• 제목/요약/키워드: Solid State

검색결과 3,450건 처리시간 0.032초

Influence of Ga Content on the Ionic Conductivity of Li1+XGaXTi2-X(PO4)3 Solid-State Electrolyte Synthesized by the Sol-Gel Method

  • Seong-Jin Cho;Jeong-Hwan Song
    • 한국재료학회지
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    • 제34권4호
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    • pp.185-193
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    • 2024
  • In this study, NASICON-type Li1+XGaXTi2-X(PO4)3 (x = 0.1, 0.3 and 0.4) solid-state electrolytes for all-solid-state batteries were synthesized through the sol-gel method. In addition, the influence on the ion conductivity of solid-state electrolytes when partially substituted for Ti4+ (0.61Å) site to Ga3+ (0.62Å) of trivalent cations was investigated. The obtained precursor was heat treated at 450 ℃, and a single crystalline phase of Li1+XGaXTi2-X(PO4)3 systems was obtained at a calcination temperature above 650 ℃. Additionally, the calcinated powders were pelletized and sintered at temperatures from 800 ℃ to 1,000 ℃ at 100 ℃ intervals. The synthesized powder and sintered bodies of Li1+XGaXTi2-X(PO4)3 were characterized using TG-DTA, XRD, XPS and FE-SEM. The ionic conduction properties as solid-state electrolytes were investigated by AC impedance. As a result, Li1+XGaXTi2-X(PO4)3 was successfully produced in all cases. However, a GaPO4 impurity was formed due to the high sintering temperatures and high Ga content. The crystallinity of Li1+XGaXTi2-X(PO4)3 increased with the sintering temperature as evidenced by FE-SEM observations, which demonstrated that the edges of the larger cube-shaped grains become sharper with increases in the sintering temperature. In samples with high sintering temperatures at 1,000 ℃ and high Ga content above 0.3, coarsening of grains occurred. This resulted in the formation of many grain boundaries, leading to low sinterability. These two factors, the impurity and grain boundary, have an enormous impact on the properties of Li1+XGaXTi2-X(PO4)3. The Li1.3Ga0.3Ti1.7(PO4)3 pellet sintered at 900 ℃ was denser than those sintered at other conditions, showing the highest total ion conductivity of 7.66 × 10-5 S/cm at room temperature. The total activation energy of Li-ion transport for the Li1.3Ga0.3Ti1.7(PO4)3 solid-state electrolyte was estimated to be as low as 0.36 eV. Although the Li1+XGaXTi2-X(PO4)3 sintered at 1,000 ℃ had a relatively high apparent density, it had less total ionic conductivity due to an increase in the grain-boundary resistance with coarse grains.

Fabrication of Flexible Solid-state Dye-sensitized $TiO_2$ Nanotube Solar Cell Using UV-curable NOA

  • 박익재;박상백;김주성;진경석;홍국선
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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    • pp.396-396
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    • 2012
  • $TiO_2$ anatase nanotube arrays (NTAs) were grown by electrochemical anodization and followed annealing of Ti foil. Ethylene glycol/$NH_4F$-based organic electrolyte was used for electrolyte solution and using second anodization process to obtain free-standing NTAs. After obtaining NTAs, ITO film was deposited by sputtering process on bottom of NTAs. UV-curable NOA was used for attach free-standing NTAs on flexible plastic substrate (PEN). Solid state electrolyte (spiro-OMeTAD) was coated via spin-coating method on top of attached NTAs. Ag was deposited as a counter electrode. Under AM 1.5 simulated sunlight, optical characteristics of devices were investigated. In order to use flexible polymer substrate, processes have to be conducted at low temperature. In case of $TiO_2$ nano particles (NPs), however, crystallization of NPs at high temperature above $450^{\circ}C$ is required. Because NTAs were conducted high temperature annealing process before NTAs transfer to PEN, it is favorable for using PEN as flexible substrate. Fabricated flexible solid-state DSSCs make possible the preventing of liquid electrolyte corrosion and leakage, various application.

