Fabrication of alkali metal sulfate–doped zinc tungstate and their photoluminescence

Lorchirachoonkul, P.; Nakata, Masaya; Okamoto, Takuya

doi:10.1016/j.jlumin.2018.11.025

Cited by 2 publications

(1 citation statement)

References 21 publications

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“…Recently, ternary-tungstate-based complex oxides have attracted the attention of researchers as potential candidates for efficient photocatalytic applications, including energy conversion and environmental purification, owing to their striking features such as low cost, environmental efficiency, and high stability under acidic and oxidative conditions [164][165][166][167] . As a representative member of this group, zinc tungstate (ZnWO 4 ) has received considerable attention, owing to its high thermal stability, excellent optical and electrical properties, and wide range of applications from photocatalytic, photoluminescent, to Li-battery anode materials [168][169][170][171] . These ZnWO 4 characteristics result from its relatively high valence band and wide band gap 172,173 , which can generate OH• with a strong oxidizing property to inactivate bacteria 174 .…”

Section: Zinc Tungstate (Znwo 4 )mentioning

confidence: 99%

Reading at exposed surfaces: theoretical insights into photocatalytic activity of ZnWO4

et al. 2018

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Understanding the criteria warranting the existence, stability, and activity of a given configuration of atoms has pivotal relevance in chemical and materials science. Photocatalysts, traditionally semiconductors, are essential for processes ranging from water purification to water splitting, air filtration, and surgical instrument sterilization, and harvest optical energy to drive chemical reactions. These semiconductors harvest optical energy to drive chemical reactions. With chemical reactions dictated by atomic and molecular interactions at the nanoscale, examining these processes with near-atomic resolution is necessary to understand photochemical processes in depth and to improve materials for next-generation catalysts. The performance and key electronic properties of semiconductors are dictated by the interplay between the surface chemistry and morphology, whose manipulation has inspired experimental and theoretical researchers. This interplay has been clarified by theoretical studies based on atomic-scale modelling with particular attention given to two sets of degreesof-freedom: the atomic positions and chemical configuration. This perspective article presents the major computational challenges and modern methodological strategies toward advancing the field. The ZnWO 4 material was selected as a case study, and the key concepts developed in recent years are discussed to clarify the morphology, i.e., the exposed surfaces of materials, and explain its functional properties or performance. First-principle calculations capture the geometric and electronic effects on the photocatalytic activity in agreement with experimental data. Indeed, important and often surprising structure-function relations have been observed based in depth atomistic modelling on morphological analysis. An overview of past achievements and future directions is provided according to the authors' outlook.

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Section: Zinc Tungstate (Znwo 4 )mentioning

confidence: 99%

Reading at exposed surfaces: theoretical insights into photocatalytic activity of ZnWO4

et al. 2018

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Composite scintillators based on ZnWO4:Me+ micropowders obtained by solid-state synthesis

Tinkova,

Tupitsyna,

Yakubovskaya

et al. 2022

The Journal of v. N. Karazin Kharkiv National University, Series "Physics"

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The paper considers the possibility of using the method of heterovalent doping to improve the functional characteristics (light output and afterglow level) of composite scintillators based on ZnWO4 micropowder obtained by solid-stase synthesis. LiNO3, Li2SO4, Cs2SO4, Rb2SO4 were added to the mixture of initial ZnO and WO3 oxides in the amount of 0.003 wt. %. The synthesis was carried out in air at a temperature of 950 °C for 30 hours. The study of the morphology of the obtained powders was carried out by scanning electron microscopy (SEM). It has been shown that the grain size of the synthesized powders dependence on a greater extent by the radius of the cation replacing Zn2+ than by the presence of a mineralizer with a low melting point. The studied anions do not affect the synthesis process, and when ZnSO4 is added, the size of the obtained grains is similar to the nominally pure synthesized ZnWO4 (2-5 μm). When ZnWO4 is doped with 20% less Li+ relative to Zn2+, regardless of the form of introduction (anionic component), the average grain size increases by 4 times. When ZnWO4 doped with Rb+ and Cs+, which are twice as large as Zn2+, grains increase by a factor of 20. It happened because of a significant loosening of the crystal lattice formed by zero-dimensional defects, which contributes to better diffusion of reagents and acceleration of the synthesis process. The study of X-ray luminescence showed that the spectra of the synthesized powders coincide in terms of the peak position with the spectrum of the ZnWO4 single crystal, which corresponds to the emission on the WO6 6- oxyanion complex. The intensity of the bands increases with increasing dopant’s cationic radius: Li+ → Rb+ → Cs+. The maximum X-ray luminescence intensity is observed for the ZnWO4:Cs+ micropowder, which is two times higher than the intensity of the undoped ZnWO4 micropowder. This is due to a rather high degree of deformation of the structure of the WO6 emission center, which, in turn, affects the luminescent properties of the material. Composite samples based on the synthesized micropowders were prepared using SKTN optically transparent rubber as a binder in an amount of 50 wt.%. The results of measurements of the relative light output of composite scintillators based on ZnWO4:Me+ correlate with the results of measurements of the X-ray luminescence intensity of the synthesized powders. An increase in the value of the light output with an increase in the radius of the dopant cation is observed. Measurement of the afterglow level showed that the use of the heterovalent doping method, namely Me+ in our work, is an effective way to improve the scintillation parameters of crystalline materials. Composite scintillators based on ZnWO4:Cs+ and ZnWO4:Rb+ demonstrate the values of light output and afterglow at the level of a composite from a crushed ZnWO4 single crystal, and no worse than a single crystal ZnWO4 sample. The obtained materials are promising for use as scintillation detectors in computed tomography and digital radiography devices.

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Fabrication of alkali metal sulfate–doped zinc tungstate and their photoluminescence

Cited by 2 publications

References 21 publications

Reading at exposed surfaces: theoretical insights into photocatalytic activity of ZnWO4

Reading at exposed surfaces: theoretical insights into photocatalytic activity of ZnWO4

Composite scintillators based on ZnWO4:Me+ micropowders obtained by solid-state synthesis

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