Optical and structural investigations of MLaAlO₄:Eu³⁺ (M = Mg^2 +, Ca²⁺, Sr²⁺, and Ba²⁺) nanophosphors for full-color displays

Abstract

A series of Eu³⁺ -doped MLaAlO₄ (M = Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺) was synthesized via self-sustained solution combustion method. The samples were prepared at 600 °C, using large range of Eu³⁺ ion concentration (0.01–0.05 mol) to investigate the effect of concentration of dopant on the luminescence. The optimal dopant ion concentration obtained was 0.03 mol for the prepared aluminate lattice. Upon excitation at 393 nm, the samples showed the dominant photoluminescence emission bands in red region of the spectrum. The red emission of Eu³⁺ -activated phosphors corresponds to ⁵D₀ → ⁷F₂ (forced electric dipole) transition positioned at 606–611 nm. The samples were also calcined to a higher temperature to analyze the influence of temperature on the luminous efficacy. The structural determination was done via the combined efforts of Powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM) analysis. PXRD patterns of samples contain sharp peaks in 10°–80° region. Diffraction Pattern of CaLaAlO₄ material has been found in close agreement to JCPDS card no. 85-1071 confirming the tetragonal crystal structure with 14/mmm space group. The crystalline nature of materials increases with rise in temperature. TEM micrographs exhibited the spherical shape of particles in 13–30 nm size. FT-IR spectra of materials showed peaks in 400–1000 cm⁻¹ corresponding to lanthanum–oxygen and aluminum–oxygen bond vibrations. Due to excellent photoluminescent and suitable CIE coordinates, the Eu³⁺ -doped MLaAlO₄ could have brilliant applications in the development of effective red phosphor for modern display devices and white light-emitting diodes.