무알칼리 다성분 La_2O_3-Al_2O_3-SiO_2 유리의 조성과 몇 가지 물성의 관계

강은태,양태영,황종희 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.2

Non-Alkali multicomponent La_2O_3-Al_2O_3-SiO_2 glasses has been designed and analyzed on the basis of a mixture design experiment with constraints. Fitted models for thermal expansion coefficient, glass transition temperature, Young’s modulus, Shear modulus and density are as follows:α(/℃) = 8.41 × 10^(−8)x_1+5.72 × 10^(−7)x_2+2.13× 10^(−7)x_3+1.09 × 10^(−7)x_4+1.10× 10^(−7)x_5+1.15 × 10^(−7)x_6+2.72 × 10^(−8)x_7+2.41 × 10^(−7)x_8 −1.08×10^(−8)x_1x_2+4.28×10^(−8)x_3x_7−2.02×10^(−8)x_3x_8−1.60×10^(−8)x_4x_5−2.71×10^(−9)x_4x_8−2.19×10^(−8)x_5x_6−3.89×10^(−8)x_5x_7T_g(℃)=7.36x_1+15.35x_2+20.14x_3+8.97x_4+13.85x_5+4.22x_6+28.21x_7−1.44x_8−0.84x_2x_3−0.45x_2x_5−1.64x_2x_7+0.93x_3x_8−1.04x_5x_8−0.48x_6x_8 E(GPa)=2.04x_1+14.26x_2−1.22x_3−0.80x_4−2.26x_5−1.67x_6−1.27x_7+3.63x_8−0.24x_1x_2−0.07x_2x_8+0.14x_3x_6−0.68x_3x_8+0.29x_4x_5+1.28x_5x_8G(GPa)=0.35x_1+1.78x_2+1.35x_3+1.87x_4+9.72x_5+29.16x_6−0.99x_7+3.60x_8−0.48x_1x_6−0.50x_2x_5+0.08x_3x_7−0.66x_3x_8+0.94x_5x_8ρ(g/cm^3)=0.09x_1+0.51x_2−4.94×10^(−3)x_3−0.03x_4+0.45x_5−0.07x_6−0.10x_7+0.07x_8−9.60×10^(−3)x_1x_2−8.20×10^(−3)x_1x_5+2.17×10^(−3)x_3x_7−0.03x_3x_8+0.05x_5x_8The optimal glass composition similar to the thermal expansion coefficient of Si based on these fitted models is 65.53SiO_2 ·25.00Al_2O_3·5.00La_2O_3·2.07ZrO_2·0.70MgO·1.70SrO.

혼합물계획법에 의한 Li2O-ZrO2-SiO2 유리의 이온전도도와 조성의 관계

강은태,김명중,김재동 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.4

The ionic conductivity of Li2O-ZrO2-SiO2 glasses has been designed and analyzed on the basis of a mixture design experiment with constraints. Fitted models for the activation energy and the ionic conductivity are as follows: Q(kJ⁄mol) 54.8565x1 144.825x2 133.846x3 170.908x1x3 334.338x2x3 = + + – – logσ(300K) 5.00245x1 – 1.17876x2 15.5173x3 17.4522x1x3 The electrical properties are very sensitive to the ratio of Li2O/SiO2. The effect of ZrO2 is less than that of this ratio but ZrO2 component attributes to the reduction of the activation energy. The optimal composition for best ionic conduction based on these fitted models is 55Li2O·10ZrO2·35SiO2. Its activation energy and ionic conductivity at 300 K are 46.98 kJ/mol and 1.08×10−5 Ω−1·cm−1, respectively.

