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$Nd_{1-x}Ba_xFeO_{3-y}$계의 비화학량론과 물리적 성질에 관한 연구
장순호,유광현,김성진,최승철,장순호,Chang, Soon Ho,Yu, Gwang Hyeon,Kim, Seong Jin,Choe, Seung Cheol,Jang, Sun Ho 대한화학회 1994 대한화학회지 Vol.38 No.8
$Nd_{1-x}Ba_xFeO_{3-y}$계에 대한 각 조성의 시료를 1200$^{\circ}C$ 대기압하에서 반응물을 가열하여 합성하였고 X-선 분말 회절분석을 통하여 고용체가 합성되었음을 확인하였다. X-선 회절분석 결과 x = 0.00과 0.25는 팔면체장이 뒤틀린 orthoferrite형의 사방정계이며, x = 0.50과 0.75의 조성을 갖는 화합물은 단순입방정계이다. 고용체내의 Fe이온은 $Fe^{3+}$와 $Fe^{4+}$이온의 혼합원자가 상태로 존재하기 때문에 $Fe^{4+}$이온의 몰비와 산소공위로부터 비화학량론적 조성식들을 결정하였다. Mossbauer분광분석결과 A자리에 $Ca^{2+}$ 또는 $Sr^{2+}$ 이온이 치환된 계들과는 달리 $Ba^{2+}$ 이온이 치환된 화합물들은 $FeO_6$와 $FeO_4$ 뿐만 아니라 $FeO_5$이 5배위장이 형성됨을 알 수 있었다. 또한 x = 0.25와 0.50 조성들은 초상자성의 스펙트럼을 보이는데 이는 $Fe^{3+}$ 와 $Fe^{4+}$ 이온간의 강자성 상호작용을 하는 영역을 형성하기 때문이다. 모든 시료의 전기전도도는 반도성 범위에 속한다. 시료는 $O^{2-}$ 이온을 매개로 한 Fe 이온간의 전자전달과정에서 $Fe^{4+}$ 이온은 전자 받게 준위로 작용하기 때문에 $Fe^{4+}$이온이 증가함에 따라 전기전도도의 활성화에너지가 감소된다. A series of samples in the $Nd_{1-x}Ba_xFeO_{3-y}$ system has been prepared by heating the reactants to$1200^{\circ}C$ under an ambient atmosphere, and the solid solutions were identified by X-ray power diffraction analysis. The crystal systems of samples with x = 0.00 and 0.25 were found to be orthorhombic whose local symmetry is similiar to the distorted octahedral with orthoferrite type one, whereas those with x = 0.50 and 0.75 to be the cubic system. Since Fe ions in the solid solutions are a mixed valence state between $Fe^{3+}\;and\;Fe^{4+}$ ions, the nonstoichiometric chemical formulas could be determined from the mole ratio of $Fe^{4+}$ ion and oxygen vacacies. According to the Mossbauer spectroscopic analysis, the presence of 5-coordinated $FeO_5$ was evidenced only in the barium compounds along with $FeO_6,\;and\;FeO_4$, but not in the strontium and calcium compounds. The samples with x = 0.25 and 0.50 show a spectrum of superparamagnetism, which might be due to the formation of a domain of the ferromagnetic interaction between the $Fe^{3+}\;and\;Fe^{4+}$ ions. The electrical conductivities of all samples are within semiconducting range. Since the $Fe^{4+}$ ion acts as an electron acceptor level during the electron transfer between the Fe through intermediate $O^{2-}$ ions, the activation energy of the compounds decreases with the increment of $Fe^{4+}$ content.
중심부 PTT 함량이 PLA/PTT 심초형 복합방사 섬유의 기계적 물성에 미치는 영향
장순호,최익성,김희동,오태환 한국섬유공학회 2023 한국섬유공학회지 Vol.60 No.5
In this study, we investigated the effects of core polytrimethylene terephthalate(PTT) content on the mechanical properties of polylactic acid (PLA)/PTT sheath/core (s/c)bicomponent filaments to optimize sheath/core ratio of the filaments. The moleculardynamics simulation of each homo polymer has been performed to predict the tensilebehaviour of the polymers, respectively. The maximum PTT content was 60 wt%, whichwas the best composition in terms of cross-section uniformity and tensile strength. Thetensile strength of PLA/PTT s/c bicomponent filaments decreased with increasing PTT contentup to 50 wt% and showed the maximum at PTT content of 60wt% compared withhomo PLA filaments. It is attributed that the spinning temperature was adjusted for thehigher melting temperature polymer of PTT, causing decrease in melt viscosity of thesheath PLA. Hence, this leads to a less uniform cross-section for PLA/PTT s/c bicomponentfilaments, having less than 60% of core PTT.
열처리에 따른 나일론 46/6 블렌드 원사의 물성과 결정구조 변화 연구
장순호,오태환,김성훈,Jang, Soon Ho,Oh, Tae Hwan,Kim, Seong Hun 한국섬유공학회 2016 한국섬유공학회지 Vol.53 No.3
In this study, the annealing effects on changes in tensile properties and crystal structure of nylon 46/6 blend filament were investigated and compared with those of nylon 6 filament. The nylon 46/6 blend filament was prepared by mixing nylon 46 chips (polymerized nylon 4, 6 (40 mole%) and nylon 6 (60 mole%)) and nylon 6 chips in the ratio 1:1 by weight. The elongation at break of nylon 46/6 blend filaments decreases with increasing annealing temperature and time. Wide angle X-ray scattering revealed that the crystal structure of nylon 46/6 blend filaments had changed to ${\alpha}$-form at an annealing temperature of $180^{\circ}C$. Changes in the properties and crystal structure of the nylon 46/6 blend filament were more sensitive to annealing conditions than those of nylon 6.