Exploring single rare earth doped nanophosphor for efficient white emission through codoping of Na+ and Bi3+ ions into Dy3+ activated LaPO4

• Published in: Inorganic chemistry communications 2024-10, Vol.168, p.112888, Article 112888
• Main Authors: Chandran, Aswathy R, Ann Jacob, Linju, Paul, Issac, Jose, Gijo
• Format: Article
• Language: English
• Subjects: Concentration quenching; Photoluminescence; Rare earth phosphate; Solution combusting reaction; White LED applications
• ISSN: 1387-7003
• DOI: 10.1016/j.inoche.2024.112888

[Display omitted] •Nanocrystalline LaPO4: Dy3+, Na+, Bi3+ was prepared using citrate based hydrothermal method and the structural characterisation was confirmed using XRD.•The photoluminescence and CIE chromaticity analysis corroborates the potential utility of the prepared sample for cool white light emission under near UV excitation and warm white light emission under blue LED excitation.•The intensity of both blue and yellow emissions increases up to x = 0.03 mol and then decreases rapidly due concentration quenching. Using the simple hydrothermal technique, high-purity nanocrystalline Na+ and Bi3+ co-doped Dy3+ activated LaPO4 was effectively prepared. The structural characterisation of the prepared samples was carried out using XRD, EDS, SEM and FTIR analysis. The existence of Na+, Dy3+, La3+, P5+, O2– and Bi3+ was demonstrated using EDS analysis. The direct band gap value of 4.72 eV is obtained from UV visible absorption spectrum and infer that the doped samples are suitable for optical applications. The photoluminescence excitation spectrum monitored at 474 nm and 570 nm emission, the Na+ and Bi3+ co-doped Dy3+ activated LaPO4 exhibit narrow, and intense characteristics f-f peak of Dy3+ ion at 349 nm, 363 nm, 386 nm and 452 nm. Photoluminescence emission spectrum, monitored under 349 nm, 363 nm and 386 nm shows high intense sharp blue emission peaks of Dy3+ with stark splitting at 475 nm, 478 nm, and 486 nm, yellow emission at 571 nm and 580 nm and a very feeble peak at 658 nm in the red region. When the sample is excited at 452 nm only a yellow band is present. Since the intensity of blue and yellow emission in this host matrix is so high and nearly equal, it is appropriate for cool white emission under 350 nm, 363 nm and 386 nm (near UV) excitation and under 452 nm (blue LED) excitation the prepared phosphor may emerge as highly efficient warm white light emitter suitable for general solid-state lighting applications, which can be further confirmed by CIE chromaticity analysis of the prepared sample. In photoluminescence excitation and emission spectra intensities of peaks of the samples with Bi3+ are more intense, this confirms the positive impact of co-doping of Bi3+ into the sample. The Q value from the Dexter’s formula is calculated as an average of 6.4 and is very close to 6 indicates that the interaction is dipole − dipole, which causes the non-radiative energy migration among the Dy3+ ions in the sample. The lifetime of characteristic yello