Electron Spin Resonance Study of Fe3+ in (40-x)BaO?Fe2O3?0P2O5 Glasses

강은태 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.3

(40-x)BaO·xFe2O3 · 60P2O5 glasses with 5≤x≤35 mol% were investigated by ESR spectroscopy. Two resonances observed near g=2.0 and g=4.3. The line at g=4.3 disappeared with the increase of the Fe2O3 content. The resonance at displayed characteristic signal consisting of superposed extremely broad and narrow components. The broader one indicates the presence of the association of two or more Fe 3+ ions, antiferromagnetically and the narrow one is related to the microclusters involving iron ions. Temperature dependence of the ESR integrated intensity revealed short-range antiferromagnetic character for x≥15 mol%. (40-x)BaO·xFe2O3 · 60P2O5 glasses with 5≤x≤35 mol% were investigated by ESR spectroscopy. Two resonances observed near g=2.0 and g=4.3. The line at g=4.3 disappeared with the increase of the Fe2O3 content. The resonance at displayed characteristic signal consisting of superposed extremely broad and narrow components. The broader one indicates the presence of the association of two or more Fe 3+ ions, antiferromagnetically and the narrow one is related to the microclusters involving iron ions. Temperature dependence of the ESR integrated intensity revealed short-range antiferromagnetic character for x≥15 mol%.

(40-x)BaO⋅xFe₂O₃⋅60P₂O₅ 유리의 Fe³⁺이온에 관한 전자스핀공명 연구

강은태,Kang, Eun-Tae 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.3

(40-x)BaO${\cdot}xFe_2O_3{\cdot}60P_2O_5$ glasses with $5{\leq}x{\leq}35mol%$ were investigated by ESR spectroscopy. Two resonances observed near g=2.0 and g=4.3. The line at g=4.3 disappeared with the increase of the $Fe_2O_3$ content. The resonance at $g{\approx}2.0$ displayed characteristic signal consisting of superposed extremely broad and narrow components. The broader one indicates the presence of the association of two or more $Fe^{3+}$ ions, antiferromagnetically and the narrow one is related to the microclusters involving iron ions. Temperature dependence of the ESR integrated intensity revealed short-range antiferromagnetic character for $x{\geq}15mol%$.

실험계획법에 의한 $Na_2O-Al_2O_3-SiO_2$계 유리의 조성과 물성관계

강은태 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.10

A relation between composition and properties of Na2O-Al2O3-SiO2 glasses was investigated with application of the extreme vertical design. Properties investigated in this study include glass transition temperature density refractive index thermal expansion electrical conductivity bending strength and hardness, Most of the quadratic models fitted on property data were statistically significant. The properties estimated from the fitted equation agreed well with the measured properties. The estimated properties were compared with those reported by other investigators. Additional composition except for those of extreme vertices were needed to yield a slightly better result for the simple system such as a temary system. In addition an optimal composition on each property could be calculated by using optimization technique on result obtained from the fitted quadratic models.

MgO.$P_2O_5$ 유리의 수분 측정

강은태,박용완 한국세라믹학회 1986 한국세라믹학회지 Vol.23 No.3

Infrared has been used in determination of water in magnesium metaphosphate glasses. The method consisted of measuring the weight loss and the variation in absorption coefficient at 3, 200$cm^{-1}$. The molar absorptivity of water in magnesium metaphophate glasses was found to 76.9ι$mol^{-1} cm^{-1}$ Using the value for $\varepsilon$, A and Δ$\upsilon$H of the hydroxyl band in the spectra of magnesium metaphosphate. The molar absorptivity of the hydroxyl absorption band at 3, 3130-2, $925cm^{-1}$ in the spectra of MgO.$P_2O_5$ system glasses could be computed. And a variation of molar absorptivity against the MgO/P2O5 ratio has not been shown regulation.

