• Current Photovoltaic Research
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• v.3 no.3
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• pp.80-84
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• 2015

We suggest new emitter formation method using solid-phase epitaxy (SPE); solid-phase epitaxy emitter (SEE). This method expect simplification and cost reduction of process compared with furnace process (POCl3 or BBr3). The solid-phase epitaxy emitter (SEE) deposited a-Si:H layer by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) on substrate (c-Si), then thin layer growth solid-phase epitaxy (SPE) using rapid thermal process (RTP). This is possible in various emitter profile formation through dopant gas ($PH_3$) control at deposited a-Si:H layer. We fabricated solar cell to apply solid-phase epitaxy emitter (SEE). Its performance have an effect on crystallinity of phase transition layer (a-Si to c-Si). We confirmed crystallinity of this with a-Si:H layer thickness and annealing temperature by using raman spectroscopy, spectroscopic ellipsometry and transmission electron microscope. The crystallinity is excellent as the thickness of a-Si layer is thin (~50 nm) and annealing temperature is high (<$900^{\circ}C$). We fabricated a 16.7% solid-phase epitaxy emitter (SEE) cell. We anticipate its performance improvement applying thin tunnel oxide (<2nm).

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.360-365
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• 1992

We constructed a photoacoustic cell and dewar in order to investigate the phase transition of the solids. The solid-liquid phase transition of a wood's metal was measured by a temperature controlled photoacoustic apparatus. It showed a good agreement with the reported value of the melting point, 343 K. The phase transiton of the wood's metal has been determined to be the first order transition, existing a latent heat, which is typical in the solid-liquid transition. In addition, a supercooling effect was observed by monitoring the photoacoustic signal as the temperature of the sample was decreased. The experiments have demonstrated the photoacoustic detection is an appropriate method to determine the order of transition in solid samples.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.211-214
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• 2001

The undesirable phase transformation of zirconium dioxide at high temperatures can be eliminated by stabilization of the cubic phase with an addition of a selected alkaline earth or rare-earth oxide. In this paper the ionic conductivity of cubic solid solutions in the stabilized ZrO$_2$ by CaO-Y$_2$O$_3$ system was examined. The higher ionic conductivity appears to be related to lower activation energy rather than to the number of oxygen vacancies dictated by composition. Those compositions of highest conductivity lie close to the cubic-monoclinic solid-solution phase boundary. Conductivity temperature data are presented that indicate a reversible order-disorder transition for Zr$_2$2-Y$_2$O$_3$cubic solid solutions containing 20 and 25 mole % $Y_2$O$_3$.

• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.20-23
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• 1986

A reduced condition for liquid-gas phase transition from the singularity of compressibility is derived using diagrammatic approach and is examined in the hard sphere system. The condition turns out that the Percus-Yevick and the Hyper-Netted-Chain approximation never conceive the idea of phase transition, and explains that the liquid-gas transition does not exist in hard sphere system. The solid-fluid transition is considered on the viewpoint of correlation function and diagrammatic analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.480.1-480.1
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• 2014

In this study, we suggest the new emitter formation applied solid phase epitaxy (SPE) growth process using rapid thermal process (RTP). Preferentially, we describe the SPE growth of intrinsic a-Si thin film through RTP heat treatment by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Phase transition of intrinsic a-Si thin films were taken place under $600^{\circ}C$ for 5 min annealing condition measured by spectroscopic ellipsometer (SE) applied to effective medium approximation (EMA). We confirmed the SPE growth using high resolution transmission electron microscope (HR-TEM) analysis. Similarly, phase transition of P doped a-Si thin films were arisen $700^{\circ}C$ for 1 min, however, crystallinity is lower than intrinsic a-Si thin films. It is referable to the interference of the dopant. Based on this, we fabricated 16.7% solar cell to apply emitter layer formed SPE growth of P doped a-Si thin films using RTP. We considered that is a relative short process time compare to make the phosphorus emitter such as diffusion using furnace. Also, it is causing process simplification that can be omitted phosphorus silicate glass (PSG) removal and edge isolation process.

• Elastomers and Composites
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• v.56 no.2
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• pp.72-78
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• 2021

A phase-change material (PCM) is a material that has the ability to delay heat transfer by absorbing heat from its environment or releasing heat to its environment while its phase changes from solid to liquid or liquid to solid at a specific temperature. As it is applied, it can contribute to environmental conservation such as energy savings and carbon dioxide emission reduction. In order for a PCM to store and release heat, the volume change during its phase transition should be large, and thus a phase transition space is required. When a PCM is used as a polymer additive, it is confined within the polymer, and there is no phase transition space; thus, its ability to absorb and release heat is significantly reduced. Therefore, in this study, porous silica was used to provide EVA/PCM compounds with sufficient space for their phase transition, and to improve the compatibility between the EVA and PCM, modified silica is used: surface-modified 5 wt% silica with 3-methacryloxypropyltrimethoxysilane. The compound was prepared and compared with the silica compound. The presence or absence of the modified silica surface modification was confirmed using Fourier-transform infrared spectroscopy and thermogravimetric analysis, the heat capacity of the compound was evaluated based on a differential scanning calorimetry analysis, and its mechanical strength and morphology were determined using scanning electron microscopy.

