) was found to be 0.73 ms. Thermal stability of the sample was investigated and the activation energy was determined to be 0.152 eV by temperature-dependent PL study. To explore the lighting ability of the phosphor, phosphor-in-glass (P-i-G) material was fabricated. CaAl4O7:Sm3+ (x = 0.03) based P-i-G material validates excellent luminous efficacy (360 lm/W) and luminous efficiency (52.70 %) which affirms its practical applications.