Gd-doped Ceria의 산소이온 확산에 대한 분자동력학법 연구

강은태,김희승 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.8

Doped ceria의 전기전도도는 도핑 원소의 종류와 양에 큰 의존성을 가지고 특정 조성에서 최대 전도도 값을 가지며 높은 dopant 농도에서는 전기전도도는 감소한다. 이런 현상은 dopant와 산소 빈자리 사이의 회합 형성과 관련이 있다고 알려져 있다. 그러나 Gd 이온이 도핑된 ceria의 경우 주된 회합종이 (2G $d_{Ce}$ $V_{o}$ )인지 (G $e_{Ce}$ $V_{o}$ ) 인지는 명확하게 알려져 있지 않다. 본 연구에서는 회합분포가 전기전도도에 미치는 영향을 연구하기 위해 결함의 회합종과 분포가 다른 3가지 경우에 대해서 시뮬레이션을 행하였다. 분자동력학법을 이용하여 다양한 온도와 다른 회합분포의 경우에 대해 산소 확산계수가 계산되어졌으며, 계산된 산소 확산계수는 실험적으로 결정된 bulk 전도도로부터 얻어진 산소 확산계수와 비교되어졌다. 그 결과 (2G $d_{Ce}$ $V_{o}$ )와 (G $e_{Ce}$ $V_{o}$ ) 회합이 공존하며 이들이 통계학적으로 이항 분포를 가지는 경우가 실험적으로 보고된 값과 가장 일치하는 결과를 얻을 수 있었다.

Rietveld Refinement에 의한 NASICON의 결정구조

강은태,정훈,최진삼,최진범,Kang, Eun-Tae,Cheong, Hoon,Choi, Jin-Sam,Choi, Jin-Beom 한국재료학회 1996 한국재료학회지 Vol.6 No.5

고상반응법과 sol-gel법으로 제조된 NASICON의 상온과 25$0^{\circ}C$에서의 X선 회절 데이터를 리트벨트 분석을 행하였다. monoclinic에서 rhombohedral로 상전이가 일어나도 원자들의 변위는 매우 작았다. 이들 상간의 ZrO6 팔면체와 Si(P)O4 사면체고 구성된 골격은 다소 다르게 나타남으로 인하여 Na 이온의 자리도 변하였다. 이들 방법으로 제조된 NASICON은 Zr이 부족한 비화학양론 화학식, Na 1+x+4yZr2-xSixP3-xO12으로 표현될 수 있었다. 제조법에 따라 Na 이온들의 자리 점유율이 변화하였다. 상온에서는 Na(1)과 Na(3)자리의 자리 점유율의 합이 거의 1에 가까웠으나, 25$0^{\circ}C$에서는 Na(1)과 mid Na 자리를 단위 화학식 당 한 개를 약간 상회하는 Na 이온이 점유하였다. 상온과 25$0^{\circ}C$에서의 Na 이온의 이동 경로가 다름을 알 수 있었다. 또한 25$0^{\circ}C$에서는 Na(1)자리와 Na(2)자리 사이에 mid Na가 존재하며, 이 자리가 Na 이온의 이동에 중요한 역할을 함을 알 수 있었다.

Composition-property Relationships of Enamel Glass for Low Carbon Steel

강은태,김종포,조용현,박선미 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.3

The relationship between composition and properties of enamel glass was investigated by introducing a mixture design. The enamel glass was manufactured by mixing various components under the following constraints: 45 ≤ SiO2≤ 55, 10 ≤ B2O3≤ 18,6 ≤ Na2O ≤ 15, 1 ≤ Li2O ≤ 6, 5 ≤ K2O ≤ 10, 0 ≤ TiO2≤ 8, 0 ≤ ZrO2≤ 8, 13.3MO (mol %). A mathematical model for the calculation of some properties of enamel glasses as a function of their composition was developed by the experimental statistical method. The results showed that the proposed model with the experimental measurement were in good agreement and the mixture experimental design was an effective method for optimizing the composition of the enamel glass with respect to its properties.

융액의 일방향응고에 의한 배향성(Pb,Ln)(Ti,Mn)O₃다결정체의 제조(Ln=희토류)

강은태 慶尙大學校 1984 論文集 Vol.23 No.2

Sintered batch mixtures of the compositions of PbO·TiO2 and 0.88 PbO·0.08 Ln2O3(Ln;rare-earth) 0.98TiO2·0.02MnO2 were melted and unidirectionally solidified upwards at rate of 9mm/br. in a modified Bridgman furnace. The apparent porosity of transverse sections of the solidified ingots increased as trivalent rare earths substitute for Pb2+. The dielectric constants and the Curie temperature of transverse sections of the solidified ingots decreases and increased with decreasing ionic radii of the rare earths respectively. The difference between kp and kt increases as rare-earth ionic radii decreases.