Dielectric Properties in the Pb<SUB>1-3x/2</SUB>La<SUB>x</SUB>[(Mg<SUB>1/3</SUB>Ta<SUB>2/3</SUB>)<SUB>0.66</SUB>Zr<SUB>0.34</SUB>]O<SUB>3</SUB> Systems

Yeon Jung Kim 한국진공학회(ASCT) 2017 Applied Science and Convergence Technology Vol.26 No.4

The dielectric constant and loss of poling/non-poling was measured in the Pb1-3x/2Lax[(Mg1/3Ta2/3)0.66Zr0.34]O3 samples. The addition of La<SUP>3+</SUP> to the Pb1-3x/2Lax[(Mg1/3Ta2/3)0.66Zr0.34]O3 did not cause a large change in grain size. But the addition of La<SUP>3+</SUP> did show transition temperature, which shifted toward low temperature in the Pb[(Mg1/3Ta2/3)Zr]O3 systems. In addition, the dielectric and pyroelectric properties (Ɛ~20000, p~0.03 C/m2K) of this system using La<SUP>3+</SUP> have been greatly improved. Pyroelectrics Pb0.97La0.02(Mg1/3Ta2/3) 0.66Zr0.34]O3 system was found to have a relatively high ferroelectric FOMs (FV~0.035 m<SUP>2</SUP>/C, FD~0.52 × 10<SUP>−4</SUP> Pa<SUP>−1/2</SUP>) at room temperature. Spontaneous polarization showed a value of 0.27~0.35 C/m<SUP>2</SUP> in the composition added to La<SUP>3+</SUP>. The piezoelectric constant (d33=350~490 pC/N) and electromechanical coupling factor (kP=0.25~0.35) are obtained in Pb1-3x/2Lax[(Mg1/3Ta2/3) 0.66Zr0.34]O3 compositions with La3<SUP>+</SUP> dopant.

영가철(Fe⁰)과 UV를 이용한 1,4-dioxane 분해 반응시 철농도의 변화와반응 메커니즘의 연구

손현석(Hyun Seok Son),임종권(Jong Kwon Im),조경덕(Kyung Duk Zoh) 大韓環境工學會 2008 대한환경공학회지 Vol.30 No.3

