Synthesis, structure and optical characteristics of La2Te4O11:Sm3+:A novel orange-red emitting phosphor with high thermal stability and color purity for WLEDs

Abstract

This study introduces novel reddish-orange luminescent La₂Te₄O₁₁:xSm³⁺ phosphors fabricated via a high-temperature solid-state synthesis technique. A comprehensive investigation was conducted on the X-ray diffraction (XRD) pattern, crystal structure, morphology, luminescent spectra, elemental composition, thermal stability, internal quantum efficiency, and decay lifetimes of the phosphor. The results demonstrate that the phosphor is classified within the monoclinic crystal system and corresponds to the C2/c (No.15) space group. The band gap of La₂Te₄O₁₁ was assessed using Materials Studio and quantified through diffuse reflectance spectroscopy. Under 406 nm excitation, the ideal Sm³⁺ doping concentration of 15 mol% yields strong orange-red emission at 603 nm, exhibiting excellent chromatic stability and high color purity. At 480 K, this emission performance remains highly stable, preserving 92.3 % of its room-temperature luminescence intensity, supported by a substantial activation energy (0.42 eV). Additionally, this phosphor achieves an impressive internal quantum efficiency (67.32 %). WLEDs have good correlated color temperatures (CCT) and a high color rendering index (CRI). When combined with a 406 nm ultraviolet (UV) chip and other commercial phosphors, they outperform conventional products. As a result, the La₂Te₄O₁₁:Sm³⁺ phosphors have wide application prospects for white light illumination.