• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.479-486
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• 1989

According to the phase diagram, 6Bi2O3.GeO2 composition melts congruently at 93$0^{\circ}C$ and forms a stable ${\gamma}$-6Bi2O3.GeO2 crystal phase below the melting point. But when the melt of this composition was cooled at a rate 1-15$0^{\circ}C$/min without tapping by a glass rod or impurity addition, a metastable $\delta$-6Bi2O3.GeO2 crystal phase was formed. It is due to that as the nucleation energy barrier of $\delta$-6Bi2O3.GeO2 crystals, which have more open and defective structure, is lower than that of ${\gamma}$-6Bi2O3.GeO2 crystals. When impurities or ${\gamma}$-6Bi2O3.GeO2 crystals existed in the melt, stable ${\gamma}$-6Bi2O3.GeO2 crystal phase was formed at various cooling rate. It is because of that the impurities or the ${\gamma}$-6Bi2O3.GeO2 crystals role as a seed crystal and as a result the nucleation energy barrier of ${\gamma}$-6Bi2O3.GeO2 crystals is lowered.

• Applied Science and Convergence Technology
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• v.23 no.1
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• pp.40-43
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• 2014

We investigated the growth characteristics and interfacial properties of $HfO_2$ films deposited on Ge substrate through atomic layer deposited (ALD) by using an in-situ medium energy ion scattering analysis. The growth kinetics of $HfO_2$ grown on a $GeO_2/Ge$ substrate through ALD is similar to that grown on an $SiO_2/Si$ substrate. However, the incubation period of $HfO_2$ deposition on Ge is shorter than that on Si. The $HfO_2$ grown on the GeO/Ge substrate shows a significant diffusion of Hf atoms into the substrate interface and GeO volatilization after annealing at $700^{\circ}C$. The presence of low-quality Ge oxide or suboxide may degrade the electrical performance of device.

• Journal of Ginseng Research
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• v.29 no.3
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• pp.145-151
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• 2005

This study was carried out to determine the optimal submerged culture conditions for production of ginseng root containing germanium using plant tissue culture technology. The ginseng (Panx ginseng C.A. Meyer) .cot induced by plant growth regulators of 0.5 mg/L BAP and 3.0 mg/L NAA was cultured on SH medium and the effects of various $GeO_2$ concentrations, addition time of $GeO_2$ and pH of medium were investigated on fresh weight, saponin production and germanium accumulation in ginseng root. Optimal $GeO_2$ concentrations for fresh weight, saponin and germanium content were 10, 0 and 110ppm, respectively. When $GeO_2$ was added after 2 weeks cultivation of ginseng root, germanium content was higher than that of adding $GeO_2$ at the initial cultivation time, but saponin content and fresh weight were lower. pH 5.5 was found to be the most favorable condition for the growth of ginseng root and germanium accumulation, but saponin production was best at pH 6.0.

• Korean Journal of Medicinal Crop Science
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• v.4 no.2
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• pp.101-108
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• 1996

This study was conducted to investigate the effect of growth regulators and $GeO_2$ on the induction and proliferation of callus and the effect of $GeO_2$ and citric acid on the Ge content of callus from explants and plant, Angelica koreana Max. The results obtained were summarized as follows. The callus induction was most effective on MS (Murashige and Skoog) medium containing 1. 0ppm 2, 4 - D with petiolule. The proliferation of callus was most effective at 2. 0ppm 2, 4 - D on the medium, at 2. 5ppm $GeO_2$ on the medium containing 2. 0ppm 2, 4 - D, and at $0.\;1{\sim}1mM$citric acid on the medium at pH6 containing 2. 0ppm 2, 4 - D and 2. 5ppm $GeO_2.$ The more $GeO_2$ in MS medium up to 20ppm, the more Ge content in callus. Ge content in callus was highest when the medium was supplemented with 0. 1mM citric acid and the pH of medium was low. The Ge content in plant was high in order of leaf > root > stem. Application $GeO_2$ to the soil increased Ge content in plant and application of 1mM citric acid with $GeO_2$ resulted in increasing Ge content highest in plant, but application more than l0mM citric acid resulted in Ge content decreased. Application of $GeO_2$ increased Ge content in callus and plant but had a tendency to decrease some mineral content, on the other hand application of $0.\;1{\sim}1mM$ citric acid with $GeO_2$ had a tendency to increase mineral content.

• Korean Journal of Medicinal Crop Science
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• v.3 no.3
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• pp.251-258
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• 1995

This study was carried out to find optimum concentration of germanium compounds and pH of medium on the induction and growth of callus from A. keiskei and P. ginseng and to intend to increase Ge. absorption by calli while those calli were subculturing on MS medium. Callus from a. keiskei was rarely induced under light condition. Under dark condition, callus in­duction from A. keiskei was good up to 5ppm, retarded at 50ppm of $GeO_2$, or C. E. Ge. O., and rarely done at 100 ppm of $GeO_2$ but was somewhat well at 100 ppm of C. E. Ge. O. The induction and growth of callus was good in order of pH 5. 7 > pH 5. 4 > pH 6. 0 Under light condition, the growth of callus induced from P. ginseng was poor at $1{\sim}10\;ppm$ of $GeO_2$, or C. E. Ge. O., but shooting from callus occurred frequently. Under dark condtion, the growth of callus from A. keiskei was good up to 5 ppm of $GeO_2$, or C. E. Ge. O. and was rarely done at 50 ppm of $GeO_2$, but was somewhat well even at 100 ppm of C. E. Ge. O. Shooting from callus occurred frequently in a. keiskei, especially at pH 5.7. The growth of callus from P. ginseng was poor at 10 ppm of $GeO_2$, or 50 ppm of C. E. Ge. O. Under dark condition, the amount of Ge absorption by callus induced from A. keiskei was much high­er than that from P. ginseng. The amount of Ge. absorption by callus treated with $GeO_2$, was higher than that treated with C. E. Ge. O.

