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Microstructural characterization of nanostructured Al2O3-ZrO2 eutectic layer by laser rapid solidification method
摘要： In the present work, nanostructured surface layers of Al2O3-ZrO2 eutectic with a thickness of approximate 1000 μm and free of cracks and pores were produced on the surface of conventionally-sintered Al2O3-ZrO2 ceramic via the laser irradiation rapid solidification process. The molten pool geometry and microstructure were characterized by scanning electron microscopy and Raman spectroscopy. The geometrical evolution of molten pool in response to laser power and laser scanning velocity was established, where the top view of molten pool exhibits a circular shape at low velocities and gradually evolves into an oval-shaped surface at high velocities. Singular Al2O3-ZrO2 eutectic colonies with a size of 100-200 μm, which is formed around a spontaneously nucleated dendritic ZrO2 core, are found on the surface of laser-remelted layer. The eutectic colony has an interphase spacing of 190-280 nm. The variation of eutectic spacing with growth rate is essentially linear on the logarithmic scale as λ=KV-0.4 by binary regression analysis. Predicted by the Jackson-Hunt theory on eutectic solidification (JH theory), the eutectic spacing is consistent with the inverse-square-root dependence on growth rate with a proportionality constant of 3.32. The eutectic colonies consist of α-Al2O3, t-ZrO2 and m-ZrO2 phases, where α-Al2O3 and t-ZrO2 are the dominant phases and the m-ZrO2 phase increases with the decrease of laser scanning velocity.
关键词： Al2O3-ZrO2,Nanoeutectic layer,Laser remelting,Surface nanostructuring
更新于2025-11-28 14:24:20
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Photodegradation of thiophene over ZrO2–SiO2 nanoparticles: impact of copper decoration on their photocatalytic activity
摘要： A sol–gel technique was useful for the synthesis of zirconia–silica nanoparticles. Metallic copper has decorated zirconia–silica nanoparticles via photo-assisted deposition method, decorated copper mass percent was varied from 0.5, 1.0, 1.5, and 2.0 wt%. XRD results confirm that decoration of zirconia–silica nanoparticles by copper did not alert XRD pattern of zirconia–silica nanoparticles and there are no peaks for copper or copper oxide, due to high dispersion of copper above a surface of zirconia–silica nanoparticles. The decoration of zirconia–silica nanoparticles by copper was reduced band gap energy of zirconia–silica nanoparticles from 3.20 to 2.35 eV with 1.5 wt% Cu decoration. Photocatalytic oxidation of thiophene in presence of visible light was selected to measure the impact of metallic copper on photocatalytic activity of zirconia–silica nanoparticles. 1.5 wt% Cu-decorated zirconia–silica nanoparticles can degrade 100% of thiophene within 90 min.
关键词： ZrO2–SiO2,Sol–gel,Thiophene degradation,Cu decoration,Enhanced photocatalysis,Visible light
更新于2025-11-14 15:26:12
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Structural and photocatalytic properties of co-doped hybrid ZrO2–TiO2 photocatalysts
摘要： In this study, pure TiO2, ZrO2, and hybrid ZrO2–TiO2 photocatalysts were synthesized through solgel process and calcined at three different temperatures. The synthesized photocatalysts were characterized using powder X-ray diffraction (PXRD), field-emission scanning electron microscopy (FESEM), Brunauer–Emmet–Teller (BET), ultraviolet–visible (UV–Vis) spectrometer, and photoluminescence (PL) spectrometer. The PXRD patterns show that the rutile phase of TiO2 was suppressed through co-doping with ZrO2 and produced small crystallite size. The hybrid photocatalysts with small crystallite size recorded the highest surface area of 114.7 m2/g compared to pure TiO2 and ZrO2 photocatalysts as confirmed by BET analysis. Irregular size and shape was observed in the hybrid photocatalysts compared to spherical shape and size in TiO2 and flaky shape in ZrO2 as shown by the FESEM images. The optical properties of the photocatalysts investigated using UV–Vis spectroscopy showed a decrease in band gap energy of pure TiO2 through linear extrapolation from the Tauc’s plot despite the slightly higher band gap energy of the hybrid photocatalysts. However, PL analysis showed that doping of ZrO2 into TiO2 increased the separation efficiency of the electron–hole pairs and enhanced the photocatalytic activity. The phenol degradation of the hybrid ZrO2–TiO2 photocatalysts was higher compared to those of the pure TiO2 and ZrO2.