본 논문은 1,4-dioxane의 분해를 위한 F⁰와 Fe²⁺의 반응에서 UV의 영향을 평가하기 위해 반응 중 [Fe²⁺]와 용액 중 총철이온 농도에 대한 [Fe²⁺]의 비([Fe²⁺]/[Fe(t)])의 변화를 조사하였다. UV, F⁰, 그리고 Fe²⁺의 단독반응에 의한 1,4-dioxane의 분해효율은 10% 이하였으며 그 반응 동안 [Fe²⁺]와 [Fe²⁺]/[Fe(t)]의 변화 또한 거의 일어나지 않았다. 그러나 UV 조사에 의해 F⁰의 산화는 약 25% 정도 증가하였을 뿐만 아니라 1,4-dioxane의 분해 효율 또한 개선되었다. Fenton 반응(Fe²⁺+H₂O₂)의 경우 반응초기 90 분까지는 매우 빠른 분해율을 보인 반면 90분 이후에는 1,4-dioxane의 분해가 거의 정지되었다. Fe²⁺와 UV 반응에서는 [Fe²⁺]/ [Fe(t)]가 반응 시작부터 감소하다가 90분 이후부터 완만한 증가를 보였다. F⁰와 UV 반응의 경우 반응속도 상수는 반응시작 90 분 동안 1.84×10-3 min-1에서 Fe²⁺의 변화가 일어나는 시간인 90분 이후 9.33×10-3 min-1로 큰 상승을 보였고 이 변화는 [Fe²⁺]/ [Fe(t)]이 감소이후에 일어났다. [Fe²⁺]/[Fe(t)]는 Fe²⁺와 UV 반응에서 계속적으로 감소하였다. 그러나 그 반응에 ClO₄-를 첨가한 경우 [Fe²⁺]/[Fe(t)]는 완만한 상승을 보였다. 이 결과들은 1,4-dioxane의 분해는 주로 F⁰이 Fe²⁺로 산화되는 기간이 아닌 Fe²⁺가 Fe³⁺로 산화, 환원되는 반응 동안 일어났음을 보여준다. 즉, 1,4-dioxane의 주요 분해는 철순환에서 생성되는 라디칼에 의한 산화작용이라 할 수 있다. 또한 UV와 ClO₄-는 Fe³⁺의 환원에 큰 작용을 하는 것으로 관찰되었고 이는 radical의 지속적인 생산이라는 측면에서 1,4-dioxane의 분해효율을 증가시키기 위해 매우 중요한 부분이라 할 수 있다. The study presents the results of 1,4-dioxane degradation using zero valent (F⁰) or Fe²⁺ ions with and without UV. During the reaction, the change of [Fe²⁺] and [Fe²⁺]/[Fe(t)], the concentration ratio of ferrous ion to total iron ion in solution was measured. Less than 10% degradation of 1,4-dioxane was observed by UV-only, F⁰-only, and Fe²⁺-only conditions, and also the changes of [Fe²⁺] and [Fe²⁺]/[Fe(t)] were minimal in each reaction. However, the oxidation of F⁰ was enhanced with the irradiation of UV by approximately 25% and the improvement of 1,4-dioxane degradation was observed. Fenton reaction (Fe²⁺+H₂O₂) showed higher degradation efficiency of 1,4-dioxane until 90 min, which of the degradation was stopped after that time. In the reaction of Fe²⁺ and UV, the ratio of [Fe²⁺]/[Fe(t)] decreased then slowly increased after a certain time indicating the reduction of Fe³⁺ to Fe²⁺. In case of F⁰ in the presence of UV, the first-order rate constant was found to be 1.84×10-3 min-1 until 90 min, and then changed to 9.33×10-3 min-1 when the oxidation of Fe²⁺ mainly occurred. In this case [Fe²⁺]/[Fe(t)] kept decreasing for the reaction. However, the addition of perchlortae (ClO₄-) in the reaction of F⁰ and UV induced the continuous increase of [Fe²⁺]/[Fe(t)] ratio. The results mean the primary degradation factor of 1,4-dioxane is the oxidation by the radicals generated from the redox reaction between Fe²⁺ and Fe³⁺. Also, both UV and ClO₄- played the role inducing the reduction of Fe³⁺, which is important to degrade 1,4-dioxane by enhancing the generation of radicals.

Improvement of the Figure of Merit in Pb[(Mg<SUB>1/3</SUB>Ta<SUB>2/3</SUB>)<SUB>0.7</SUB>Ti<SUB>0.3</SUB>]O₃ Systems

Yeon Jung Kim 한국진공학회(ASCT) 2016 Applied Science and Convergence Technology Vol.25 No.5

The Pb[(Mg1/3Ta2/3)0.7Ti0.3]O₃+xwt%PbO systems at temperature of 1250℃ for 4 hours was successful synthesized. In this study, PbO-doped Pb[(Mg1/3Ta2/3)0.7Ti0.3]O₃ systems with non-linear behaviors showed ordering-degree dependence at the low temperature range were prepared using the columbite precursor method. And the characteristic of remnant polarization vs. electric field were analyzed. The pyroelectric, dielectric and piezoelectric properties of partially disordered Pb[(Mg1/3Ta2/3)0.7Ti0.3]O₃+xwt%PbO solid solutions were studied as a function of temperature, frequency, and electric field. It showed distinct features of temperature dependent of pyroelectric coefficient, spontaneous polarization and dielectric constant at about 50℃. The figure of merit was calculated as pyroelectric coefficient, dielectric constant and dissipation factor. It was found that the high voltage responsivity FV, high detectivity FD were 0.0373 ㎡/C and 0.6735×10<SUP>−4</SUP> Pa<SUP>−1/2</SUP>, respectively, in the Pb[(Mg1/3Ta2/3)0.7Ti0.3]O₃+3.0 wt%PbO system.

