• Journal of the Korean Ceramic Society
• /
• v.22 no.5
• /
• pp.3-8
• /
• 1985

$ZrO_2$ single crystals were grown by slow cooling flux method using Borax $(Na_2B_4O_7)$ and KF as flux agent. The morphology of grown crystals was observed under a petrographic microscope. And the results obtained from grow crystals were as follows : 1. $ZrO_2$ crystals grown in the present work are morphologically divided into two shapes ; tabular and den-dritic crystals. 2. The maximum size of the crystals grown reaches to $4{\times}15{\times}2mm$ on edge into length at $ZrO_2$ 15mole% Borax 50mole% and KF 35mole% 3. $ZrO_2$ single crystals grown by flux method have monoclinc structure. 4. The content of KF as flux agents was limited by 60mole% KF. Since alumina crucible was heavily damaged by increasing KF content.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.34 no.3
• /
• pp.79-85
• /
• 2024

We investigated the crystal structural property and chemical bonding nature of cellulose nanocrystal extracted directly from cotton cellulose using high-pressure homogenizer. The nanowire-like cellulose nanocrystals were randomly distributed in the form of a dense mesh. Based on calculating the interplanar distance of the Bragg-diffracted crystal plane observed through X-ray diffraction (XRD) analysis, it was found that the cellulose nanocrystals formed by high-pressure homogenizer had a monoclinc crystal structure, corresponding to the cellulose Iβ sub-polymorph. Solid-state nuclear magnetic resonance (NMR) analysis for the quantitatively evaluation of the amorphous region in cellulose nanocrystals revealed that the crystallinity index of cellulose nanocrystals was calculated to be 53.06 %. The O/C ratio of the surface of cellulose nanocrystal was estimated to be 0.82. Further analysis showed that chemical bonds of C-C bond or C-H bond, C-O bond, O-C-O bond or C=O bond, and O-C=O bond were the main chemical bonding states of the cellulose nanocrystal surface.

• Journal of the Korean Ceramic Society
• /
• v.33 no.4
• /
• pp.432-440
• /
• 1996

ZrO2 gel was prepared under pH 10 alkaline condition by sol-gel process and was investigated as a function of calcination temperature and effect of calcination temperature on cobalt adsorption capacity. The ZrO2 powder prepared by sol-gel process was calcined at 600, 800, 1000, 1200, 140$0^{\circ}C$ and analyzed by X-ray diffractometry. SEM specific surface area by BET nitrogen adsorption FT-IR and TG-DTA technique. It was shown that cobalt adsorption capacity of ZrO2 prepared under pH 10 alkaline condition and then calcined at $600^{\circ}C$ in high temperature was determined to be larger than that of ZrO2 at various calcination temperature. The specific surface area of ZrO2 calcined at $600^{\circ}C$ was 24.03m2/g and cobalt adsorption capacity at 25$0^{\circ}C$ high-temperature water was 0.16m-eq/g.