Some physical properties of ZnAl2O4: Cr3+(Co2+) powders prepared by hydrothermal method

Hà, Lê Thị Thu; Lanh, Phung Thi; Long, Nguyen Ngoc; Loan, Trinh Thi

doi:10.1088/1742-6596/187/1/012053

Cited by 12 publications

(7 citation statements)

References 11 publications

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“…7 (b), the E g were measured with the help of reflectance spectra plotting graphs of (K x hν) n versus (hv) (with n = 2, which is appropriate for a direct band gap material such as ZnAl 2 O 4 ). The extrapolation of linear region of this plot to (K x hν) 2 = 0…”

Section: Reflectance and Band Gap Analysis (Uv-vis Spectroscopy)mentioning

confidence: 99%

“…Over the past decades, spinel compounds have attracted interest in many researchers around the globe due to their properties such as high chemical and thermal stability, high mechanical resistance, low sintering temperature and high quantum yields [1,2]. Spinels are class of binary transition metal oxides of the form AB 2 O 4 with varied structures and owing to their unique properties, they have found potential applications in the area of material science and technology [3,4].…”

Section: Introductionmentioning

confidence: 99%

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Effects of annealing time on the structure and optical properties of ZnAl2O4/ZnO prepared via citrate sol-gel process

Motloung

Kumari

Koao

et al. 2018

Materials Today Communications

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ZnAl 2 O 4 nano-powders have been successfully prepared via citrate sol-gel technique. All powder samples were annealed at 600 o C for 1, 2, and 3 h. Thermogravimetric analysis (TGA) confirmed that the minimum annealing temperature of crystallization is ~ 400 °C. Fourier Transform Infrared (FTIR) results showed a series of absorption peaks in the range of 810-4000 cm-1. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) results showed that the prepared nano-crystals consists of the mixture of both cubic (ZnAl 2 O 4) and hexagonal (ZnO) structures. Ultra violet visible (UV-vis) spectroscopy revealed that the annealing time (AT) influences the band gap of the prepared phosphor materials. When the 2 samples were excited at 275 nm, two emission peaks at 428 nm (violet) and 561 nm (green-yellow) were observed and they are attributed to the defects levels within the ZnO and ZnAl 2 O 4 band gaps. The Commission Internationale de l'Elcairage (CIE) colour coordinates confirmed that all the prepared samples exhibit the violet emission and varying the AT does not influence the emission colour.

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Section: Reflectance and Band Gap Analysis (Uv-vis Spectroscopy)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of annealing time on the structure and optical properties of ZnAl2O4/ZnO prepared via citrate sol-gel process

Motloung

Kumari

Koao

et al. 2018

Materials Today Communications

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“…Fluorescence is the term used to describe a substance’s spontaneous light emission when it is exposed to stimulating electromagnetic radiation. Phosphorescence refers to a material’s ability to absorb light and delay its immediate reemission. − The emission intensity (efficiency) of the phosphor will be low if the concentration of an activator ion exceeds a specific value. The increased delocalization of the excitation or cross relaxation (exchange contact) between luminous centers, which is known as the concentration quenching effect, is the cause of this phenomenon .…”

Section: Fundamentalsmentioning

confidence: 99%

Synthesis and Luminescence Characterization of Downconversion and Downshifting Phosphor for Efficiency Enhancement of Solar Cells: Perspectives and Challenges

Satpute

Mehare

Tiwari

et al. 2022

ACS Appl. Electron. Mater.

