Coarsening, coalescence and sintering of hexagonal ZnO elongated nanoparticles

Liu, I-Hsien; Shen, Pouyan

doi:10.1016/j.ceramint.2009.12.022

Cited by 6 publications

(7 citation statements)

References 14 publications

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“…This analysis results in a surface diffusion activation energy of Q A = 105 kJ mol −1 determined from the slope of linear fit over the temperature range of 300 – 600 °C. This value is close, but somewhat larger, to the activation energy of surface diffusion reported by others for nanocrystalline ZnO systems, [ 41 ] and the difference between values may be due to our larger ZnO crystallite sizes.…”

Section: Resultssupporting

confidence: 82%

“…This value is even lower than the activation energy of 55 and 209 kJ mol −1 reported by others on smaller ZnO nanocrystalline grains, assuming m = 3 – 3.5. [ 41,55 ] Such low activation energy for grain growth was also observed by Kim et al. on substrate constrained Y 2 O 3 doped zirconia thin films and is attributed to the constrained structure with large, isolated pores.…”

Section: Resultssupporting

confidence: 56%

“…Interparticle necks form without appreciable densification and are attributed to surface diffusion, similar to other studies. [ 39,41,42 ] After extending the hold time to 24 h, rods had merged at their junctions as observed from top‐views and side‐views, and individual rods are no longer distinguishable in cross‐sectional views (see Figure 1i–k). This morphological change reflects a significant surface reduction as necks grow pervasively.…”

Section: Resultsmentioning

confidence: 99%

“…At the early stage of sintering, the increasing pore size is consistent with the coalescence of cylindrical pores among ZnO nanorods as observed by Liu and coworkers. [ 41 ]…”

Section: Resultsmentioning

confidence: 99%

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Investigating the Trade‐off between Optical and Mechanical Properties during Constrained Sintering of Mesomorphic Ceramic Films

Cheng

Zhang

Chen

et al. 2023

Advanced Optical Materials

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Robust, transparent, and birefringent inorganic films are demanded for polarization control of high‐power lasers. While single crystals or films obtained via glancing angle deposition exhibit desirable optical properties and laser damage resistance, these methods are limited by cost and scalability. Mesomorphic ceramics as inorganic solids with liquid crystalline superstructure offer appealing transparency and birefringence but lack mechanical robustness due to their high porosity. Here, the effect of sintering on optical and mechanical properties of mesomorphic ceramics is evaluated. Films prepared by blade coating are sintered under varying conditions. Constrained sintering accomplished crystallite growth, densification, and morphological changes including necking as well as cracking while preserving the crystallographic orientation. The extent of sintering as a function of thermal treatment is quantified by morphology, surface area loss, and crystallite growth. Moreover, activation energies for surface diffusion and grain growth are estimated by surface area analysis and X‐ray diffraction peak narrowing, respectively. After sintering, birefringence decreases while Young's modulus and hardness improve as the film densifies. Upon partial sintering, mesomorphic ceramics retain transparency, high birefringence, and enhanced modulus. Laser‐induced damage threshold is measured as well. The reported results represent an important step toward the assembly and sintering of robust waveplates with high laser damage resistance.

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Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 56%

Section: Resultsmentioning

confidence: 99%

“…At the early stage of sintering, the increasing pore size is consistent with the coalescence of cylindrical pores among ZnO nanorods as observed by Liu and coworkers. [ 41 ]…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Investigating the Trade‐off between Optical and Mechanical Properties during Constrained Sintering of Mesomorphic Ceramic Films

Cheng

Zhang

Chen

et al. 2023

Advanced Optical Materials

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“…This thin film apparently consists of nanocrystalline ZnO grains, which are of about 50–100 nm in size with an elongated shape. This behavior is related to the capability of the NPs to coalescence in surfaces . Since the melting point for bulk ZnO is 1500 °C, this reactivity of the ZnO NP seeds at 900 °C reveals a different behavior at the nanoscale by the melting point depression.…”

Section: Resultsmentioning

confidence: 99%

Raman and photoluminescence properties of ZnO nanowires grown by a catalyst‐free vapor‐transport process using ZnO nanoparticle seeds

Güell

Martínez‐Alanis

Khachadorian

et al. 2016

Physica Status Solidi (b)

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We report the synthesis of ZnO nanowires by a catalyst-free vapor-transport process on SiO 2 /Si substrates. A modification of the method was performed using small ZnO nanoparticles ($5 nm) in low concentration suspensions. The use of dichloromethane or toluene in the suspensions influences the nanoparticle distribution over the surface. The obtained nanowires have diameters ranging from 20 to 100 nm and lengths from 0.5 to 1 mm. Raman scattering results show a narrow ($7 cm À1 ) full width at half maximum of the E 2 high optical phonon mode, which demonstrate a good-crystal quality of the ZnO nanowires obtained. Room temperature photoluminescence measurements show a broad emission band in the visible range at 430-830 nm, which is attributed to intrinsic defects. A notable decrease of this visible band was achieved making this method suitable for almost defect-free ZnO nanowires. The photoluminescence results at 5 K demonstrate the role of surface defects as responsible for the visible band.

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Dependence of the textural properties and surface species of ZnO photocatalytic materials on the type of precipitating agent used in the hydrothermal synthesis

et al. 2017

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Three different precipitating agents (NaOH, NH 4 (H)CO 3 and CO(NH 2) 2) have been applied for the hydrothermal synthesis of ZnO powder materials, aiming at obtaining various types of porosity and surface species on ZnO. The synthesis procedures were carried out in the presence and in the absence of tri-block copolymer Pluronic (P123, EO20PO70EO20). These materials were characterized by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDX), BET method and TG-differential thermal analysis (DTA) method, and their photocatalytic activities were tested in the removal azo dye Reactive Black 5 (RB5). The urea precipitant yields spongy-like surface forms and the greatest share of mesopores. It has the highest specific surface area, highest degree of crystallinity of wurtzite ZnO phase and largest content of surface OH groups in comparison with the other two precipitants. The zinc hydroxycarbonate intermediate phase is missing in the case of NaOH as precipitating agent; therefore, it manifests poorer textural characteristics. The morphology of P123-modified sample is different and consists of needle-shaped particles. The urea-precipitated samples display superior performance in the photocatalytic oxidation reaction, compared with the other precipitated samples. The other two precipitating agents are inferior in regard to their photocatalytic activity due to greater share of micropores (not well-illuminated inner surface) and different surface morphologies.

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Coarsening, coalescence and sintering of hexagonal ZnO elongated nanoparticles

Cited by 6 publications

References 14 publications

Investigating the Trade‐off between Optical and Mechanical Properties during Constrained Sintering of Mesomorphic Ceramic Films

Investigating the Trade‐off between Optical and Mechanical Properties during Constrained Sintering of Mesomorphic Ceramic Films

Raman and photoluminescence properties of ZnO nanowires grown by a catalyst‐free vapor‐transport process using ZnO nanoparticle seeds

Dependence of the textural properties and surface species of ZnO photocatalytic materials on the type of precipitating agent used in the hydrothermal synthesis

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