Preparation Principle and Crystal Growth Kinetics of Loaded Nanocrystal TiO2

Zhao, Ying Na; Zhang, Wen Li

doi:10.4028/www.scientific.net/AMR.194-196.585

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Home Advanced Materials Research Advanced Engineering MaterialsPreparation Principle and Crystal Growth Kinetics...

Preparation Principle and Crystal Growth Kinetics of Loaded Nanocrystal TiO₂

Abstract:

Nanocrystal TiO₂ photocatalystic materials were prepared by melt-phase separation technique, and its preparation principle was discussed in this paper. Anatase nanometer TiO₂ could be obtained by heat-treatment at 550 °C for 10 min, which is well combined with porous glass carrier and the particles size is about 25 nm. The growth kinetics of TiO2 crystalline analysis results showed that the growth activation energy Q1 was about 63.27 KJ/mol (<600 °C), and Q2 was about 22.78 KJ/mol (>600 °C).TiO₂ crystalline growth closely related to glass phase separation. TiO₂ particles grew quickly with the glass phase separation size increase, and then the particles growth rate became slow because of being limited by glass phase separation structure.

Info:

Periodical:

Advanced Materials Research (Volumes 194-196)

Main Theme:

Advanced Engineering Materials

Edited by:

Jianmin Zeng, Taosen Li, Shaojian Ma, Zhengyi Jiang and Daoguo Yang

Pages:

585-588

DOI:

https://doi.org/10.4028/www.scientific.net/AMR.194-196.585

Citation:

Y. N. Zhao and W. L. Zhang, "Preparation Principle and Crystal Growth Kinetics of Loaded Nanocrystal TiO₂", Advanced Materials Research, Vols. 194-196, pp. 585-588, 2011

Online since:

February 2011

Authors:

Ying Na Zhao, Wen Li Zhang

Keywords:

Growth Kinetic, Melt-Phase Separation, Nanocrystal TiO₂

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References

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Paper TitlePages

Quantitative Evaluation of the Glass Forming Ability of (Cu-Zr) Based Glass Alloys with Thermodynamics Method

Authors: Hui Qiang Li, Long Fei Liu

Abstract: Along nucleation → crystalline growth →crystalline fraction → critical cooling rate, the relationship between the nucleation, elements, cooling rate and the Glass Forming Ability of (Cu-Zr) based glass alloys is quantitatively studied with thermodynamics method, and a better method to evaluate the critical cooling rate of glass alloys is also proposed in this paper. The computed results show that: (1) with the increase of element number, the steady state nucleation rate drops gradually. From Cu-Zr, Cu-Zr-Al, Cu-Zr-Al-Ni, to Cu-Zr-Al-Ni-Ti, the peak value of nucleation rate decreases from 10²¹ mol^-1s^-1 to 10¹³ mol^-1s^-1. It is also found the nucleation rate both drops with the substitution of Ni with Cu or Al with Zr; (2) with the increase of cooling rate, the nucleation rate drops sharply. When the cooling rate reaches 10³K/s, the nucleation rates of Cu₆₄Zr₃₆, Cu₅₄Zr_42.5Al_3.5, Cu₅₅Zr₄₀Al₅ and Cu₃₀Zr₅₅Al₁₀Ni₅drop to 10⁹mol^-1s^-1, 10⁶mol^-1s^-1, 10⁷mol^-1s^-1 and 10³mol^-1s^-1 accordingly.

1622

Surface Morphology of P₂O₅-CaO-Nb₂O₅-Na₂O Glass-Ceramics after Acid Treatment: SEM and XRD Study

