Structural elucidation, electron density mapping and optical investigation of rare-earth Dy³⁺ ion doped LiAl₅O₈ phosphor for its bright luminescence

In this article, LiAl₅O₈:Dy³⁺ phosphor was examined for structural and optical properties. The samples were synthesized via solution combustion synthesis (SCS) under fixed temperature. The phase formation of the compound was confirmed by X-ray diffraction data by doing Retrieved refinement using Full prof software. The spinel matrix belongs to a space group of P4332, hence reveals spinel structure. By doing Gauss fitting of many XRD peak, average particle distribution was found to be 10 μm. The sedimentation and segregation of particle distribution embedded over larger mass recorded form SEM analysis and X-ray diffraction shows close approximation (2 μm to 20 μm) which enhances its luminescence. The crystal geometry of LiAl₅O₈ spinel matrix was obtained from Vesta Software. Electron density mapping of compound calculated by G-Fourier Software using INP Input file. The 2D contours show Li atoms acquired tetrahedral sites, while, Al²⁺ atom accommodate octahedral sites in crystal environment. Thermo-gravimetric (TG) and differential thermal analysis confirms that exothermic peak at 800˚C agreeing with the processes of incomplete crystallization of spinel to full crystallization. The optical behavior of material was achieved from Photoluminescence study. The host material was excited at 349 nm and 387 nm, corresponds to ⁶H_15/2→ ⁶P_7/2, ⁴F_9/2→⁶H_13/2 and ⁶H_15/2→⁴I_13/2. The emission peak at 574 nm belongs to ⁴F_9/2→⁶H_13/2 transition of Dy³⁺ ions. The yellow band is more hypersensitive and its intensity strongly depends on the host. The Spectral Locus coordinates: X:0.471898745, Y:0.52705057 found in visible region. The blue and yellow-light emissions from Dy³⁺ produces white light for human eyes. Dy³⁺ ions (0.05 mol %) doped sample shows brighter yellow-light emission compared to blue-light component, which assured its application for White Light emitting diodes (w-LEDs).