关键词： Hybrid TiO2–ZrO2 photocatalysts,Solgel,Phenol degradation
更新于2025-11-14 15:25:21
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Investigation of Electrical Characteristics on LaAlO <sub/>3</sub> /ZrO <sub/>2</sub> /IGZO TFTs with Microwave Annealing
摘要： Conventional thin film transistor suffered from high threshold voltage, poor subthreshold swing, and high operation voltage. These shortcomings make the traditional thin film transistor does not meet the needs with the high-performance, high-resolution, low temperature and energy conservation nowadays. Due to the good selectivity of energy transformation and rapid heating rate, microwave annealing is promising to replace conventional furnace annealing and applied in the investigation. LaAlO3/ZrO2 is employed as gate electrode and gate dielectric layer for a-IGZO TFTs, under the premise that performance of a-IGZO TFTs without decreasing. With adjusting the power/time of microwave annealing, the effect on electrical characteristics of a-IGZO TFTs is investigated.
关键词： ZrO2,Microwave Annealing,a-IGZO TFTs,LaAlO3
更新于2025-09-23 15:23:52
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Synthesis and characterization of composites ZnZr for the photocatalytic degradation of phenolic molecules. Addition effect of ZrO <sub/>2</sub> over hydrozincite Zn <sub/>5</sub> (OH) <sub/>6</sub> (CO <sub/>3</sub> ) <sub/>2</sub>
摘要： BACKGROUND: Composite materials ZrO2/Zn5(OH)6(CO3)2 were prepared in only one step by chemical coprecipitation and thermal hydrolysis of urea. ZrO2 was added at 5, 8 and 10 mol%. The samples were dried at 80°C and characterized by adsorption-desorption of N2 isotherms, XRD, SEM, techniques and DRS, UV-Vis, FTIR and XPS spectroscopies. The materials were assessed in the photodegradation of phenol and polychlorinated phenolic molecules under UV-light irradiation. The possible mechanism was discussed from studies that corroborated o discarded the formation of the species ?OH, ?O2- and h+. RESULTS: The addition of ZrO2 to Zn5(OH)6(CO3)2 resulted in a composite material with high photoactivity. Being the most efficient the sample with 8 mol% of ZrO2. The photodegradation enhancement was partly achieved by an increment in the specific surface area and principally due to localized states originated in the composite interphase which improve the charges transfer. It was found by XPS study that the ZrO2 addition increment the oxygen vacancies which enhance the organic molecule photodegradation via direct holes attack. CONCLUSION: The composite system ZnZr can be an excellent alternative for the persistent organic pollutants photodegradation due to the low cost, high stability and null toxicity of the support Zn5(OH)6(CO3)2.
关键词： ZrO2,hydrozincite,phenol-chlorophenols photodegradation,composites
更新于2025-09-23 15:23:52
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Amorphous silicon and silicates-stabilized ZrO2 hollow fiber with low thermal conductivity and high phase stability derived from a cogon template
摘要： ZrO2 ?bers are used as refractory materials owing to their excellent thermal resistance and thermal stability. Natural cogon ?ber is a type of hollow Gramineae ?ber, and usually contains a small amount of amorphous silicon and silicates, such as SiO2, MgSiO3, CaSiO4, and Al2SiO5, which can e?ectively avoid the phase transition of ZrO2. In this study, hollow ZrO2 ?bers with remarkable thermal insulation and phase stability were synthesized using a cogon ?ber template. The results showed that the ?nal ZrO2 ?bers successfully inherited the hollow structure and amorphous substance from the cogon template. The hollow structure of the biomorphic ZrO2 ?ber helped prevent heat ?ow more e?ciently compared to solid ?bers and reduced the thermal conductivity to a signi?cant extent. In addition, the amorphous silicon and silicates played an important role in the phase stability of tetragonal ZrO2; the transformation from the tetragonal to monoclinic phase was avoided at room temperature and in humid environment.
关键词： Thermal conductivity,Amorphous silicon and silicates,Cogon ?bers,Phase stability,ZrO2 hollow ?bers
更新于2025-09-23 15:23:52
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AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2017 (ISCPMS2017) - Bali, Indonesia (26–27 July 2017)] - Novel Ag2O/ZrO2 composites with enhanced photocatalytic water decontamination
摘要： In this study Silver Oxide/Zirconium Dioxide (Ag2O/ZrO2) with different Ag2O:ZrO2 weight ratio were synthesized using microwave assisted method for remove organic pollutant from the aqueous solution through photocatalytic performance. The structural properties of the samples characterized by X-ray diffraction confirm the existence of cubic structures from silver (Ag) nanoparticles, cubic structure silver oxide (Ag2O), and tetragonal structures from Zirconia (ZrO2). The higher ZrO2 loading resulted in the higher Ag nanoparticles on the samples. The thermal analysis was investigated using Differential Thermal Analysis and Thermogravimetric Analysis (DTA/TGA). The weight lost at 400 °C could be attributed to the phase transformation from Ag2O into Silver nanoparticles followed by accepted heat from the environment. The UV vis absorbance spectra confirm the existence of surface plasmon resonance from silver nanoparticles. The photocatalytic activity was tested on the degradation of methylene blue from the aqueous solution. As can be seen from the figure that the higher ZrO2 loading resulted in the higher photocatalytic activity under visible light irradiation with percentage degradation approximately 83 % The enhancement of photocatalytic performance due to the retarding recombination electron and holes.