• Korean Journal of Materials Research
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• v.30 no.9
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• pp.480-488
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• 2020

The electrocaloric effect can be observed in pyroelectric materials based on conversion between electrical and thermal energy, and can be utilized for the future environment-friendly refrigeration technology. Especially, a strong electrocaloric effect is expected in materials in which field-induced phase transition can be achieved. Emerging fluorite-structure ferroelectrics such as doped hafnia and zirconia, first discovered in 2011, are considered the most promising materials for next-generation semiconductor devices. Besides application of fluorite-structure ferroelectrics for semiconductor devices based on their scalability and CMOS-compatibility, field-induced phase transition has been suggested as another interesting phenomenon for various energy-related applications such as solid-state cooling with electrocaloric effect as well as energy conversion/storage and IR/piezoelectric sensors. Especially, their giant electrocaloric effect is considered promising for solid-state-cooling. However, the electrocaloric effect of fluorite-structure oxides based on field-induced phase transition has not been reviewed to date. In this review, therefore, the electrocaloric effect accompanied by field-induced phase transition in fluorite-structure ferroelectrics is comprehensively reviewed from fundamentals to potential applications.

• Tribology and Lubricants
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• v.11 no.4
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• pp.21-27
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• 1995

The effects of interface boundary strength on wear and wear transition during sliding have been investigated in silicon carbide ceramics. Three different microstructures, i.e., solid state sintered silicon carbide, liquid phase sintered silicon carbide and liquid phase sintered silicon carbide composite reinforced with TiB$_{2}$ particulates, were designed by hot pressing. Examinations of crack patterns and fracture modes indicated that interface boundaries were relatively strong between silicon carbide grains in the solid state sintered silicon carbide, intermediate in the liquid phase sintered silicon carbide and weak between silicon carbide grains and TiB$_{2}$ particles in the composite. Wear data and examinations of worn surfaces revealed that the wear behavior of these silicon carbide ceramics could be significantly affected by the interface strength. In the solid state sintered silicon carbide, the wear occurred by a grooving process. In the liquid phase sintered silicon carbide and composite, on the other hand, an abrupt transition in wear mechanism from initial grooving to grain pull-out process occurred during the test. The transition occurred significantly earlier in the composite than in the carbide.

• Bulletin of the Korean Chemical Society
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• v.28 no.1
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• pp.108-114
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• 2007

The lyotropic behaviors to form the structure of distearoylphosphatidylcholine (DSPC)-based liquid crystal (LC) hydrated by only propylene glycol (PG) without water were examined by differential scanning calorimetry (DSC), X-ray diffractions (XRD), polarized microscope (PM) and transmission electron microscope (TEM). By increasing the amount of PG instead of water, it showed the phase transition to be gradually changed from anisotropic structures to other structures more close to isotropic ones and their appearance to be changed from solid-like states to liquid-like ones with more fluidity. Below 50% w/w PG, the mixtures of DSPC and PG resulted in no direct observation of LC structure through PM because they were very close to solid-states. From 55% w/w to 90% w/w of PG, the dense lamella crystalline structures were observed through PM, and their thickness and area decreased as the content of PG increased. Measured by DSC with heating process, the main phase transition from α -lamella phase to isotropic phase appeared from 52.89 °C to 47.41 °C to show linearly decreasing behaviors because PG affects the hydrophobic region of DSPC-based lamella phase. The repeating distance of the lamella phase and the interlayer distance between bilayers were calculated with XRDs and the average number of bilayers related to the thickness in LC structure was approximately estimated by combining with TEM results. The WAXS and DSC measurements showed that all of PG molecules contributed to swelling both the lipid layer in the edge region of lamella phase close to phosphate groups and the interlayer between bilayers below 90% w/w of PG. The phase and thermal behaviors were found to depend on the amount of PG used by means of dissolving DSPC as a phospholipid and rearranging its structure. Instead of water, the inducement of PG as a polar solvent in solid-lamella phase is discussed in terms of the swelling effect of PG for DSPC-based lamella membrane.

• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.586-592
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• 1987

The role of the strain energy and phase stability in the diffuse phase transition have been investigated in the highly disordered solid solution, (Pb1-xBax)(Zr0.4Ti0.6)O3 (0.2 x 0.4). X-ray diffraction analysis indicates that tetragonality (c/a) decreases with the increasing Ba content. Also as the Ba content increases, phase transition becomes more diffuse and at the same time dielectric relaxation as a function of measured frequencies in the 1KHz-10MHz range occurs very pronouncedly. In the Ba content range, 0.2 x 0.35, hysteresis loops are routinely observed and the loop is observed to narrow shape as the Ba content increases but becomes very slim at 40mol% Ba content. Moreover thermal analysis shows that there is no abrupt change in the thermal expansion coefficient below the apparent transition temperature at which dielectric constant becomes maximum. From the above results, it has been concluded that creation of the strain energy due to the distorthion that occurred during the phase transition suppresses diffuse phase transition.