Characterization and Physical Properties of Ba<SUB>0.9</SUB>Sb<SUB>0.1</SUB>TiO₃ Solid Solution

Yeon Jung Kim 한국진공학회(ASCT) 2019 Applied Science and Convergence Technology Vol.28 No.2

BaTiO₃ is known to be an environmentally friendly electronic material with a phase transition temperature that can be controlled through the substitution of an appropriate additive. Physical changes of grain growth in Ba0.9Sb0.1TiO₃ were analyzed by adding a small amount of antimony to pure BaTiO₃. The Ba0.9Sb0.1TiO₃ solid solution with antimony substitution was prepared under various calcination and sintering conditions. The optimal conditions for sintering were confirmed and the grain growth process was clearly understood. As a result, the relationship between the dielectric properties and the polycrystalline structure of Ba0.9Sb0.1TiO₃ substituted with antimony was confirmed. The maximum dielectric constant of the Ba0.9Sb0.1TiO₃ solid solution was found to exceed about 5500 and the dielectric constant at room temperature reached nearly 4000. The transition temperature of Ba0.9Sb0.1TiO₃ was shifted closer to room temperature than that of pure BaTiO₃. Unlike the phase transition behavior of pure BaTiO₃, the dielectric constant curve, which is a function of temperature for all samples, showed a very gradual change.

Magnetodielectric Effect in Microwave-Sintered Ba<SUB>0.8</SUB>Sr<SUB>0.2</SUB>TiO₃ and Co<SUB>0.9</SUB>Ni<SUB>0.1</SUB>Fe₂O₄ Composite

Sagar M. Mane,Sachin A. Pawar,Dipali S. Patil,Seong Hun Lee,Jae Cheol Shin 한국진공학회(ASCT) 2020 Applied Science and Convergence Technology Vol.29 No.2

Composites constructed by combining ferroelectric and ferromagnetic materials are of significant interest owing to their multifunctional features and potential applications in multifunctional devices. Herein, the magnetodielectric effect of a composite containing ferroelectric Ba0.8Sr0.2TiO₃ (BST) and ferrite Co0.9Ni0.1Fe₂O₄ (CNFO) phases is investigated. This ferroelectric and ferrite composite is synthesized using the co-precipitation method followed by microwave sintering. The tetragonal crystal structure of BST and cubic structure of CNFO are confirmed using X-ray diffraction. All composite samples are characterized using nanoparticle tracking analysis. The measurements of dielectric constant (room temperature) and loss tangent as a function of frequency show an increase in the dielectric constant with an increase in the CNFO phase. The highest value of magnetodielectric coefficient, -40.13 %, is observed for the 60BST-40CNFO composite at 100 Hz, which decreases with an increase in the applied frequency.

Influence of Bismuth Oxide on Dielectric Properties of Barium Titanate Solid Solution

Yeon Jung Kim 한국진공학회(ASCT) 2021 Applied Science and Convergence Technology Vol.30 No.4

A Ba0.9Bi0.1TiO₃ solid solution was prepared by substituting 0.1 mole % Bi₂O₃ at the Ba<SUP>2+</SUP> sites in BaTiO₃, and its dielectric properties were investigated. The Ba0.9Bi0.1TiO₃ solid solution was sintered at 1310 ℃ for 5 h. The stable formation of the perovskite structure was confirmed through X-ray diffraction, energy-dispersive X-ray spectroscopy, and field emission scanning electron microscopy. Unlike pure BaTiO₃, pyrochlore Bi₂Ti₂O7 was observed in Ba0.9Bi0.1TiO₃ at approximately 27.1º. Overall, the perovskite structure was well formed. The Ba0.9Bi0.1TiO₃ solid solution showed typical dielectric properties and followed the modified Curie–Weiss law. In addition, the curve of the dielectric constant vs. temperature showed an extremely gradual change compared to the phase transition behavior of BaTiO₃.

Bi0.5Sb1.5Te3 열전 박막과 전극재료의 접촉저항 측정

전성재(S.-j. Jeon),현승민(H.-J. Lee),이후정(H.-J. Lee),용호(H. Yong) 한국정밀공학회 2013 한국정밀공학회 학술발표대회 논문집 Vol.2013 No.5월

Optical properties of CuGa<SUB>1-x</SUB>In<SUB>x</SUB>Se₂:Co(0.5 wt %) single crystal thin film for solar cell grown hot wall epitaxy method

Hong Kwang-Joon(홍광준),Lee Ki-Jeong(이기정) 한국태양에너지학회 2017 한국태양에너지학회 학술대회논문집 Vol.2017 No.4