关键词： ZrO2,Ag2O,photocatalytic
更新于2025-09-23 15:23:52
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Crystallization kinetics and thermal stability of ZrO <sub/>2</sub> monolithic aerogel improved by SiO <sub/>2</sub> layer
摘要： ZrO2 aerogel modified by SiO2 (ZSA) was synthesized by aging ZrO2 gel in tetraethoxysilane (TEOS) solution using ZrOCl2·8H2O as precursor, and 1,2-propylene oxide (PO) as gelation agent followed by ethanol supercritical fluid drying. Crystallization kinetics and thermal stability of ZSA while calcined at elevated temperature were studied comparing with pure ZrO2 aerogel. The prepared samples were characterized using TG-DSC, N2 adsorption/desorption, SEM and TEM. The results show that thermal stability of ZSA are highly improved due to the SiO2 layer hindering the proliferation, nucleation and growth process of ZrO2.
关键词： ZrO2,thermal stability,aerogel,SiO2,crystallization kinetics
更新于2025-09-23 15:23:52
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Synthesis and Characterization of ZnO-ZrO <sub/>2</sub> Nanocomposites for Photocatalytic Degradation and Mineralization of Phenol
摘要： ZnO-ZrO2 nanocomposites using zinc (II) acetylacetonate and different ZnO contents (13, 25, 50, and 75% mol) were synthesized through sol-gel method. The synthesis process was strongly related to nanocomposite properties especially on their structural composition. The obtained ZnO-ZrO2 nanomaterials presented tetragonal crystalline structure for zirconia whereas hexagonal one was formed in ZnO. Raman spectroscopy and XRD patterns confirmed the formation of tetragonal zirconia whereas inhibition of monoclinic structure was observed. Addition of ZnO affected the pore size distribution of the composite, and the measured specific surface areas were from 10 m2/g (for pure ZnO) to 46 m2/g (pristine ZrO2). Eg values of ZrO2 were modified by ZnO addition, since calculated values using Kubelka-Munk's function varied from 4.73 to 3.76 eV. The morphology and size of the nanomaterials investigated by electron microscopy showed formation of nanorods for ZnO with sizes ranging from 50 nm to 300 nm while zirconia was formed by smaller particles (less than 50 nm). The main advantage of using the nanocomposite for photocatalytic degradation of phenol was the mineralization degree, since 75ZnO-ZrO2 nanocomposite surpassed mineralization reached by pure ZnO and also inhibited formation of undesirable intermediates.
关键词： sol-gel method,UV-A irradiation,phenol mineralization,photocatalytic degradation,ZnO-ZrO2 nanocomposites
更新于2025-09-23 15:22:29
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In-Situ Measurement of Outgassing Generated from EUV Metal Oxide Nanoparticles Resist During Electron Irradiation
摘要： In this study, we prepared the EUV metal resist, which included ZrO2 nano-particle and three type ligands as 2-methyl-2-propenoic acid (MAA), 2-methylpropanoic acid (IBA) and vinylbenzoic acid (VBA). Each resist was prepared by blending each material separately for evaluating the outgassing from EUV resist materials. We prepared three-type samples of ZrO2-MAA, ZrO2-IBA and ZrO2-VBA by coating each resist, and evaluated the outgassing from these samples during irradiation of 2 keV electron by in-situ mass spectrometry. From the results of mass spectrum, we could observe the outgassing of PAG as unique peaks. And each ligand peak was distributed over the low mass range. On the other hand, the ZrO2 peaks could not be observe in mass spectrum of each sample. Thus, we guess that ZrO2 nano-particles might not be evaporating during 2 keV electron irradiation.
关键词： Ligand,EUV metal resist,Electron irradiation,Mass spectrometry,In-situ outgas measurement,ZrO2
更新于2025-09-23 15:22:29