• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.167-183
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• 2017

Zinc oxide (ZnO) is one of the most versatile semiconductors, and one-dimensional (1D) ZnO nanostructures have attracted significant interest for use in ultraviolet (UV) lasers, photochemical sensors, and photocatalysts, among other applications. It is known that 1D ZnO nanowires can be fabricated readily owing to the anisotropic growth of ZnO along the [0001] direction. However, this type of growth results in a decrease in the surface area of the (0001) plane, which plays a vital role not only in UV lasing but also in the photocatalytic process. Thus, we attempted to synthesize ZnO crystals with an increased polar surface area by controlling the crystal growth process. The purpose of this review is to propose a simple route for the synthesis of plate-like ZnO crystals with highly enhanced polar surfaces and to explore their feasibility for use in UV lasers as well as as a photocatalyst and antibacterial agent. In addition, we highlight the recent progress made in the pilot-scale synthesis of plate-like ZnO crystals for industrial applications.

• Journal of the Korean Ceramic Society
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• v.30 no.5
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• pp.404-410
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• 1993

The characterization and sintering behavior of ZnO powders prepared by precipitation method were investigated. ZnO powders were synthesized using the aqueous solutions of ZnCl2 and NH4OH as a precipitation agent, which were crystallized in the shape of plate-like. The grain growth of ZnO(0.68${\mu}{\textrm}{m}$, 1.3${\mu}{\textrm}{m}$ and 3.4${\mu}{\textrm}{m}$) has been studied for temepratures from 100$0^{\circ}C$ to 130$0^{\circ}C$, and the rate of densification was inversely proportional to the ZnO particle size. Densification proceeded slowly by diffusion mechanisms above at 100$0^{\circ}C$. In this work, the grain growth kinetic exponent(n) was 3. The temperature dependence of ZnO grain growth was plotted, and the activation energy of grain growth was 75~85Kcal/mol.

• Korean Journal of Materials Research
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• v.17 no.9
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• pp.458-462
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• 2007

The effect of oxygen in the synthesis of oxide nanowires by using carbothermal reduction process have been studied thermodynamically and kinetically. By using laboratory air, ZnO nanowires could be fabricated in the carbothermal reduction process and a metal oxidation process. As the processing pressure decreases, the diameter of the nanowires decreases and the oxygen vacancy increases. As the processing pressure increases, the oxygen vacancy decreases and the shape of the ZnO becomes plate-like.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1179-1180
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• 2006

Y-type barium ferrite ($Ba_2Me_2Fe_{12}O_{22};$ Me=Zn, Co, Cu) expected as an electromagnetic wave absorber were prepared by the glass-ceramic method. The glasses with composition of $0.1ZnO{\cdot}0.9(xB_2O_3{\cdot}yBaO{\cdot}(1-x-y)Fe_2O_3)$ were prepared. Single-phase powders of Y type barium ferrite were obtained with the composition $0.1ZnO{\cdot}0.9(0.2B_2O_3{\cdot}0.5BaO{\cdot}0.3Fe_2O_3)$. The shape of Y-type crystals depended strongly on the heating temperature and changed from a plate-like hexagon to a complex polyhedron with increasing heating temperature. Correlation was recognized between saturation magnetization and crystal shape. Electromagnetic wave absorption characteristics was affected by the saturation magnetization and crystal shape.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.120-120
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• 2003

The metallic oxide nanomaterials including ZnO, Ga$_2$O$_3$, TiO$_2$, and SnO$_2$ have been synthesized by a number of methods including laser ablation, arc discharge, thermal annealing procedure, catalytic growth processes, and vapor transport. We have been interested in preparing the nanomaterials of Ga$_2$O$_3$, which is a wide band gap semiconductor (E$_{g}$ =4.9 eV) and used as insulating oxide layer for all gallium-based semiconductor. Ga$_2$O$_3$ is stable at high temperature and a transparent oxide, which has potential application in optoelectronic devices. The Ga$_2$O$_3$ nanoparticles and nanobelts were produced using GaN single crystals, which were grown by flux method inside SUS$^{TM}$ cell using a Na flux and exhibit plate-like morphologies with 4 ~ 5 mm in size. In these experiments, the conventional electric furnace was used. GaN single crystals were pulverized in form of powder for the growth of Ga$_2$O$_3$ nanomaterials. The structure, morphology and composition of the products were studied mainly by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM).).