고에너지 고밀도 고리탄화수소 화합물의 구조에 따른 물성 연구

조준현(Joonhyun Cho),권태수(Taesoo Kwon),정덕진(Deokjin Jeong),오창호(Changho Oh),박대인(Daein Park),한정식(Jeongsik Han) 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.11

액체 추진기관을 적용하는 무기체계는 용도가 점차 증가되는 추세에 있으며, 운용목적 및 환경에 따라 다양한 물성을 가진 액체연료의 수요도 많아지고 있다. norbornane 또는 dicyclopentane 구조를 포함한 고리탄화수소 화합물은 고밀도 고에너지 특성을 바탕으로 다양한 유도무기체계에 적용되고 있으며, 현재도 많은 분야에서 연구 대상이 되고 있다. 본 연구에서는 분자물질의 설계 및 이를 대상으로 합성한 다양한 고리형 탄화수소화합물의 물성을 분석하여 그 구조에 따라 밀도와 발열량등 이화학 특성이 어떤 경향을 나타내는지 알아보았다. The weapon systems with a liquid propulsion engine have been used for various purposes and demands of the liquid fuel with variety of properties for its operational purposes and environment. The cyclic hydrocarbons including norbornane or dicyclopentane structures have many applications to the guided weapon systems due to the high density and high energy characteristics, also efforts have been given in many fields. In this study, the cyclic hydrocarbons that we designed and fabricated were investigated to obtain tendency on the structures.

Removal of Indoor Tobacco Smoke under Light and Dark Conditions as Affected by Foliage Plants

Jee-Won Yoon(윤지원),Ki-Cheol Son(손기철),Dong Sik Yang(양동식),Stanley J. Kays 한국원예학회 2009 원예과학기술지 Vol.27 No.2

실내식물[스파티필름(Spathiphyllum spp.), 인도고무나무(Ficus elastica), 싱고니움(Syngonium podophyllum)]이 담배연기(ETS)내 미세분진의 제거능에 미치는 영향과 그에 따른 식물의 생리적 반응을 조사하였다. 밀폐 챔버 내 미세분진 농도가 대략 182 ㎍ㆍm⁻³이 되도록 10분 동안 안정화시킨 후 PM10과 1.0, 0.5 ㎛의 감소량을 경시적으로 조사하였다. 빈 챔버내에 주입된 미세분진도 시간이 지남에 따라 흡착과 침강에 의해서 자연적 감소가 발생되었으며, 식물 도입시는 광ㆍ암상태 모두에서 감소율이 훨씬 빨라졌다. 미세분진의 제거율은 광상태에서 식물종에 따라 유의성이 있는 차이가 나타났지만, 엽면적과는 상관관계가 없는 것으로 나타났다. 단위 엽면적으로 비교할 때 3종 중 스파티필름의 제거율이 광ㆍ암상태 모두에서 가장 높았으며, 이 경우 암상태보다는 광상태에서 높았다. 또한 암상태에는 식물 종간 미세분진 제거율 및 호흡율에 별다른 차이가 없었다. 광상태의 미세분진 제거율은 광합성이 높은 종에서 높아, 광합성이 미세분진의 흡수와 같은 능동적 제거에 관여하는 것으로 판단된다. The efficacy of three species of indoor plants (Spathiphyllum spp., Ficus elastica and Syngonium podophyllum) for the removal of environment tobacco smoke (ETS) particulate matter (PM) in the light and dark and changes in physiological responses (photosynthesis, transpiration, respiration) of the plants to ETS was assessed. Cigarette smoke was generated in sealed chambers to give an initial concentration of ~182 ㎍ㆍm⁻³ and after normalization (10 min) the concentrations of various size categories (PM₁₀, PM1.0, and PM0.5) were determined. ETS PM diminished with time due to adsorption and sedimentation. However, the decrease was accelerated by the presence of indoor plants in both the light and dark. Removal efficiency varied among species and was not correlated with leaf area. Spathiphyllum spp. had the highest removal efficacy on a leaf area basis among the species tested in both light and dark conditions, and removal was more efficient in the light than in the dark. In the dark there was little difference in removal efficiency among species or in respiratory rate. The removal efficiency in the light was higher in species with higher photosynthetic rates, suggesting that photosynthesis may be involved in the accelerated removal.