Surface Sensitive Techniques for Advanced Characterization of Luminescent Materials

Swart, H.C.

doi:10.3390/ma10080906

Cited by 8 publications

(4 citation statements)

References 59 publications

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“…ZnO:Nd and ZnO:Er films are used to achieve NIR EL. The aforementioned multicolor and NIR EL originating from the impact excitation of the RE ions incorporated into the ZnO host can be activated with threshold voltages as low as ∼5 V. Another possible obstacle in the use of phosphor materials that has to be overcome is the degradation of phosphor materials with time in different environments and conditions …”

Section: Application Of Rare Earth Doped Znomentioning

confidence: 99%

Rare Earth Doped Zinc Oxide Nanophosphor Powder: A Future Material for Solid State Lighting and Solar Cells

et al. 2017

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A comprehensive review of up-conversion (UP) and down-conversion (DC) or down shifting of rare earth (RE) doped zinc oxide (ZnO) nanophosphors is presented. Research interest in the development of RE 3+ doped ZnO for UP and DC nanophosphors has been encouraged by the potential application of these materials in light emitting diodes and different types of photovoltaic cells. A range of remarkable characteristics, which are organized into different sections describing the structure, optical, and luminescence properties of these materials, are discussed in detail. Undoped ZnO has two characteristic emissions in the ultraviolet and visible regions related, respectively, to excitonic recombination and intrinsic defects. X-ray photoelectron spectroscopy (XPS) data demonstrated a correlation between the visible emission and intrinsic defects. In the case of the DC or shifting process, there was simultaneous emissions related to f → f transitions of RE ions and defects in ZnO host. These emissions were dependent on the synthesis method, annealing temperature, and RE ion concentration, among other things; only f → f transitions of RE ions were observed in the case of the UC process. These down and up conversion RE doped ZnO phosphors were evaluated for a possible application in solid state lighting and photovoltaic cells.

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Section: Application Of Rare Earth Doped Znomentioning

confidence: 99%

Rare Earth Doped Zinc Oxide Nanophosphor Powder: A Future Material for Solid State Lighting and Solar Cells

et al. 2017

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“…The EDX elemental distribution analysis were carried out with the intention to identify the presence of particular elements within commercial powder compounds, to which the luminescence effect discussed later will be assigned, rather than to identify their compositions fully, being out of this paper’s scope. Indeed, luminescent properties of pigments depend strongly on the chemical composition of the host material, as well as on the presence of particular dopant materials [23]. Due to the depicted heterogenicity, three regions of interest were selected for elemental analysis, including several pigment particles rather than particle sections, which gives a broader and more general view about the distribution of detected elements.…”

Section: Resultsmentioning

confidence: 99%

“…The presence of the rare earth element europium (Eu), known as a photoluminescent pigments’ dopant [24], was identified in the yellow-green and violet pigments. This element has strong luminescence intensity, which is affected by its oxidation state (the Eu 2+ wavelength position is matrix-sensitive, while the Eu 3+ emission position is not affected by change in the matrix [23]), as well as concentration. Besides Eu, the yellow-green pigment contains strontium (Sr), aluminium (Al) and oxygen (O), which suggest the presence of strontium aluminates.…”

Section: Resultsmentioning

confidence: 99%

Complementary Assessment of Commercial Photoluminescent Pigments Printed on Cotton Fabric

2019

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The presented study focuses on photoluminescent pigments applied on cotton fabric by a screen-printed procedure using polydimethylsiloxane (PDMS) as a binder. Microscopic data depicts irregular shapes and relatively wide size distribution (3–80 µm) of pigments. Regarding composition, the Energy-Dispersive X-ray (EDX) and Fourier Transform Infrared (FTIR) spectroscopy data complement findings suggesting the presence of Eu-doped strontium aluminate in the yellow-green, calcium aluminate in the violet pigment, and metal oxides in the blue pigment. The optical properties of pigment-enriched PDMS-coated cotton fabric were assessed and reflectance intensity was found to be concentration-dependent only in the blue pigment. The luminescence decay data show that luminescence intensity decreased with the reduction of pigment concentration in the following order, yellow-green > blue > violet pigments. Relying on absorption and emission data of powdered pigments, the confocal microscopy enables visualization of the pigments’ distribution within a 3D image projection. This identifies the most homogeneous distribution in the case of the blue pigment, as well as the presence of a continuous fluorescing signal in the z projection when 5% pigment was used. This was, for the first time, presented as a powerful tool for non-destructive visualization of photoluminescent pigments’ spatial distribution when printed on textile (cotton) fabric. Finally, the photoluminescent PDMS coating demonstrates high washing and abrasion resistance, contributing to overall functionality of printed cotton fabrics when commercial types of pigments are applied.

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“…Nevertheless, neither TOF-MS nor SIMS is sufficiently sensitive to distinguish chemical forms of elements. Such information is attainable via X-ray photoelectron spectroscopy (XPS); 42 however, these elemental composition and chemical form measurements are restricted to the particle's subsurface which extends mere nanometers beneath the surface, rendering chemical state measurements at greater depths unattainable. Chemical analysis of micrometersized particulates thus requires new approaches that can overcome limitations associated with microscope sensitivity and sample thickness.…”

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confidence: 99%

Single-Particle Analysis for Structure and Iron Chemistry of Atmospheric Particulate Matter

et al. 2019

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As a representative transition metal, iron plays a key role in chemical activities of atmospheric particulate matter (PM), being involved in particle-related free radical generation and adverse health effects. However, limited understanding of the structure and properties of individual micrometer-sized particulates obscures investigating the contributions of iron toward chemical activities. Here, we describe multidimensional analytical strategies to characterize the mass, spatial distribution, and chemical forms of iron in single haze particles using synchrotron radiation techniques. We first used X-ray fluorescence imaging to quantify the masses of multiple metals and yielded distribution maps of transition metals, which revealed the types of elements that tend to occur together. Additionally, we employed nanocomputed tomography to assess the spatial distribution of iron and observed that iron exists as small aggregates and is concentrated primarily in subsurface regions. We also combined X-ray absorption near structures with scanning transmission X-ray microscopy to quantify the ferrous and ferric forms and mapped their distributions in individual particles, which probably attribute chemical activity of iron. In conclusion, we demonstrated the power of synchrotron radiation-based techniques to study heretofore inaccessible chemical information in single haze particles, which may provide important clues about iron chemistry as a source of Fenton reactions and health effects. The multifaceted analytical approaches exhibit high sensitivity (subfemtogram per particle or ∼0.2 fg/μm2) toward multiple elements and are promising to be used for studying other concepts such as the solubility of aerosol iron, the heterogeneous oxidation of organic matters and SO2, and the formation and the aging of haze particles.

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Surface Sensitive Techniques for Advanced Characterization of Luminescent Materials

Cited by 8 publications

References 59 publications

Rare Earth Doped Zinc Oxide Nanophosphor Powder: A Future Material for Solid State Lighting and Solar Cells

Rare Earth Doped Zinc Oxide Nanophosphor Powder: A Future Material for Solid State Lighting and Solar Cells

Complementary Assessment of Commercial Photoluminescent Pigments Printed on Cotton Fabric

Single-Particle Analysis for Structure and Iron Chemistry of Atmospheric Particulate Matter

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