A new approach to producing transparent ZnAl 2 O 4 ceramics

Belyaev, Alexander; Evdokimov, I.I.; Дроботенко, В. В.; Sorokin, A. A.

doi:10.1016/j.jeurceramsoc.2017.02.041

Cited by 31 publications

(18 citation statements)

References 16 publications

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“…[10][11][12] Fully dense ZnAl 2 O 4 ceramics have been reported in the literature, however, the grain sizes were relatively large. For example, Belyaeva et al 13 fabricated ZnAl 2 O 4 ceramics with an average grain size of 33 μm by using hot pressing and using ZnF 2 as a sintering aid. The samples were highly transparent, with light transmittance measured at 63% with a 550 nm wavelength.…”

Section: Introductionmentioning

confidence: 99%

Grain boundary strengthening in nanocrystalline zinc aluminate

2019

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Fully dense transparent zinc aluminate ceramics with nanoscaled grain sizes were fabricated by Deformable Punch Spark Plasma Sintering (DP‐SPS). Optical transmission spectra showed high transparency, with up to 70% transmitted light in the visible spectrum. Vickers hardness was measured and grain boundary strengthening observed, showing hardness increase from 18.2 GPa up to 22.5 GPa as the grain sizes decreased from 60.3 to 10.1 nm. The trend followed the Hall‐Petch relationship, with hardness linearly proportional to the inverse of square root of grain size. A low grain size limit reported in previous literature below which hardness decreases, known as inverse Hall‐Petch relationship, was not observed within the studied grain size range. Cross‐sections of the hardness tests' indentations were prepared by focused ion beam and observed by electron microscopy and showed radically different crack patterns underneath the indentation imprint when contrasting samples with dissimilar grain sizes, shedding light on the mechanisms behind the observed grain boundary hardening mechanisms.

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Section: Introductionmentioning

confidence: 99%

Grain boundary strengthening in nanocrystalline zinc aluminate

2019

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“…The valence band maximum (VBM) and conduction band minimum (CBM) for ZnAl 2 O 4 are located at the Γ point; therefore, the calculated direct band‐gap is 6.19 eV (Figure 4a). This value is only 0.14 eV (2.3%) greater than the experimental value (6.05 eV), [ 103 ] whereas ZnGa 2 O 4 and ZnIn 2 O 4 have an indirect ( L‐Γ ) band‐gap of 4.68 and 3.61 eV, respectively (see Figure 4B,C). The experimental band‐gap for ZnGa 2 O 4 is about 4.62 eV.…”

Section: Resultsmentioning

confidence: 64%

“…[ 68 ] Furthermore, a DFT/LDA calculation for the ZnAl 2 O 4 normal spinel was reported with a Γ‐Γ direct band‐gap of 4.25 eV. These results underestimate the experimental band‐gap energy by 36.03% for ZnAl 2 O 4 (experimental band‐gap 6.05 eV [ 103 ] ) and 48.26% for ZnGa 2 O 4 (experimental bang‐gap 4.62 eV [ 5 ] ). However, for the ZnGa 2 O 4 and ZnIn 2 O 4 materials simulated by the DFT/LDA approach, the band‐gap results were cited as indirect band‐gaps at Γ‐ K direction with 2.82 and 1.71 eV.…”

Section: Resultsmentioning

confidence: 99%

Quantum mechanical modeling of Zn‐based spinel oxides: Assessing the structural, vibrational, and electronic properties

Oliveira

Ribeiro

Longo

et al. 2020

Int J of Quantum Chemistry

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The structural, electronic, and vibrational properties of two leading representatives of the Zn-based spinel oxides class, normal ZnX 2 O 4 (X = Al, Ga, In) and inverse Zn 2 MO 4 (M = Si, Ge, Sn) crystals, were investigated. In particular, density functional theory (DFT) was combined with different exchange-correlation functionals: B3LYP, HSE06, PBE0, and PBESol. Our calculations showed good agreement with the available experimental data, showing a mean percentage error close to 3% for structural parameters. For the electronic structure, the obtained HSE06 band-gap values overcome previous theoretical results, exhibiting a mean percentage error smaller than 10.0%. In particular, the vibrational properties identify the significant differences between normal and inverse spinel configurations, offering compelling evidence of a structure-property relationship for the investigated materials. Therefore, the combined results confirm that the range-separated HSE06 hybrid functional performs the best in spinel oxides. Despite some points that cannot be directly compared to experimental results, we expect that future experimental work can confirm our predictions, thus opening a new avenue for understanding the structural, electronic, and vibrational properties in spinel oxides.

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“…[35][36][37][38] However, most transparent oxide ceramics are generally prepared from raw nanopowders or/and cubic crystalline powders through different sintering techniques (vacuum sintering, spark plasma sintering, hot uniaxial sintering). [34,39,40] Numerous studies report transparent spinel ceramics such as MgAl 2 O 4 [33,41,42] or ZnAl 2 O 4 [43][44][45][46][47][48] while the zinc gallate spinel has not been yet achieved as a transparent ceramic. Indeed, the difference of evaporation speed of ZnO and Ga 2 O 3 (i.e.…”

Section: Introductionmentioning

confidence: 99%

First ZnGa2O4 transparent ceramics

Mével¹,

Carreaud²,

Delaizir³

et al. 2021

Journal of the European Ceramic Society

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A new approach to producing transparent ZnAl 2 O 4 ceramics

Cited by 31 publications

References 16 publications

Grain boundary strengthening in nanocrystalline zinc aluminate

Grain boundary strengthening in nanocrystalline zinc aluminate

Quantum mechanical modeling of Zn‐based spinel oxides: Assessing the structural, vibrational, and electronic properties

First ZnGa2O4 transparent ceramics

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