Authors: Agnese Stunda, Dmitrijs Jakovlevs, Lasma Poca, Liga Berzina-Cimdina

Abstract: Modification of surface morphology and composition of niobophosphate glass and glass-ceramic in the system P₂O₅-CaO-Nb₂O₅-Na₂O was investigated. Amorphous, partly crystalline and crystalline samples were prepared in shape of pellet with diameter 10 mm. Samples were treated in 1 and 5 days in citric acid at 37°C and 3h in boiling HCl. Surface morphology before and after treatment was investigated by scanning electron microscopy (SEM), phase composition by X-ray powder diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). Glass sample was smooth, after treatment in citric acid it had cracks and pit-holes on the surface. Partly crystalline sample was smooth and contained inclusions of crystalline Ca₃(PO₄)₂ and Ca₂P₂O₇. Platy crystals of Ca₃(PO₄)₂ dissolved first, than bulky Ca₂P₂O₇. Crystalline samples contained Na₄Nb₈P₄O₃₂ and calcium phosphate phases; surface was rough before and after treatment. EDX showed that amount of phosphorous is proportional to amount of calcium and inversely proportional to amount of sodium and niobium in glass-ceramic samples.

Preparation and Characterization of Fe₃₆Co₃₆B₂₀Si₄Nb₄ Nanocrystalline/Amorphous Matrix Composite

Authors: Gang Li, Zhan Zhe Zhang

Abstract: In this paper, we report a Fe-based nanocrystalline-amorphous matrix composite synthesised via partially crystallising an amorphous alloy. The microstructure of the composite was characterize. An amorphous rod of 2mm in diameter was initially prepared via injecting the melted Fe₃₆Co₃₆B₂₀Si₄Nb₄ alloy into a copper mould in vacuum, which was confirmed to be completely amorphous by X-ray difraction（XRD）. Differential scanning calorimeteric（DSC）curve shown that the span △Tx of the supercooled liquid region and the reduced glass transition temperature（Tg/Tm）for the amorphous alloy are 40 K and 0.615, respectively. The composite composed of nanocrystalline particles homogeneously dispersed in an amorphous matrix was prepared by isothermal annealing. In this course, the amorphous Fe-based sample was held for different time at different temperature. The types of the nanocrystalline phases obtained in different annealing conditions were characterised by XRD and selected-area diffraction pattern（SAED）.The crystallization behavior of the amorphous Fe-based alloy was discussed.

778

Effect of Concentration of Iron Oxide on Crystallization Behavior in Leadless Iron Oxide Crystalline Glaze

Authors: Supakorn Silakate, Anucha Wannagon, Apinon Nuntiya

Abstract: The objectives of this study were to prepare leadless crystalline glazes from iron oxide by using low temperature firing (1,100°C) and to study the effect of concentration of iron oxide on the phase composition of the glaze raw materials on phase transformation in leadless iron oxide crystalline glaze. The crystalline phases were investigated by using the DTA, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The composition of the glaze raw materials compose of nepheline syenite, colemanite, pottery stone, bentonite, ZnO, Li₂CO₃, SiO_{Subscript text}2 and 10, 15 and 20%(w/w) iron oxide (Fe₂O₃). The glaze raw materials were ground for homogeneous mixtures by ball milling for 24h. The average particle size of the mixture was 3.86 µm. The glaze bodies were carried to firing at 1,100°C at the heating rate of 2°C/min and soaking for 0.5h. Then, the glaze bodies were cooled at the cooling rate of 1°C/min and maintained at 1,080°C for 3h and then maintained at 980°C for 1h, respectively. From the experiment results, it was found that the crystallization temperatures (Tc) of franklinite (ZnFe₂O₄) and anorthite (CaAl₂Si₂O₈) depend on the concentration of iron oxide content.

Preparing of Glass-Ceramics and Recovering of Iron from Copper Slag

Authors: Zhi Hong Yang, Qiao Lin, Yong He, Hai Hui Tao, Yi Ke, Guang Dong Liao

Abstract: Copper slag, containing more than 40 wt% iron, is often used for pavement of roads, building bricks and cement etc. The level of this traditional utilization technology is very poor. In this study, a new method of comprehensive utilization of copper slag was investigated. The iron of copper slag was recovered and the residual slag was transformed into glass-ceramics within the same process involving iron reduction, iron-glass separation and glass crystallization. The experimental results indicated that the ratio of iron recovery was more than 99% and the crystalline phase of the obtained glass-ceramics was diopside. With the extension of crystallization time, the content of crystalline phase and the size of crystals of the glass-ceramics increase.

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