Facile synthesis and luminescence studies of nanocrystalline red emitting Cr:ZnAl 2 O 4 phosphor

Menon, Samvit G.; Hebbar, Deepak N.; Kulkarni, Suresh D.; Choudhari, K.S.; Chidangil, Santhosh

doi:10.1016/j.materresbull.2016.10.009

Cited by 58 publications

(24 citation statements)

References 50 publications

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“…The band at 370 nm intensifies with annealing up to 800°C, beyond which it gradually disappears. With annealing, Cr 3+ ions are redistributed in the matrix, leading to a gradual change in material color from colorless (as‐prepared) to greenish (800°C) and finally to pale pink (1200°C), consistent with our previous work . The band gap of the as‐prepared sample is 3.42 eV, while that of the annealed samples is ~3 eV (Figure ).…”

Section: Resultssupporting

confidence: 86%

“…The present work demonstrates that microwave irradiation can be used to synthesize fine‐grained refractory oxides at temperatures as low as 220°C relatively quickly (40‐60 minutes), the rapidity stemming from the dielectric heating at the molecular level that leads to uniform heating and high local temperatures . Considering that the material is a ceramic, 220°C is quite low (compared to co‐precipitation method) for synthesizing crystalline material and much faster compared to other methods. In addition, the use of metalorganic precursors favors the formation of oxide materials through nucleophilic attack of solvent on the carbonyl group of the acetylacetonate ligand, the subsequent hydrolytic formation of metal hydroxide intermediates and their polycondensation to form the metal oxides.…”

Section: Resultsmentioning

confidence: 79%

“…The process requires high temperature and long reaction times, undesirable both from environmental and technological points of view. Therefore, wet chemical methods such as sol‐gel, combustion, co‐precipitation, and hydrothermal have been employed. In the sol‐gel method, the main disadvantages are the possibility of formation of multiphase materials and the long reaction time.…”

Section: Introductionmentioning

confidence: 99%

“…Though the hydrothermal process is a most promising method for preparing ceramic nanoparticles, the processing is time‐consuming and energy‐intensive. The pH‐dependent co‐precipitation method requires >10 hours at temperatures >500°C for the formation of spinel phase, making this process technologically disadvantageous and undesirable . Thus, there is a need for developing a swifter and more energy efficient method for the synthesis of oxide spinels.…”

Section: Introductionmentioning

confidence: 99%

“…We report here a simple and novel microwave‐assisted synthesis of Cr:ZnAl 2 O 4 nanoparticles using metalorganic precursors—a swift, pH independent technique that gives phase‐pure, nanocrystalline Cr:ZnAl 2 O 4 in the as‐prepared form. The effects of annealing on the structural and optical properties of the spinel oxide have been studied and compared with our earlier work . To understand the interaction between the dopant and the ZnAl 2 O 4 host, a detailed study on luminescence properties has been carried out.…”

Section: Introductionmentioning

confidence: 99%

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Cr‐doped ZnAl₂O₄: Microwave solution route for ceramic nanoparticles from metalorganic complexes in minutes

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A combination of microwave irradiation and metalorganic precursors in solution was used for the synthesis of Cr:ZnAl2O4 nanoparticles with high yields (~92%). Though the spinel phase is formed after ~40 minutes, 60 minutes of microwave irradiation was required for the complete transformation of precursors into the spinel. The as‐prepared material is nanocrystalline and phase‐pure and was subjected to annealing in air at different temperatures. Annealing improved the crystallinity, and the material turned pink at 1200°C. The structural and optical properties were investigated by XRD, HR‐TEM, FE‐SEM, FT‐IR, diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The two bands in the excitation spectra (400 and 540 nm) became more intense as the annealing temperature was raised. The 400 nm band was asymmetric and consisted of two peaks, suggesting a trigonal distortion. The emission spectra consisted of a zero phonon line (ZPL), along with its associated multi‐phonon side bands. The high Dq/B (3.21) suggested the presence of Cr3+ in a strong crystal field. With annealing, the emission lifetimes increased from ~7 to ~34 ms. This work demonstrates rapid, low‐temperature synthesis of a red‐emitting phosphor, with potential applications in bio‐imaging, sensors, and lighting.

