• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.4
• /
• pp.599-604
• /
• 1998

We have investigated Pt and $RuO_2$ as a bottom electrode for ferroelectric capacitor applications. The bottom electrodes were prepared by using an RF magnetron sputtering method. Some of the investigated parameters were a substrate temperature, gas flow rate, RF power for the film growth, and post annealing effect. The substrate temperature strongly influenced the surface morphology and resistivity of the bottom electrodes as well as the film crystallographic structure. XRD results on Pt films showed a mixed phase of (111) and (200) peak for the substrate temperature ranged from RT to $200^{\circ}C$, and a preferred (111) orientation for $300^{\circ}C$. From the XRD and AFM results, we recommend the substrate temperature of $300^{\circ}C$ and RF power 80W for the Pt bottom electrode growth. With the variation of an oxygen partial pressure from 0 to 50%, we learned that only Ru metal was grown with 0~5% of $O_2$ gas, mixed phase of Ru and $RuO_2$ for $O_ 2$ partial pressure between 10~40%, and a pure $RuO_2$ phase with $O_2$ partial pressure of 50%. This result indicates that a double layer of $RuO_2/Ru$ can be grown in a process with the modulation of gas flow rate. Double layer structure is expected to reduce the fatigue problem while keeping a low electrical resistivity. As post anneal temperature was increased from RT to $700^{\circ}C$, the resistivity of Pt and $RuO_2$ was decreased linearly. This paper presents the optimized process conditions of the bottom electrodes for memory device applications.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.12
• /
• pp.1249-1256
• /
• 2005

This study was performed to investigate the efficiency of the corrosion prevention in the simulated distribution system using CCPP(Calcium Carbonate Precipitation Potential) as the anti-corrosive index by adjusting pH, total dissolved solids, alkalinity and calcium hardness in the water treatment pilot process. The materials of the simulated distribution system(SDS) were equiped with same materials of real field water distribution system. CCPP concentrations controlled by $Ca(OH)_2$, $CO_2$ gas and $Na_2CO_3$ in the simulated distribution system and uncontrolled by the chemicals in the general water distribution system were average 0.61 mg/L and -7.77 mg/L. The concentrations of heavy metals like Fe, Zn, Cu ions in effluent water of the simulated distribution system controlled with water quality were decreased rather than the general water distribution system uncontrolled with water quality. In simulated distribution system(SDS), corrosion prevention film formed by CCPP control was observed that scale was come into forming six months later and it was formed into density as time goes on. We were analyzed XRD(X-ray diffraction) for investigating component of crystal compounds and structure for galvanized steel pipe(15 mm). Finding on analysis, scale was compounded to $Zn_4CO_3(OH)_6{\cdot}H_2O$ (Zinc Carbonate Hydroxide Hydrate) after ten months late, and it was compounded on $CaCO_3$(Calcium Carbonate) and $ZnCO_3$(Smithsonite) after nineteen months later.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.14 no.1
• /
• pp.35-42
• /
• 2008

Twenty eight gas impermeable plastic films for food-contact application were collected in the domestic market and material and/or migration tests for overall migration, antioxidants, potassium permanganate consumption, heavy metal, and plasticizers were carried out. The average overall migration values for NY/PE or NY/LLDPE, PETP/PE, and PVDC packaging films obtained by using n-heptane as fatty food simulant were 7.6, 6.9 and 14.1 mg/L, respectively. These values were much lower than the limit values of 150 and 30 mg/L for polyethylene and polyvinylidene chloride prescribed in the Korea Food Code. In almost of the packaging materials tested, the antioxidants such as Irganox 1010, Irganox 1076 and Irgafos 168 were found. The migration test result showed that almost of all samples except PVDC film contained Irganox 1076 and Irgafos 168, while the maximum migration value of Irganox 1076 into n-heptane was found in the Ny/PE/LLDPE(15/25/50 ${\mu}m$) sample at the concentration of 216.9 ${\mu}g/g$. From the plastic packaging samples tested, plasticizers such as DEP, DPRP, DBP, DPP, BBP, DCHP, DEHP, DEHA and observed above the detection limit. Consumption amount of potassium permanganate was much lower than the limit value of 10 mg/L. In the material test for heavy metals, cadmium and lead were determined at the concentrations far below the limit value of 100 mg/kg. The migration test for cadmium and lead showed a lower value than the detection limit. Therefore, it can be concluded that the safety status of the plastic films tested met the requirement of limit values as prescribed for the material and migration tests of food packaging utensils, containers and packages of the Korea Food Code.

• Radiation Oncology Journal
• /
• v.19 no.1
• /
• pp.74-80
• /
• 2001

Purpose : Irradiation cones by using backscatter electrons are made for the treatment of superficial small lesions of skin, oral cavity, and rectum where a significant dose gradient and maximum surface dose is desired. Methods and Materials : Backscatter electrons are produced from the primary electron beams from the linear accelerators. The design consists of a cylindrical cone that has a thick circular plate of high atomic number medium (Pb or Cu) attached to the distal end, and the plate can be adjusted the reflected angle. Primary electrons strike the metal plate perpendicularly and produce backscatter electrons that reflect through the lateral hole for treatment. Using film and a parallel plate ion chamber, backscatter electron dose characteristics are measured. Results : The depth dose characteristic of the backscatter electron is very similar to that of the hard x-ray beam that is commonly used for the intracavitary and superficial lesions. The basckscatter electron energy is nearly constant and effectively about 1.5 MeV from the clinical megavoltage beams. The backscatter electron dose rate of $35\~85\;cGy/min$ could be achieved from modern accelerators without any modification. and the depth in water of $50\%$ depth dose from backscatter electron located at 6mm for $45^{\circ}$ angled lead scatter. The beam flatness is dependent on the slit size and the depth of treatment, but is satisfactory to treat small lesions. Conclusions : The measured data for backscatter electron energy, depth dose flatness dose rate and absolute dose indicates that the backscatter electrons are suitable for clinical use.

