Tuning oxygen vacancy photoluminescence in monoclinic Y2WO6 by selectively occupying yttrium sites using lanthanum

Abstract

The effect of isovalent lanthanum (La) doping on the monoclinic Y2WO6 photoluminescence was studied. Introducing the non-activated La3+ into Y2WO6 brings new excitation bands from violet to visible regions and strong near-infrared emission, while the bands position and intensity depend on the doping concentration. It is interesting to find that doping La3+ into Y2WO6 promotes the oxygen vacancy formation according to the first-principle calculation, Raman spectrum, and synchrotron radiation analysis. Through the Rietveld refinement and X-ray photoelectron spectroscopy results, La3+ is found to mainly occupy the Y2 (2f) site in low-concentration doped samples. With increasing doping concentration, the La3+ occupation number at the Y3 (4g) site increases faster than those at the Y1 (2e) and Y2 (2f) sites. When La3+ occupies different Y sites, the localized energy states caused by the oxygen vacancy pair change their position in the forbidden band, inducing the variation of the excitation and emission bands. This research proposes a feasible method to tune the oxygen vacancy emission, eliminating the challenge of precisely controlling the calcination atmosphere.

Interfacial Phenomenon and Nanostructural Enhancements in Palladium Loaded Lanthanum Hydroxide Nanorods for Heterogeneous Catalytic Applications

“…The La3d region has spin-orbit components and each spin-orbit component is further split by multiplet splitting. La(OH) 3 shows four components and the intensity ratio of La3d 5/2 is found to be DE/eV = 3.9, which is characteristic to Lanthanum hydroxide 29 . The corresponding O 1s spectrum is displayed in Fig.…”

Solution‐Processable, High‐Performance Flexible Electroluminescent Devices Based on High‐k Nanodielectrics

“…In the high‐resolution spectrum of La 3d (Figure e), two peaks at 834 and 851 eV are attributed to La 3d 5/2 and La 3d 3/2 . The binding energy peak of La 3d splits into two peaks due to the spin–orbit interaction that separates La 3d 5/2 and La 3d 3/2 electrons . This split is caused by the transfer of an electron from O to the f orbital of La, indicating La insertion into the BTO crystal structure, which confirms the presence of La (Figure e).…”

Photoluminescence and Scintillation Modulation Upon UV/X‐ray‐Induced Photochromism in Europium Tungstate Phosphors

“…The magnification of the region between 330 and 500 nm (Figure (a), inset) shows a second band assigned to W VI ←O ‐II LMCT transitions. The emission spectra under UV (λ ex = 260 nm, Figure (a), blue line) and X‐rays (CuKα, Figure (a), red line) excitations show the same spectral profile, a broad band with maximum in the green region assigned to charge transfer transitions into the [WO 6 ] 6‐ tungstate group ,,,,. The same profile is verified to the sample prepared with citric acid 0.1 mol L ‐1 .…”

“…Tungstates, specifically, are also a kind of self‐activated luminescent material. Their luminescent properties are mainly originated from charge transfer transitions in the WO 4 2‐ /WO 6 6‐ lattice group which gives rise to a broad emission band in the visible range. Besides that, the high atomic number of W (Z = 183) and the high density of its compounds, which results in a large X‐ray absorption coefficient,, enable their use as X‐ray phosphors and scintillators ,.…”