• 한국세라믹학회지
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• 제36권2호
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• pp.136-144
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• 1999

텅스템브론즈형 고주파 유전체의 $BaORe_2O_3TiO_2$(BLT)와 $BaO(Nd({0.77}Y_{0.23})_2O_34TiO_2(B(NY)T)$의 결정구조를 Rietveld 정밀화법으로 분석하였다. 양이온은 X-선 데이터로부터, 산소이온은 중성자 데이터로부터 정밀화한 'combined법'에 의해 가장 신뢰성이 높은 결정구조분석 결과를 얻었다. Mateeva 등이 처음 제시한 결정구조의 결정학적 모순점을 해결하였다. BaORe2O34TiO2(Re=La, Nd, Y) 유전체는 $3\times2$개의 페롭스카이트 블록과 이 블록사이에 형성된 4개의 pentagon-channel로 이뤄진다. Ti-O6팔면체는 tilted 및 변형된 구조를 갖고 있고, 이에 의해 같은 z-층에 있는 Ba 및 Re 이온의 변위되어 초격자(c$\approx$ 7.6$\AA$)를 형성된다. Re 이온반경이 작은 B(NY)T의 Ti-O6 팔면체가 tilting 및 변형이 큰 것으로 나타났다. 유전상수 $\varepsilon_{\gamma}$과 온도계수 $au_\varepsilon$은 BLT의 경우 각각 $109.5, -180 ppm/^{\circ}C$였고, B(NY)T 경우 $76, +40ppm/^{\circ}C$이었다. Re 이온 크기가 작은 시료의 $\tau$$\varepsilon$이 +값을 나타내었다. 복합 페롭스카이트에서 관찰되는 $\tau_\varepsilon$과 팔면체 tilting과의 관계를 본 텅스텐 브론즈 구조재료에서 고찰하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.289-290
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• 2006

[ $SrTiO_3$ ] is usually added as shifters in order to move the $T_C$ of $BaTiO_3$ to lower temperatures because it is well established that the $T_C$ of $BaTiO_3$ decreases linearly with a solid solution of $Sr^{+2}$ in place of $Ba^{+2}$. It is not fully understood yet, however, how $SrTiO_3$ influences on the peak value of the dielectric constant $(\varepsilon_{max})$ at the $T_C$ of $BaTiO_3$. This research reports the effect of $SrTiO_3$ addition on εmax at the $T_C$ of $BaTiO_3$ ceramics. Based on the chemical composition and the grain size dependence of the dielectric property of $BaTiO_3$ ceramics, functionally graded $(Ba,Sr)TiO_3$ composites were designed and fabricated. Multi-layered $(Ba,Sr)TiO_3$ composites with a compositional gradient of $SrTiO_3$ exhibited a low temperature coefficient and high dielectric constant in a wide temperature range.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.190-195
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• 1995

Temperature dependences of the dielectric constant K(T), remanent polarization $P_{r}$, (T), effective birefringence overbar .DELTA.n(T), transmitted light intensity and quadratic electro optic coefficient R(T) of the two-stage sintered xBa(L $a_{1}$2/N $b_{1}$2/) $O_{3}$-(1-x)Pb(Z $r_{y}$ $Ti_{1-y}$) $O_{3}$(x=0.085, 0.09, 0.40.leq.y.leq.0.70) ceramics were investigated. Increasing the PbZr $O_{3}$ contents, the crystal structure of a specimen was changed from a tetragonal phase to a rhombohedral and cubic phase, and the phase transition was showed a diffuse phase transition(DPT) characteristics. In the compositions which located on the PE-FE phase boundary, the discrepancy was observed between the Curie temperature and temperature which a microscopic polarization and effective birefringence were disappeared.red.d.

• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.311-315
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• 2017

The perovskite system $(Ba^{2+}{_{1-x}}La^{3+}{_x})Fe^{3+}{_{1-t}}Fe^{4+}{_t}O_{3-y}$ (y = (1 - x --t)/2) having a composition of x = 0.0, 0.1, 0.2, and 0.3 showedean increase in $Fe^{4+}$ mole ratios with an increase in oxygen partial pressure ($N_2{\rightarrow}air{\rightarrow}O_2$), and with an increasefin s, the $Fe^{3+}$ quantity decreased and oxygen content (3-y value) increased. For each N sampls heat-treated in $N_2$ gas, a considerable weight gain, i.e.g a steadynincrease if oxygen content, was observed in the TGA data on the cooling process. The conductivity values at a constant temperature were in the order of $N_2$$O_2$; the respective log ${\sigma}$ values (${\Omega}^{-1}{\cdot}cm^{-1}$) at 323 K of the BL0 sample were -5.75 (BL0-N), -3.39 (BL0-A), and -0.53 (BL0-O). The mixed valencies of $Fe^{3+}$ and $Fe^{4+}$ ions in each sample were also confirmed by both the oxidation curve above 350 mV and the cathodic reduction curve below 200 mV from cyclic voltammetry.