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cr‐doped ZnAl₂O₄: Microwave solution route for ceramic nanoparticles from metalorganic complexes in minutes

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Luminescent and Photonic Materials for Sensing Applications

Khalid,

Zulfiqar,

Shehzad

et al. 2023

Organic and Inorganic Materials Based Sensors

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Mechanism of Magnesium Transport in Spinel Chalcogenides

Sotoudeh

Dillenz

Groß

2021

Adv Energy and Sustain Res

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Â 10 À4 % of Li. The ionic radii of Mg 2þ , 0.86 Å, and Li þ , 0.90 Å, are rather similar, [1] but Mg has the advantage of being a bivalent ion, which leads to a higher volumetric capacity of Mg metal anodes compared to Li, 3833 mAh cm À3 versus 2062 mAh cm À3 , and also to a low reduction potential of À2.37 V versus the standard hydrogen electrode (SHE) compared to À3.05 V of Li. [9,10] Furthermore, Mg-ion batteries (MIBs) exhibit a low tendency for dendrite formation [11][12][13][14][15] and a high melting point.A high multivalent ionic conductivity of 1-10 mS cm À1 has been achieved in MIBs at high temperatures. [16,17] However, a major problem for MIBs lies in the sluggish kinetics during intercalation at room temperature. [2,18] It should be noted that the design of chemically stable electrodes with high ionic conductivity is highly desirable, [2,[19][20][21][22][23] as a low ionic mobility can severely limit the performance of batteries.To address the slow migration of Mg ions in cathode materials at low temperatures, Chevrel phases and layered and spinel TiS 2 structures have been studied in detail. [24] A Mg-ion migration barrier of about 550 meV was found in cubic Ti 2 S 4 using galvanostatic intermittent titration technique measurements. Note that typically maximum migration barriers of %525 meV for micron-sized particles and %650 meV for nanosized particles are assumed to be compatible with an adequate battery operation. [25] Studies on the sulfide and selenide spinel frameworks indicate low-energy barriers for Mgion diffusion comparable to those of LIBs. [26] In contrast, oxide spinel cathode materials exhibit high migration barriers for Mg ions, which are caused by the relatively strong Coulombic attraction between the guest Mg 2þ and host oxygen lattice, [23] which leads to a lower ion mobility. The smaller electronegativity of sulfur and selenium lattices enlarges the lattice constant of these materials and thus also their ion mobility as typically diffusion barriers become smaller for larger lattice constants. Nevertheless, the increase of the ion mobility through the lowering of diffusion barriers is also accompanied by lower Mg insertion energies into the spinel structures, which lowers the voltage [27,28] and thus causes a reduction of the energy densities of chalcogenide materials.Recently, MgSc 2 Se 4 has been found to be a super ionic conductor exhibiting a high Mg-ion conductivity of 0.1 mS cm À1 at room temperature. [26] This high ion mobility not only makes MgSc 2 Se 4 a promising cathode material for MIBs, but also suggests that it could be used as a solid electrolyte. However, solid

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Facile synthesis and luminescence studies of nanocrystalline red emitting Cr:ZnAl 2 O 4 phosphor

Cited by 58 publications

References 50 publications

Cr‐doped ZnAl₂O₄: Microwave solution route for ceramic nanoparticles from metalorganic complexes in minutes

Cr‐doped ZnAl₂O₄: Microwave solution route for ceramic nanoparticles from metalorganic complexes in minutes

Luminescent and Photonic Materials for Sensing Applications

Mechanism of Magnesium Transport in Spinel Chalcogenides

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Facile synthesis and luminescence studies of nanocrystalline red emitting Cr:ZnAl 2 O 4 phosphor

Cited by 58 publications

References 50 publications

Cr‐doped ZnAl2O4: Microwave solution route for ceramic nanoparticles from metalorganic complexes in minutes

Cr‐doped ZnAl2O4: Microwave solution route for ceramic nanoparticles from metalorganic complexes in minutes

Luminescent and Photonic Materials for Sensing Applications

Mechanism of Magnesium Transport in Spinel Chalcogenides

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Product

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Cr‐doped ZnAl₂O₄: Microwave solution route for ceramic nanoparticles from metalorganic complexes in minutes

Cr‐doped ZnAl₂O₄: Microwave solution route for ceramic nanoparticles from metalorganic complexes in minutes