• Journal of the Korean Ceramic Society
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• v.27 no.4
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• pp.567-573
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• 1990

Solidification condition for preparing transparent ${\gamma}$-6Bi2O3.GeO2 polycrystals by unidirectional solidification of melt, were investigaetd and the properties of the polycrystals prepared were measured. The ${\gamma}$-6Bi2O3.GeO2 polycrystals showing transparency like a single crystal were obtained by the unidirectional solidification of ${\gamma}$-6Bi2O3.GeO2 melt at a solidification rate of 0.5mm/h under a thermal gradient of 12$0^{\circ}C$/cm. The transparent polycrystals obtained showed the same photoconduction and optical activity as the ${\gamma}$-6Bi2O3.GeO2 single crystals grown by Czochralski method. But the electro-optic effect of polycrystals was heterogeneous because the colummar ${\gamma}$-6Bi2O3.GeO2 crystals were not oriented to the particular crystallographic direction.

• Journal of the Korean Ceramic Society
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• v.28 no.12
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• pp.981-988
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• 1991

Various crystal defects such as voids, inclusions dislocations, stacking faults and precipitates were observed in the Czochralski-grown Bi12GeO20 crystals. Particularly, precipitates were found in the whole crystals. The phase of these precipitates was identified as Bi4Ge3O12 by EPMA and transmission electron microscopy. The precipitates were produced by pulling rapidly from a non-stoichiometric charge. During the pulling of Bi12GeO20 crystals, the melt composition of stoichiometric charge was changed Bi-deficent with gradual volatilization of Bi2O3. Precipition of the second phase may have been affected by an abrube thermal stress. By adding excess Bi2O3 into the stoichiometric batch, the precipitation of Bi4Ge3O12 was suppressed. At a pulling speed of 2 mm/hr, clear and precipitate from crystals of Bi12GeO20 were grown from the melt of the Bi2O3 excess charge.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.166-173
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• 2010

In order to obtain the basic information for agricultural utilization of germanium (Ge), the growth characteristics, Ge uptake, and grain quality of rice plant (Hopyungbyeo) were investigated under different germanium ($GeO_2$, and commercial Ge) treatments in paddy field. Phytotoxicity was detected in $GeO_2$ treatment but not in commercial Ge treatment. The grain yield was greater in the order of control treatment > commercial Ge treatment > $GeO_2$ treatment. The dry weight was greater in order of control treatment > $GeO_2$ treatment ${\geq}$ commercial Ge treatment. The Ge content of leaf in $GeO_2$ treatment was 6 times (177 mg $m^{-2}$) higher than that in commercial Ge treatment. The Ge content in rice bran was not different in $GeO_2$, and commercial Ge treatments. The Ge contents of brown rice in$GeO_2$, and commercial treatments were 40.9, and 31.1 mg $kg^{-1}$, respectively. The Ge uptake rates in rice plant was higher in the order of leaf > rice bran > brown rice > stem > root. Under $GeO_2$, 15.56% of Ge absorbed into plant with 11.1% in leaf, 1.6% in stem, 0.03% in root, 2.2% in rice bran and 0.73% in brown rice. Under commercial Ge treatment, 5.19% of Ge absorbed into plant with 1.8% in leaf, 0.46% in stem, 0,01% in root, 2.2% in rice bran, and 0.71% in brown rice. Based on these results, the Ge contents in polished rice in commercial Ge treatment were higher than those in $GeO_2$ treatment. However, the Ge contents of rice grain (containing rice bran and polished rice) in $GeO_2$ treatment were higher than those in commercial Ge treatment.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.346-352
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• 2000

We investigated the oxidation behavior of poly $Si_{1-x}Ge_x$ films (X=0.15, 0.42) at $700^{\circ}C$ in wet oxidation ambients and analyzed the oxide by XPS, RBS, and cross-sectional TEM. In the case of poly $Si_{0.85}Ge_{0.15}$ films, $SiO_2$ was formed on the poly $Si_{1-x}Ge_x$ films and Ge was rejected from growing oxide, subsequently leading to the increase of Ge content. In the case of poly $Si_{0.58}Ge_{0.42}$ films, we found that $SiO_2-GeO_2$ were formed on the poly $Si_{1-x}Ge_x$ films due to high Ge content. Finally, we proposed the oxidation model of poly $Si_{1-x}Ge_x$ films.

• Journal of the Korean Ceramic Society
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• v.32 no.11
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• pp.1269-1275
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• 1995

Effects of GeO2 addition on the thermal and structural stabilities of PbO-Bi2O3-Ga2O3 glasses were studied. Thermal stabilities, as assessed by the weighted thermal stability factors [(Tx-Tg)/Tg], increased with GeO2 concentraton from 0.097 to 0.210 with the addition of 20 mol% GeO2. Increasing GeO2 content resulted in the decrease of apparent density, molar volume, refractive index and thermal expansion. On the other hand, IR transmission cut-off (λT=50%) moved from 6.73${\mu}{\textrm}{m}$ for the ternary PbO-Bi2O3-Ga2O3 glass to shorter wavelength side, 5.98${\mu}{\textrm}{m}$ for a glass containing 20mol% GeO2. There were little change with GeO2 content, however, in the activation energies for the viscous flow of approximately 140 kcal/mole within the temperature interval of 300~50$0^{\circ}C$. Addition of GeO2 to PbO-Bi2O3-Ga2O3 glasses enhanced the thermal and structural stabilities significantly at the expense of their infrared transmittance. An appropriate compsomise between these two opposite trends should be made following the specifications of the final applications.