Raman scattering and red emission of Mn4+ in La0.7Sr0.25Na0.05Mn0.7Ti0.3O3 manganite phosphor for LED applications

Abstract

The vibrational and optical properties of an La_0.7Sr_0.25Na_0.05Mn_0.7Ti_0.3O₃ (LSNMT) polycrystalline sample produced via a solid-state reaction were studied. The Raman spectrum at room temperature reveals the chemical disorder in our compound. The optical gap and Urbach energy were estimated on the basis of the absorption spectrum. Moreover, the polycrystalline manganite radiates in the near-infrared light (1000 nm) with 514.5 nm light excitation and in the temperature range from 10 K to 300 K. Crystal field analysis suggests that only the Mn⁴⁺ luminescent center is found in LSNMT. The measured activation proves that our compound possesses good thermostability. The chromaticity coordinates prove that the emission of the LSNMT sample occurs in the near-infrared region. All analytical findings demonstrate that LSNMT manganite has substantial prospective applications in white luminescent devices.