• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.627-632
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• 2010

In this paper the effect of the structure, particle size, morphology of nanofibers and nanoparticles for the electrochemical characteristics of $Li_4Ti_5O_{12}$ was investigated. The $H_2Ti_2O_5{\cdot}H_2O$ synthesized in hydrothermal treatment from a NaOH treatment on $TiO_2$ by ion exchange processing with HCl solutions. After the $Li_4Ti_5O_{12}$ nanofibers synthesized in hydrothermal treatment of $H_2Ti_2O_5{\cdot}H_2O$ and $LiOH{\cdot}H_2O$. The hydrogen titanate precursor prepared by ion exchange processing with 0.1~0.3M HCl solutions and the final products calcined at $350^{\circ}C{\sim}400^{\circ}C$. The $Li_4Ti_5O_{12}$ nanofibers showed well reversibility during the insertion and extraction of Li, good cycle performance, high capacity and low electrochemical reaction resistance than nanoparticles. also c-rate exhibited a discharge capacity of 172 mAh/g at 0.2C and 115mAh/g at 5C, which is the 77%, 67% of that obtained in the process charged, discharged at 0.2C.

• Journal of Powder Materials
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• v.26 no.5
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• pp.405-409
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• 2019

Piezoelectric ceramic specimens with the $Pb(Mg_{1/3}Nb_{2/3})_{0.65}Ti_{0.35}O_3$ (PMN-PT) composition are prepared by the solid state reaction method known as the "columbite precursor" method. Moreover, the effects of the $Li_2O-Bi_2O_3$ additive on the microstructure, crystal structure, and piezoelectric properties of sintered PMN-PT ceramic samples are investigated. The addition of $Li_2O-Bi_2O_3$ lowers the sintering temperature from $1,200^{\circ}C$ to $950^{\circ}C$. Moreover, with the addition of >5 wt.% additive, the crystal structure changes from tetragonal to rhombohedral. Notably, the sample with 3 wt.% additive exhibits excellent piezoelectric properties ($d_{33}=596pC/N$ and Kp = 57%) and a sintered density of $7.92g/cm^3$ after sintering at $950^{\circ}C$. In addition, the sample exhibits a curie temperature of $138.6^{\circ}C$ at 1 kHz. Finally, the compatibility of the sample with a Cu electrode is examined, because the energy-dispersive X-ray spectroscopy data indicate the absence of interdiffusion between Cu and the ceramic material.

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.85-95
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• 2023

In recent years, solid-state Li metal batteries (SSLBs) have attracted significant attention as the next-generation batteries with high energy and power densities. However, uncontrolled dendrite growth and the resulting pulverization of Li during repeated plating/stripping processes must be addressed for practical applications. Herein, we report a plastic-crystal-based polymer/ceramic composite solid electrolyte (PCCE) to resolve these issues. To fabricate the one-side ceramic-incorporated PCCE (CI-PCCE) film, a mixed precursor solution comprising plastic-crystal-based polymer (succinonitrile, SN) with garnet-structured ceramic (Li₇La₃Zr₂O₁₂, LLZO) particles was infused into a thin cellulose membrane, which was used as a mechanical framework, and subsequently solidified by using UV-irradiation. The CI-PCCE exhibited good flexibility and a high room-temperature ionic conductivity of over 10^-3 S cm^-1. The Li symmetric cell assembled with CI-PCCE provided enhanced durability against Li dendrite penetration through the solid electrolyte (SE) layer than those with LLZO-free PCCEs and exhibited long-term cycling stability (over 200 h) for Li plating/stripping. The enhanced Li⁺ transference number and lower interfacial resistance of CI-PCCE indicate that the ceramic-polymer composite layer in contact with the Li anode enabled the uniform distribution of Li⁺ flux at the interface between the Li metal and CI-PCCE, thereby promoting uniform Li plating/stripping. Consequently, the Li//LiFePO₄ (LFP) full cell constructed with CI-PCCE demonstrated superior rate capability (~120 mAh g^-1 at 2 C) and stable cycle performance (80% after 100 cycles) than those with ceramic-free PCCE.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.4
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• pp.147-152
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• 2011