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Currently, the world is facing an energy crisis. One of the techniques to fulfill the energy demand is to increase the utilization of solar energy. For harvesting solar energy in large amounts, it is essential to develop efficient solar cells. Notably, solar cells (photovoltaic cells) produce electricity from solar energy. The biggest hurdles, however, are the capability and reliability of solar cells. Poor energy density and the spectrum in the bandgap of semiconductor phosphors do not match the energy allocation of the photons in solar spectra lines. These issues and cell efficacy must be addressed before photovoltaic cells can be developed as a viable source of electrical power. The amount of energy generated per unit area depends linearly on cell efficiency. Hence, it makes sense to increase the efficiency rather than enhancing the space for solar cell installation. One well-known method for converting a high-energy photon into two or more lower-energy photons is “downconversion”, which makes use of the wide solar spectrum required for solar cells. The design maximizes the use of the entire sunlight spectrum, improving the efficiency of various solar cell types. This review article surveys how spectrum converters, especially lanthanide-based downconverters and downshifters will be developed. This review focuses on the current materials and methods used to enable the downconversion and downshifting processes in solar cells and some of the challenges in developing solar cells.

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“…[1][2][3][4] Spinel as a kind of nanomaterials is an ideal host lattice for transition metal and rare earth ions to generate luminescence, on account of its facecentered cubic (FCC) structure. [5][6][7][8] ZnAl 2 O 4 with typical spinel structure has been used as a phosphor host material doped with various metal and rare earth ions in previous literatures. 7 8 And with the properties of excellent chemical and optical stability, high mechanical resistance, low sintering temperature and high quantum yield, ZnAl 2 O 4 spinel can be used as host material of optical coating, thin film electroluminescence displays, stress imaging device, etc.…”

Section: Introductionmentioning

confidence: 99%

“…[5][6][7][8] ZnAl 2 O 4 with typical spinel structure has been used as a phosphor host material doped with various metal and rare earth ions in previous literatures. 7 8 And with the properties of excellent chemical and optical stability, high mechanical resistance, low sintering temperature and high quantum yield, ZnAl 2 O 4 spinel can be used as host material of optical coating, thin film electroluminescence displays, stress imaging device, etc. 9 10 Meanwhile, Nd 3+ -doped inorganic nanomaterials also have been widely studied because of their unique near infrared (NIR) emission, which have significant applications in biological and optical fields.…”

Section: Introductionmentioning

confidence: 99%

Electrospun Nd3+-doped spinel nanoparticles/nanofibers with both excitation and emission wavelengths in the optical window of cells and tissues

Yang¹,

Zhao²,

Pan³

et al. 2013

Mat Express

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ZnAl 2 O 4 nanofibers and nanoparticles were in situ synthesized by electrospinning technique. Utilizing poly (vinyl pyrrolidone) (PVP) with different degree of polymerization, SEM (scanning electron microscope) results indicate that ZnAl 2 O 4 nanostructures exhibit different morphologies under the same electrospun parameters. When PVP with high molecular weight (Mw = 1,300,000) was used, the ultra-long ZnAl 2 O 4 nanofibers were obtained with an average diameter of ∼200 nm. However, while PVP with low molecular weight (K-30) was used, the ZnAl 2 O 4 changed into particle-shape with an average size of ∼100 nm. Utilizing Nd 3+ ions as the optical activator, three emission peaks centered at 905 nm, 1064 nm and 1335 nm were detected respectively in the photoluminescence (PL) spectra of ZnAl 2 O 4 :Nd 3+ nanostructures under 808 nm laser excitation. It is noticed that both the excitation wavelength (808 nm) and the emission wavelength (905 nm and 1064 nm) are located in the 700-1100 nm optical window of cells and tissues. And the cytotoxicity investigation indicates ZnAl 2 O 4 :Nd 3+ nanostructures are biocompatible with human cells, which endow their potential application as biological markers, etc.

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Some physical properties of ZnAl₂O₄: Cr³⁺(Co²⁺) powders prepared by hydrothermal method

Cited by 12 publications

References 11 publications

Effects of annealing time on the structure and optical properties of ZnAl2O4/ZnO prepared via citrate sol-gel process

Effects of annealing time on the structure and optical properties of ZnAl2O4/ZnO prepared via citrate sol-gel process

Synthesis and Luminescence Characterization of Downconversion and Downshifting Phosphor for Efficiency Enhancement of Solar Cells: Perspectives and Challenges

Electrospun Nd<SUP>3+</SUP>-doped spinel nanoparticles/nanofibers with both excitation and emission wavelengths in the optical window of cells and tissues

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