Controlled synthesis of Eu³⁺-doped La₂O₂S nanophosphors by refluxing method

Abstract

A novel refluxing method is presented to synthesise Eu 3þ -doped La 2 O 2 S nanocrystalline phosphors by employing lanthanum formate, europium formate and sulphur powder as reactants and triethylene tetramine with n-dodecanethiol as solvents. The sizes and morphologies of La 2 O 2 S : Eu 3þ phosphors could be controlled from nanoflakes (10 � 2 nm in thickness), micrometre vesicles (1 mm in diameter), to spherical nanocrystals (average 100 nm in diameter) by simply adjusting the solvent ratios of n-dodecanethiol to triethylene tetramine. The photoluminescence excitation and emission spectra were used to characterise the as-synthesised nanocrystalline phosphors.

Smart facemask for wireless CO2 monitoring

“…Lanthanum oxysulfide (La 2 O 2 S) is a wide-gap semiconductor material (∼4.6 eV) suitable for doping trivalent rare-earth ions. The X-ray phosphor lanthanum oxysulfide:europium (La 2 O 2 S:Eu) was selected as luminophore, whose luminescent decay curve for 5 D 0 → 7 F 2 transition (625 nm) of Eu 3+ -doped La 2 O 2 S spherical nanocrystals shows a long decay time of 1.2 ms 23 along with high chemical and photochemical inertness. As pH indicator, α-naphtholphthalein was selected, which shows adequate p K a value for gaseous CO 2 acidity and absorption spectra to act as an acceptor of La 2 O 2 S:Eu luminescence.…”

Metal Oxysulfides: From Bulk Compounds to Nanomaterials

“…Another method was reported in 2013 by Ma et al (2013) to synthesize europium-doped lanthanum oxysulfide La 2 O 2 S:Eu. Lanthanide formates La(HCOO) 3 and Eu(HCOO) 3 were heated at 260 • C in the presence of elemental sulfur (2 equiv.…”