Study on the optical spectra of MgAl<sub>2</sub>O<sub>4</sub> with oxygen vacancies

Li, Qiuyue; Liu, Tingyu; Xu, Xun; Wang, Xueli; Guo, Rui; Jiao, Xuping; Lu, Yazhou

doi:10.1080/10667857.2020.1750163

Cited by 11 publications

(4 citation statements)

References 40 publications

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“…A narrow green emission peak at 542 nm and a broad emission band with maxima at 378 nm were observed. The broad emission band could have originated from the oxygen vacancies (V •• O ) such as F, F + centers and barium vacancy [21][22][23]35]. The defects were probably oxygen or barium vacancies caused by the evaporation of BaO due to the high temperatures achieved during the combustion synthesis [19,20].…”

Section: Resultsmentioning

confidence: 99%

Charge carrier trapping processes in un-doped and BaAl₂O₄:Eu³⁺ nanophosphor for thermoluminescent dosimeter applications

Shivaramu

Coetsee

Roos

et al. 2020

J. Phys. D: Appl. Phys.

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The thermoluminescence (TL) mechanism for un-doped and europium (Eu 3+ ) doped barium aluminate (BaAl 2 O 4 ) were investigated and the location of energy levels for electrons/holes traps were determined in the aluminate for TL dosimetry applications. The solution combustion technique was used to synthesize the un-doped and Eu 3+ doped BaAl 2 O 4 nanopowders. X-ray diffraction showed a hexagonal crystal structure with the space group P6 3 . The average crystallite size were found to be 50 nm and between 41 and 61 nm for un-doped and doped samples. Scanning electron microscopy showed irregular spherical and needle shapes for the un-doped and doped samples. The Kubelka-Munk function was used to calculate the optical bandgap values of 5.47 and 5.26 eV, for the un-doped and doped samples, from the diffuse reflectance spectra. The fitted x-ray photoelectron spectroscopy data demonstrated that Ba occupied two different sites, Ba1 and Ba2. Time-of-flight secondary ion mass spectroscopy in spectral mode showed the formation of the crystal lattice with the presence of the dopant. The photoluminescent and cathodoluminescent spectra were characterized by the 5 D 0 -7 F J transitions (J = 1, 2, 3, 4) of Eu 3+ with the dominate emission obtained at J = 2. A strong TL glow curve with peaks at 397 and 453 K were observed for the un-doped and doped nanopowders after irradiation with γ-rays. The doped nanopowders showed the highest TL intensity because doping with Eu 3+ lead to the formation of additional trapped electrons and holes. The un-doped sample showed strong green (546 nm) TL emission due to the presence of a V k 3+ center. Whereas the Eu doped nanopowders exhibited strong TL emission at 615 nm.

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Section: Resultsmentioning

confidence: 99%

Charge carrier trapping processes in un-doped and BaAl₂O₄:Eu³⁺ nanophosphor for thermoluminescent dosimeter applications

Shivaramu

Coetsee

Roos

et al. 2020

J. Phys. D: Appl. Phys.

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“…MgAl2O4 shows some excellent properties such as exceptional structural, chemical stability, good optical transmission & high energy radiation and corrosion resistance. It can be used to manufacture high-performance optoelectronic devices (light-emitting diodes, lasers, solar cells & display devices), temperature and humidity sensing materials (thermometers & humidity sensors) [2,3].It is quite known that in oxide based inorganic materials, like MAO, defects play a key role to influence their structural, electronic, magnetic, dielectric and optical properties. When MAO spinel heated at high temperature, it has the ability to produce a great number of oxygen vacancies or luminescent centers.…”

Section: Introductionmentioning

confidence: 99%

Defect induced emission of MgAl₂O₄ sintered at high temperature

Kaur

Rani

2022

J. Phys.: Conf. Ser.

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MgAl2O4 (MAO) spinel has been considered as one of the excellent optoelectronic material due to its excellent mechanical strength and transparency in visible region to IR region. Many studies reported that MAO has F centers generated due to high temperature sintering which resulted in visible emission. The aim of present study is to explore MAO sintered at high temperature for white light emission. MAO was synthesized by sol-gel method sintered at 1400°C high temperature for 4hrs. Prepared MAO was characterized by various characterization techniques; Fourier transfer infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) with the energy dispersive X-ray spectroscopy (EDX) and Fluorescence spectroscopy (FS). Peak at 674cm-1 in FTIR confirmed the formation of MAO. SEM Images showed the agglomeration of particles due to high temperature sintering Emission properties of MAO was studied by Florescence spectroscopy. MAO was excited by UV light. The emission spectra showed multicolor emission in visible region due to generation of F centers in the bandgap proving MAO as excellent material for white light emission.

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“…Nevertheless, the doping of such ceramics not only leads to the modification of their luminescent properties and changes in phase composition, but also causes structural transformation [20,21]. This significantly transforms the inner structure of ceramics forming additional defect-related free volumes [22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Evolution of Free Volumes in Polycrystalline BaGa2O4 Ceramics Doped with Eu3+ Ions

et al. 2021

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BaGa2O4 ceramics doped with Eu3+ ions (1, 3 and 4 mol.%) were obtained by solid-phase sintering. The phase composition and microstructural features of ceramics were investigated using X-ray diffraction and scanning electron microscopy in comparison with energy-dispersive methods. Here, it is shown that undoped and Eu3+-doped BaGa2O4 ceramics are characterized by a developed structure of grains, grain boundaries and pores. Additional phases are mainly localized near grain boundaries creating additional defects. The evolution of defect-related extended free volumes in BaGa2O4 ceramics due to the increase in the content of Eu3+ ions was studied using the positron annihilation lifetime spectroscopy technique. It is established that the increase in the number of Eu3+ ions in the basic BaGa2O4 matrix leads to the agglomeration of free-volume defects with their subsequent fragmentation. The presence of Eu3+ ions results in the expansion of nanosized pores and an increase in their number with their future fragmentation.

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Study on the optical spectra of MgAl₂O₄ with oxygen vacancies

Cited by 11 publications

References 40 publications

Charge carrier trapping processes in un-doped and BaAl₂O₄:Eu³⁺ nanophosphor for thermoluminescent dosimeter applications

Charge carrier trapping processes in un-doped and BaAl₂O₄:Eu³⁺ nanophosphor for thermoluminescent dosimeter applications

Defect induced emission of MgAl₂O₄ sintered at high temperature

Evolution of Free Volumes in Polycrystalline BaGa2O4 Ceramics Doped with Eu3+ Ions

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Study on the optical spectra of MgAl2O4 with oxygen vacancies

Cited by 11 publications

References 40 publications

Charge carrier trapping processes in un-doped and BaAl2O4:Eu3+ nanophosphor for thermoluminescent dosimeter applications

Charge carrier trapping processes in un-doped and BaAl2O4:Eu3+ nanophosphor for thermoluminescent dosimeter applications

Defect induced emission of MgAl2O4 sintered at high temperature

Evolution of Free Volumes in Polycrystalline BaGa2O4 Ceramics Doped with Eu3+ Ions

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Study on the optical spectra of MgAl₂O₄ with oxygen vacancies

Charge carrier trapping processes in un-doped and BaAl₂O₄:Eu³⁺ nanophosphor for thermoluminescent dosimeter applications

Charge carrier trapping processes in un-doped and BaAl₂O₄:Eu³⁺ nanophosphor for thermoluminescent dosimeter applications

Defect induced emission of MgAl₂O₄ sintered at high temperature