• Journal of the Korean Magnetics Society
• /
• v.16 no.1
• /
• pp.23-27
• /
• 2006

By substituting Mn or Cr for Co in inverse spinel $CoFe_2O_4,\;Mn_xCo_{1-x}Fe_2O_4\;and\;Cr_xCo_{1-x}Fe_2O_4$ and thin films were prepared by sol-gel method and their structural and magnetic properties were investigated. X-ray diffraction indicates that the cubic lattice constant increase for the Mn substitution while it hardly changes for the Cr substitution. Substitution of $Mn^{2+}$ for octahedral $Co^{2+}$ sites can explain the increase of lattice constant in $Mn_xCo_{1-x}Fe_2O_4$. On the other hand, Substitution of $Cr^{3+}$ for octahedral $Co^{2+}$ and subsequent reduction of $Fe^{3+}$ ion into $Fe^{2+}$ are expected to happen. Mossbauer spectroscopy measurements on $Cr_xCo_{1-x}Fe_2P_4$ indicate the existence of tetrahedral $Fe^{2+}$ ions that are created through reduction of tetrahedral $Fe^{3+}$ ions in order to compensate charge imbalance happened by $Cr^{3+}$ substitution for octahedral $Co^{2+}$ sites. On the other hand, no $Fe^{2+}$ ions were detected by Mossbauer spectroscopy for $Mn_xCo_{1-x}Fe_2O_4$. A migration of $Fe^{3+}$ ions from octahedral to tetrahedral sites In $Mn_xCo_{1-x}Fe_2O_4$ was detected by Mossbauer spectroscopy for x>0.47. Vibrating sample magnetometry measurements on the samples at room temperature revealed that the saturation magnetization increases by Mn and Cr substitution for certain range of x, qualitatively explainable in terms of the comparison of spin magnetic moment among the related transition-metal ions.

• Journal of the Korean Electrochemical Society
• /
• v.13 no.2
• /
• pp.116-122
• /
• 2010

A $Cu_3Si$ film electrode is obtained by Si deposition on a Cu foil using DC magnetron sputtering, which is followed by annealing at $800^{\circ}C$ for 10 h. The Si component in $Cu_3Si$ is inactive for lithiation at ambient temperature. The linear sweep thermammetry (LSTA) and galvano-static charge/discharge cycling, however, consistently illustrate that $Cu_3Si$ becomes active for the conversion-type lithiation reaction at elevated temperatures (> $85^{\circ}C$). The $Cu_3Si$ electrode that is short-circuited with Li metal for one week is converted to a mixture of $Li_{21}Si_5$ and metallic Cu, implying that the Li-Si alloy phase generated at 0.0 V (vs. Li/$Li^+$) at the quasi-equilibrium condition is the most Li-rich $Li_{21}Si_5$. However, the lithiation is not extended to this phase in the constant-current charging (transient or dynamic condition). Upon de-lithiation, the metallic Cu and Si react to be restored back to $Cu_3Si$. The $Cu_3Si$ electrode shows a better cycle performance than an amorphous Si electrode at $120^{\circ}C$, which can be ascribed to the favorable roles provided by the Cu component in $Cu_3Si$. The inactive element (Cu) plays as a buffer against the volume change of Si component, which can minimize the electrode failure by suppressing the detachment of Si from the Cu substrate.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.4
• /
• pp.83-89
• /
• 2020

For the past few decades, as part of efforts to protect the environment where fossil fuels, which have been a key energy resource for mankind, are becoming increasingly depleted and pollution due to industrial development, ecofriendly secondary batteries, hydrogen generating energy devices, energy storage systems, and many other new energy technologies are being developed. Among them, the lithium-ion battery (LIB) is considered to be a next-generation energy device suitable for application as a large-capacity battery and capable of industrial application due to its high energy density and long lifespan. However, considering the growing battery market such as eco-friendly electric vehicles and drones, it is expected that a large amount of battery waste will spill out from some point due to the end of life. In order to prepare for this situation, development of a process for recovering lithium and various valuable metals from waste batteries is required, and at the same time, a plan to recycle them is socially required. In this study, we introduce a nanoscale pattern transfer printing (NTP) process of Li2CO3, a representative anode material for lithium ion batteries, one of the strategic materials for recycling waste batteries. First, Li2CO3 powder was formed by pressing in a vacuum, and a 3-inch sputter target for very pure Li2CO3 thin film deposition was successfully produced through high-temperature sintering. The target was mounted on a sputtering device, and a well-ordered Li2CO3 line pattern with a width of 250 nm was successfully obtained on the Si substrate using the NTP process. In addition, based on the nTP method, the periodic Li2CO3 line patterns were formed on the surfaces of metal, glass, flexible polymer substrates, and even curved goggles. These results are expected to be applied to the thin films of various functional materials used in battery devices in the future, and is also expected to be particularly helpful in improving the performance of lithium-ion battery devices on various substrates.