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Structural and Magnetic Properties of Ni0.6Zn0.4Fe2O4 Ferrite Prepared by Solid State Reaction and Sol-gel

  • Kwon, Yoon Mi;Lee, Min-Young;Mustaqima, Millaty;Liu, Chunli;Lee, Bo Wha
    • Journal of Magnetics
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    • 제19권1호
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    • pp.64-67
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    • 2014
  • $Ni_{0.6}Zn_{0.4}Fe_2O_4$ prepared using solid state reaction and sol-gel methods were compared for their structural and magnetic properties. Due to the much higher annealing temperature used in solid state reaction, the crystalline size was much larger than that of the nanoparticles prepared by sol-gel. The saturation magnetization of sol-gel nanoparticles was higher, and the coercivity was about 2 times larger, compared to the solid state reaction sample. By analyzing the integration intensity of x-ray diffraction peaks (220) and (222), we proposed that the difference in the saturation magnetization might be due to the inversion of cation distribution caused by the different preparation techniques used.

연료전지 UAV를 위한 고체 상태 NaBH4 수소 발생 및 공급 시스템의 특성 연구 (The study on characteristics of solid-state NaBH4 hydrogen generation and supply system for fuel cell UAV)

  • 이충준;김태규
    • 한국항공우주학회지
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    • 제40권10호
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    • pp.901-909
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    • 2012
  • 본 논문은 연료전지 UAV를 위한 고체 상태의 $NaBH_4$ 수소 발생 및 공급 시스템의 특성에 대해 기술하고 있다. 산을 이용하여 $NaBH_4$를 분해할 경우, 발생된 수소의 유량과 압력은 급격히 변화하게 된다. 공급 수소는 자체 가압식 반응기로 안정화 되었고, 수소의 안정화 방법에 대해 소개하였다. 영하조건에서 수소를 발생시키기 위해 묽은 염산을 프로필렌 글리콜 혼합 용액으로 희석하였다. 고체 상태 $NaBH_4$ 수소 발생 및 공급 시스템을 설계하였다. 수소 발생 시스템의 특성을 밝혀내기 위한 기본 구동 실험을 수행하였다.

A Novel Route to Realise High Degree of Graphitization in Carbon-carbon Composites Derived from Hard Carbons

  • Mathur, R.B.;Bahl, O.P.;Dhami, T.L.;Chauhan, S.K.
    • Carbon letters
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    • 제4권3호
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    • pp.111-116
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    • 2003
  • Carbon/carbon composites were developed using PAN based carbon fibres and phenolic resin as matrix in different volume fractions and heat treated to temperatures between $1000^{\circ}C$ to $2500^{\circ}C$. Although both the starting precursors are nongraphitizing hard carbons individually, their composites lead to very interesting properties e.g. x-ray diffractograms show the development of graphitic phase for composites having fibre volume fractions of 30~40%. Consequently the electrical resistivity of such composites reaches a value of $0.8\;m{\Omega}cm$, very close to highly graphitic material. However, it was found that by increasing the fibre volume fraction to 50~60%, the trend is reversed. Optical microscopy of the composites also reveals the development of strong columnar type microstructure at the fibre (matrix interface due to stress graphitization of the matrix. The study forcasts a unique possibility of producing high thermal conductivity carbon/carbon composites starting with carbon fibres in the chopped form only.

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Synthesis of $Cu_2ZnSnSe_4$ compound by solid state reaction using elemental powders

  • Wibowo, Rachmat Adhi;Alfaruqi, Muhammad H.;Jung, Woon-Hwa;Kim, Kyoo-Ho
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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    • pp.134-137
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    • 2009
  • Commercially available elemental powders of Cu, Zn, Sn and Se were employed for crystallizing a stannite-type $Cu_2ZnSnSe_4$ compound by means of solid state reaction. $Cu_2ZnSnSe_4$ reaction chemistry was also modeled based on differential-thermal analysis and X-ray powder diffraction results. It was observed that Se tends to react preferably with Cu to form CuSe and $CuSe_2$ phases at low reaction temperature. The formation of $Cu_5Zn_8$ intermetallic phase was found to be the intermediate reaction path for the binary ZnSe formation. A solid state reaction at $320^{\circ}C$ reacted elemental powderst obinary selenides of CuSe, ZnSe and SnSe completely. The crystallization of $Cu_2ZnSnSe_4$ was was detected to begin at $300^{\circ}C$ and its weight fraction increased with an increase of reaction temperature, which most probably formed from the reaction between $Cu_2SnSe_3$ and ZnSe.

