Oxygen Vacancy Effect on Photoluminescence Properties of Self-Activated Yttrium Tungstate

Abstract

A series of single-phase yttrium tungstate powders were synthesized through solid-state reaction under air or argon atmosphere. All powders showed broad band emission in the visible light region, and the argon-calcined samples presented strong near-infrared luminescence. Moreover, the long-wave excitation bands peaking at 340, 378, 380, 490, and 523 nm depended critically on the calcination atmosphere and temperature. The emergence of these new excitation bands was ascribed to different oxygen vacancy concentrations with the analysis of the first-principle calculation, Raman and X-ray absorption fine structure spectra. The oxygen vacancies caused the reduction of the average coordination number of tungsten, and the position of the localized energy band changed with the oxygen vacancy concentration. Finally, a schematic photoluminescence excitation model was proposed via anion and cation charge transfer. The obtained results promise to be very useful in interpreting self-activated tungstate luminescence mechanism. They can also serve as guide line for tuning the luminescence performance of yttrium tungstate and related materials.

Optical properties of black and white ZrO2 for solar receiver applications

“…In the present case, it is reasonable to hypothesize that the increase in the oxygen vacancy concentration occurring during emittance tests could alter the position of the localized energy band, as observed for other cases [24], and this resulted in a change of the optical spectrum.…”

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

“…The oxygen vacancy and local crystal structural regulation of monoclinic Y 2 WO 6 by non-activated ions have not been reported until now. Recently, we40 found that the atmosphere and calcination temperature induced the changes of oxygen vacancy concentration and tungsten coordination number in monoclinic Y 2 WO 6 , and thus affected the appearance of long-wave excitation and near-infrared emission bands. By calcining Y 2 WO 6 in the air at 1200°C, the 340 nm excitation band, caused by low-concentration oxygen-vacancy, was substantially enhanced in comparison with those calcined at high temperature or in argon.…”

Microsphere morphology tuning and photo-luminescence properties of monoclinic Y2WO6

“…The size of the precursors determines the degree of contact with oxygen during a calcination process. The powder preparation atmospheres affect the luminescence intensities [18,21,22]. So the size of precursors will affect the number and position of oxygen vacancies in the phosphors, which will then affect the luminescent properties.…”

“…By simply manipulating the calcining temperature, the excitation apex of Y 2 WO 6 at 343 nm was intensified, indicating its potential as a promising phosphor excited by near-UV LED chip [18]. In our previous study, white-emission was obtained by combining the wide-band green emission from the matrix and the sharp red emission of Sm 3 þ under 343 nm UV excitation [17].…”