Study of Lumino Structural Properties of Rare Earth Ions Doped Niobate Phosphors for Opto Electronic Applications

Abstract

This thesis investigates the synthesis, structural characterization, and photoluminescence properties of Dy3+ and Eu3+ doped Na3Ba2LaNb10O30 phosphors for solid-state lighting (SSL) and optoelectronic applications, with a focus on white light-emitting diodes (wLEDs). The phosphors were synthesized using the solid-state reaction method, ensuring high phase purity and thermal stability of the host lattice. Structural and morphological analyses were performed using X-ray diffraction (XRD), Rietveld refinement, field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and UV visible diffuse reflectance spectroscopy (DRS). newlinePhotoluminescence (PL) studies revealed characteristic blue (and#8764;480 nm) and yellow (and#8764;575 nm) emissions from Dy3+ doped phosphors, producing white light, while Eu3+ doped samples exhibited intense red emission at and#8764;615 nm due to the and#8309;Dand#8320; and#8594; and#8311;Fand#8322; transition. Optimal doping concentrations of 7 mol% (Dy3+) and 9 mol% (Eu3+) were identified, beyond which concentration quenching occurred. The chromaticity coordinates and correlated color temperature (CCT) values were calculated using the CIE 1931 color space, confirming high color purity and suitability for wLED applications. Time-resolved photoluminescence decay (TRPL) measurements showed lifetimes of and#8764;300 and#956;s (Dy3+) and and#8764;800 and#956;s (Eu3+), indicating long-lasting luminescence. Internal quantum efficiency (IQE) values of 45% for Dy³and#8314; and 78% for Eu3+ doped phosphors were achieved, making them competitive with commercial phosphors. newlineThis work demonstrates that Na3Ba2LaNb10O30:Dy3+/Eu3+ phosphors are cost-effective, efficient, and environmentally friendly materials for SSL. Future prospects include optimizing synthesis parameters, exploring co-doping strategies, and integrating these phosphors into prototype LED devices for enhanced performance. newline newline