Vacancy defects and defect clusters in alkali metal ion-doped MgO nanocrystallites studied by positron annihilation and photoluminescence spectroscopy

Sellaiyan, S.; Uedono, Akira; Sivaji, K.; Priscilla, S. Janet; Sivasankari, J.; Selvalakshmi, T.

doi:10.1007/s00339-016-0440-x

Cited by 10 publications

(6 citation statements)

References 45 publications

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“…MgO nanostructures showed emission in the UV-Vis-NIR range [ 29 , 30 , 31 , 32 , 33 , 34 ]. The observed emission can be explained by structural defects [ 29 ].…”

Section: Resultsmentioning

confidence: 99%

“…The observed emission can be explained by structural defects [ 29 ]. PL peaks, observed in the range 380–520 nm, are associated with F/F+ centers (alkali ions/atoms) and oxygen vacancies [ 29 , 30 , 31 , 32 , 33 , 34 ]. The observed PL emission in the range of 600–800 nm is attributed to surface structural defects, such as oxygen vacancies and interstitials [ 29 , 30 , 31 , 32 , 33 ].…”

Section: Resultsmentioning

confidence: 99%

“…Mg PEO samples showed four characteristic emission peaks, centered at 360-380, 450, 500 and 660 nm. MgO nanostructures showed emission in the UV-Vis-NIR range [29][30][31][32][33][34]. The observed emission can be explained by structural defects [29].…”

Section: Coatings Characterizationmentioning

confidence: 96%

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Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions

et al. 2021

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The biodegradable metals, including magnesium (Mg), are a convenient alternative to permanent metals but fast uncontrolled corrosion limited wide clinical application. Formation of a barrier coating on Mg alloys could be a successful strategy for the production of a stable external layer that prevents fast corrosion. Our research was aimed to develop an Mg stable oxide coating using plasma electrolytic oxidation (PEO) in silicate-based solutions. 99.9% pure Mg alloy was anodized in electrolytes contained mixtures of sodium silicate and sodium fluoride, calcium hydroxide and sodium hydroxide. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), contact angle (CA), Photoluminescence analysis and immersion tests were performed to assess structural and long-term corrosion properties of the new coating. Biocompatibility and antibacterial potential of the new coating were evaluated using U2OS cell culture and the gram-positive Staphylococcus aureus (S. aureus, strain B 918). PEO provided the formation of a porous oxide layer with relatively high roughness. It was shown that Ca(OH)2 was a crucial compound for oxidation and surface modification of Mg implants, treated with the PEO method. The addition of Ca2+ ions resulted in more intense oxidation of the Mg surface and growth of the oxide layer with a higher active surface area. Cell culture experiments demonstrated appropriate cell adhesion to all investigated coatings with a significantly better proliferation rate for the samples treated in Ca(OH)2-containing electrolyte. In contrast, NaOH-based electrolyte provided more relevant antibacterial effects but did not support cell proliferation. In conclusion, it should be noted that PEO of Mg alloy in silicate baths containing Ca(OH)2 provided the formation of stable biocompatible oxide coatings that could be used in the development of commercial degradable implants.

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“…MgO nanostructures showed emission in the UV-Vis-NIR range [ 29 , 30 , 31 , 32 , 33 , 34 ]. The observed emission can be explained by structural defects [ 29 ].…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions

et al. 2021

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“…As the MgO is a wide band gap insulator (band gap is ∼7.8 eV), the above observed emissions are possible only if various traps or defect states that reduce the photon excitation energy to induce visible emissions with sub band gap excitations are present. The various possible defects are oxygen vacancy (F-centers), magnesium vacancy (V-centers), oxygen interstitial, magnesium interstitials, or different stacking fault that are produced during the synthesis of the MgO nanocubes at high temperature. − From the XPS study, it is confirmed that most of the defects are oxygen defects, causing the emissions in the visible region. When MgO-600 and MgO-1200 are annealed in oxygen-rich environments at high temperature for 3 h, it is found that the emissions in the visible region (blue and orange-red emission) are either suppressed or disappeared without change in the phase or morphology of the nanocubes (Figure S4).…”

Section: Resultsmentioning

confidence: 99%

MgO Nanocubes as Self-Calibrating Optical Probes for Efficient Ratiometric Detection of Picric Acid in the Solid State

Senapati

2018

ACS Sustainable Chem. Eng.

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EDS spectrum of the MgO-600 nanocubes ……………………………………… Figure S1 TGA curves of MgO-600 and MgO-1200 ……………………………………….. Figure S2 PLE spectra of MgO-600 and MgO-1200 ……………………………………….. Figure S3 XRD patterns of the MgO-600 (O) and MgO-1200 (O) …………………………. Figure S4 Room temperature PL spectra of the MgO-600 (O) and MgO-1200 (O) ………... Figure S5 Variation of integral peak intensities with 355 nm excitation …………………… Figure S6 S2 Variation of integral peak intensity ratio with 355 nm excitation ………………... Figure S7 PL spectra in the presence of various nitro compounds ………………………….. Figure S8 Variation of integral PL intensity ratio for different nitro compounds …………... Figure S9 PL intensity ratio and quenching efficiency for different nitro compounds with PA Figure S10 Temporal response curve ………………………………………………………….. Figure S11 Variation of PL spectrum with 532 nm excitation ………………………………… Figure S12 Variation of integral peak intensities with 532 nm excitation ………………………Figure S13 Variation of integral peak intensity ratio with 532 nm excitation …………………. Figure S14 PA sensing for MgO-1200 (O-5h) with 532 nm excitation ………………………... Figure S15 SEM image and XRD patterns of the washed nanocubes ………………………… Figure S16 Absorption and emission spectra of nitro compounds and MgO nanocubes ……… Figure S17 Time resolve PL measurement …………………………………………………….. Figure S18 HOMO energy levels of MgO and different nitro compounds ……………………. Figure S19 Comparison table for quenching constant and limit of detection …………………. Table S1 Comparison table for response time ……………………………………………… Table S2 Comparison of LOD with different reported sensors …………………………….. Table-S3 Comparison table for excited state life time ………………………………………. Table S4

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“…For example; thin films and nanoparticles of magnetism oxide show magnetism associated with surface and extended defects [ 69 , 70 , 71 ]. Moreover, luminescent behavior of nanostructured MgO is tailored by controlling the defect states in the material [ 72 , 73 , 74 ].…”

Section: Introductionmentioning

confidence: 99%

Approaches to synthesize MgO nanostructures for diverse applications

Singh

Sharma

et al. 2020

Heliyon

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Magnesium oxide remained interesting from long time for several important phenomena like; defect induced magnetism, spin electron reflectivity, broad laser emission etc. Moreover, nanostructures of this material exhibited suitability for different kinds of applications ranging from wastewater treatment to spintronics depending upon their shape and size. In this way, researchers had grown nanostructures in the form of nanoparticles, thin films, nanotubes, nanowalls, nanobelts. Though nanoparticles and thin films are well known form of nanostructures and wide variety of synthesis approaches are available, however, limited methodology for other nanostructures are available. In order to grow these nanostructures in an optimized way an understanding of these methods is essential. Thus, this review article depicts an overview of various approaches for design of different kinds of nanostructures.

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Vacancy defects and defect clusters in alkali metal ion-doped MgO nanocrystallites studied by positron annihilation and photoluminescence spectroscopy

Cited by 10 publications

References 45 publications

Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions

Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions

MgO Nanocubes as Self-Calibrating Optical Probes for Efficient Ratiometric Detection of Picric Acid in the Solid State

Approaches to synthesize MgO nanostructures for diverse applications

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