ZnO nanorods fabricated on a Zn substrate pre-coated with ZnO as a seed layer by the hydrothermal method were studied mainly as a function of ZnO precursor concentration. Characteristic features by using field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were investigated to define the changed micro-structure and crystalline phase of the ZnO nanorods according to the experimental conditions. The nanorod morphology strongly depended on the precursor concentration. For example, ZnO nanorods vertically aligned with a hexagonal (002) oriented structure with a diameter of 600~700 nm and length of $6.75{\mu}m$ were clearly observed at the highest concentration of 0.015 M. The strong hexagonal structure was believed to be associated with the highest photoluminescene (PL) intensity and a promising voltage value of ca. 6.069 V at $1000{\mu}A$.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.209-210
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• 1999

오존 precursor인 NOx의 배출기준은 점차 강화되고 있고 NOx의 처리기술로는 선택적 촉매환원법 (Selective Catalytic Reduction; SCR)이 가장 널리 사용되고 있다. 국내 SCR 적용공정의 경우, 100% 수입에 의존하고 있어 support 촉매의 국산화가 절실히 요구되고있다. 이에 본 연구에서는 support로 섬유형 세라믹 필터를 사용하여 CuO, V$_2$O$_{5}$ 촉매를 담지시켜 NOx의 제거실험을 수행하였다.(중략)

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.55.1-55.1
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• 2000

• Journal of the Korean Ceramic Society
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• v.55 no.6
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• pp.625-634
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• 2018

In this work, we describe a novel and simple technique to produce non-hydrate surfactant complexes for the formation of highly crystalline fatty acid modified SPIONs by thermolysis of iron oleate (FeOl) complexes in a non-coordinating solvent. FeOl complexes were prepared by direct coordination of iron ions and carboxylic acid; thus, we could control the stoichiometric composition of the precursor by changing the molar ratio of fatty acid and metal ions. The discrete thermal behaviors and chemical coordination of the intermediate non-hydrated FeOl were studied by thermo-analytic techniques including differential scanning calorimetry, thermal gravimetric analysis, and Fourier transform infrared spectroscopy.

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.927-933
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• 1994

Alumina composite membranes were prepared by chemical vapor deposition (CVD) using aluminum-tri-isopropoxide as a precursor. Porous alumina supports were used in deposition, which were in disk shape with mean pore diameter of 0.1 ${\mu}{\textrm}{m}$ and prepared by slip-coasting process. film deposition morphology on porous support was simulated through depositing alumina film on polycrystalline silicon pattern, and its step coverage observed by SEM showed one deviated from uniform step coverage. N2 permeability through composite membranes and the pressure dependence decreased as the deposition time increased. Initially, the N2 permeability of the top layer was tend to decrease rapidly, and then the degree of decrease in N2 permeability was tend to diminish with deposition time. The N2 permeability increased with heat treatment temperature and the crack was generated in top layer at 100$0^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.29 no.12
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• pp.963-969
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• 1992

This paper describes the feasibility for a direct production of zinc oxalate powders from zinc-loaded D2EHPA solutions combining the purification and the precipitation in one operation unit. This process has the potential as an alternative to conventional method for the synthesis of zinc oxide precursor particles from the hydrometal-lurgical processes. Zinc was extracted into D2EHPA in kerosene and then zinc-loaded D2EHPA solution was emulsified with oxalic acid-HCl solution to precipitate zinc oxalate powder, which was readily calcined to zinc oxide. The precipitation kinetics and yield were sensitive to experimental conditions. The morphology, size and size distribution of the zinc oxalate powders varied with zinc/oxalate ion riatio, temperature, and the presence of SPAN 60, which affected nucleation, growth, and the emulsion characteristics.

• Journal of the Korean Ceramic Society
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• v.32 no.4
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• pp.489-497
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• 1995

The DDS((CH3)2SiCl2)＋H2 gas mixture, where C atoms exist in excess in the molecules, was used for chemical vapor deposition of SiC in order to prevent codeposition of free Si in MTS(Ch3SiCl3)＋H2 system. The deposition rate was more rapid than MTS, however differ from that of MTS, it decreased after shwoing a maximum at 140$0^{\circ}C$. The stoichiometry was highly improved by using the DDS as a precursor, although there exist a little pyrolytic C at 150$0^{\circ}C$. The preferred orientation was (220) in MTS, however, it changed to (111) in DDS. The microstructure of the layer deposited at lower temperature were dense, however it grew coarse with the increase in the temperature.