Effect of Li, Na, K cations on photoluminescence of GdAlO3:Eu3+ nanophosphor and study of Li cation on its antimicrobial activity

Highlights: • Red-emitting monovalent doped GdAlO₃:Eu³⁺NPs were synthesized via combustion route. • Judd–Ofelt intensity parameters, radiative properties were determined from PL data. • GdAlO₃:Eu³⁺,Li⁺ nanophosphor is a potential red component in white LEDs. • Antimicrobial activities were carried out against pathogenic microorganisms. • Nanoparticles show potential applications in white LED, medicine and agriculture. Alkali metal cations such as Li, Na, K (1mol %) co-doped GdAlO₃:Eu³⁺ (1 mol%) nanophosphors were synthesized by solution combustion technique using oxalyldihydrazide (ODH: C₂H₆N₄O₂) as fuel. The structural, morphological, luminescence and antimicrobial activity has been employed to the synthesized nanoparticles. All compounds crystallized in the pure orthorhombic phase with no impurity peak. SEM micrographs showed the agglomerated and irregular shaped particles. The average crystallite size was calculated by William-Hall plots and is found to be in the range 30–40 nm. The characteristic emission peaks of Eu³⁺ ions were recorded and it is due to ⁵D₀→⁷F_J (J = 1, 2, 3, 4) transitions. The PL intensity of GdAlO₃:Eu³⁺nano phosphor was improved evidently by alkali metal cation co-doping, due to local distortion of crystal field surrounding the Eu³⁺ activator. These nanophosphors find potential applications in WLEDs and solid state lighting. Antimicrobial activity of GdAlO₃:Eu³⁺: Li⁺ nanophosphor against pathogenic microorganisms of both human and plants was carried out by using micro plate dilution technique for bacteria and food poison method for fungi.