• 한국화재소방학회논문지
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• 제9권2호
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• pp.29-36
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• 1995

In this study, the effect of Mn $O_2$ additive on the electrical characteristics of PZN-PSS-PZT Pyroelectric materials for the fire detactor was studies. PZT ceramics used this experimental is 4 composite system $[$Pb(Z $n_{1}$3/ N $b_{2}$3/) $O_3$＋Pb(S $n_{1}$3/ S $b_{2}$3/) $O_3$＋PbTi $O_3$＋PbZr $O_3$$]$The dielectric constants and dissipation factors decreases as to Mn $O_2$ concentration increases. At the Mn $O_2$ 0.5($\omega$t%), Pyroelectric coefficient shows 8(10$^{-8C}$$\textrm{cm}^2$$^{\circ}C$) which have the highst value among other additive contents. It is found that output voltage shows maximum peck at Mn $O_2$0.7($\omega$t％) is associated with the higher pyroelectric coefficient and Lowered dielectric constant.t.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 추계총회,초청강연,특별강연,연구발표회
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• pp.41.2-41
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• 2000

• 광물과산업
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• 제25권
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• pp.1-10
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• 2012

본 연구에서는 경북 울진 보암광산의 리튬광을 대상으로 고품위 리튬 정광 생산을 위한 부유선별 연구를 수행하였다. 리튬의 근원광물은 Lepidolite (0.99% $Li_2O$)이며, 주요 맥석광물은 $SiO_X$를 포함하는 규산염 광물(quartz, muscovite)과 방해석(Calcite)이 존재하였다. 따라서 음이온포수제를 이용하여 방해석을 먼저 부유시켜 제거하고, 규산염 광물을 억제하고 리튬 광물을 부유시키는 공정을 적용하였다. 리튬광물 부유선별에서 포수제는 아민계통의 양이온 포수제(Armac-T, Armac-C, Armafloat-18, Armafloat-1597) 중 Armac-T가 가장 효과적이었다. 실험결과 최적 조건인 포수제(Armac-T) 100g/t, 기포제(AF65) 50g/t, 억제제($Na_2SiO_3$) 600g/t, (Lactic acid) 100g/t, 광액농도 20%solids, pH 5.5 그리고 정선횟수 2회에서 $Li_2O$의 품위와 회수율이 각각 4.33%와 80.3%인 결과를 얻었다.

• 분석과학
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• 제17권3호
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• pp.282-288
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• 2004

Inclusion selectivities of the cyanocadmate host complexes with ammonium oniums, $[Cd_x(CN)_{2x}][onium{\cdot}zG]$ (onium = $NMe_3Et^+$, $NMeEt{_3}^+$ and $NEt{_4}^+$, G = guest), have been investigated for $C_6H_6$ (B), PhMe (T), PhEt (E), ortho (O), meta (M), and para (P) isomers of $C_6H_4Me_2$ as the aromatic guest molecules. From the binary, ternary, quaternary and quinary mixed guests of B, T, E, O, M and P, the order of preference in the $NMe_3Et+$-host is $B{\gg}$T>P${\fallingdotseq}O{\fallingdotseq}M$ and E>O${\gg}P{\fallingdotseq}M$; in the $NMeEt{_3}^+$-host is T>B>P${\gg}O{\fallingdotseq}M$ and E>P${\gg}$M>O; in the $NEt{_4}^+$-host is $B{\gg}T{\fallingdotseq}O{\fallingdotseq}M{\fallingdotseq}P$. However, the $NEt{_4}^+$-host complexes of E, O, M and P mixed-guests were not obtained. These inclusion selectivities were compared to our previous results of the $NMe{_4}^+$-host; T>B>P${\gg}$M>O and E>P${\gg}$M>O.

• 한국재료학회지
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• 제6권2호
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• pp.228-234
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• 1996

BzCuO2 의 생성 자유에너지를 이중 이온교환된 Ba2+-$\beta$/$\beta$"-AI2O3를 전해질로 사용하여 다음과 같은 생성셀로부터 측정하였다. Au(po2=10-3)/Au+BaCuO2+CuO// Ba2+-$\beta$/$\beta$"-Au이 갈바닉셀에서 BzCuO2 의 임의의 생성식과 생성자유에너지는 다음과 같다. BaO+CuO=BaCuO2 $\Delta$fGo/kJ.mol-1=-77.3-3.3x10-3T/K.3x10-3T/K.

• 대한화학회지
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• 제45권3호
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• pp.264-267
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• 2001