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정책변수를 고려한 확산모형의 연구 - 고체조명(Solid-State Lighting : SSL) 기술을 중심으로 (A Technology Diffusion Model Based on Technology Policy: The Case of Solid-State Lighting Technology Diffusion in the U.S.)

  • 진메이웨
    • 한국산학기술학회논문지
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    • 제12권6호
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    • pp.2522-2527
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    • 2011
  • 기술정책은 신기술 확산에 영향을 주는 중요한 요인 중의 하나이다. 본 연구의 목적은 기존의 전염병 확산 모형을 기초로 정책변수를 추가한 신기술 확산모형을 구축하고, 미국에서의 이산화탄소 배출 감소에 응용되는 고체조명(Solid-State Lighting) 기술을 사례로 실증연구를 진행하는 것이다. 실험결과, 정책변수는 정(+)의 영향을 미치는 것으로 나타났으며, 기술정책은 신기술의 확산에 추진 작용을 하는 것으로 나타났다. 이는 정책적 역할에 대한 정량적 이해를 도모하는데 있어서 정량적 판단을 위한 자료를 제공하고, 정책변수와 신기술 확산의 정량적 관계를 파악하는 데 도움이 될 것이다.

Solid State Drive(SSD)에 대한 가속열화시험 데이터 모델링 및 분석 (Modeling and Analysis of Accelerated Degradation Testing Data for a Solid State Drive (SSD))

  • 문병민;최영진;지유민;이용중;이근우;나한주;양중섭;배석주
    • 한국신뢰성학회지:신뢰성응용연구
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    • 제18권1호
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    • pp.33-39
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    • 2018
  • Purpose: Accelerated degradation tests can be effective in assessing product reliability when degradation leading to failure can be observed. This article proposes an accelerated degradation test model for highly reliable solid state drives (SSDs). Methods: We suggest a nonlinear mixed-effects (NLME) model to degradation data for SSDs. A Monte Carlo simulation is used to estimate lifetime distribution in accelerated degradation testing data. This simulation is performed by generating random samples from the assumed NLME model. Conclusion: We apply the proposed method to degradation data collected from SSDs. The derived power model is shown to be much better at fitting the degradation data than other existing models. Finally, the Monte Carlo simulation based on the NLME model provides reasonable results in lifetime estimation.

Synthesis and Electrochemical Properties of Nanocrystalline LiFePO4 Obtained by Different Methods

  • Son, C.G.;Chang, D.R.;Kim, H.S.;Lee, Y.S.
    • Journal of Electrochemical Science and Technology
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    • 제2권2호
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    • pp.103-109
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    • 2011
  • Nanocrystalline $LiFePO_4$ powders were prepared at 660-$670^{\circ}C$ in an Ar atmosphere using two different synthetic routes, solid-state and sol-gel. Both materials showed well-developed XRD patterns without any impurity peaks. Particles composed in the range of 200-300 nm from the solid-state method, and 50-100 nm from the sol-gel method, were confirmed through scanning electron microscopy and dynamic light scattering. The $LiFePO_4$ obtained by the sol-gel method offered a high discharge capacity (153 mAh/g) and stable discharge behavior, even at elevated temperatures (50 and $60^{\circ}C$), whereas poor electrochemical performance was observed from the solid-state method. Rate capability studies for sol gel-derived $LiFePO_4$ ranged from 0.2 to 30 C, which revealed excellent retention over 70 cycles with a 99.9% capacity.

Variable Temperature High-Resolution 19F MAS Solid-State NMR Characterization of Fluorocarbon Rubbers

  • Park, Tae-Joon;Choi, Sung-Sub;Kim, Ji-Sun;Kim, Yong-Ae
    • Bulletin of the Korean Chemical Society
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    • 제32권7호
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    • pp.2345-2350
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    • 2011
  • Variable temperature high-resolution $^{19}F$ magic angle spinning (MAS) solid-state NMR spectroscopy was used to characterize fluorocarbon (FKM) rubbers. The high-resolution spectra of copolymers made from two monomers, vinylidene fluoride and hexafluoropropene, and terpolymers composed of vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene, were obtained using MAS speeds of up to 18 kHz combined with high temperatures of up to 200 $^{\circ}C$ at a magnetic field strength of 9.4 Tesla. From these high resolution solid-state NMR spectra, we were able to assign the spectral peaks and differentiate the copolymer FKM from the terpolymer FKM. We also determined quantitatively the monomer compositions of each FKM rubber.