• Carbon letters
• /
• 제26권
• /
• pp.61-65
• /
• 2018

Comprehensive calculations of the Rh decoration effect on zigzag CNTs with n ranging from 7 to 12 were conducted in this work to understand the effect of Rh doping on geometric structures and electronic behaviors upon metallic and semiconducting CNTs. The obtained results indicated that Rh dopant not only contributes to the deformation of C-C bonds on the sidewall of CNTs, but also transforms the electron distribution of related complexes, thereby leading to a remarkable increase of the conductivity of pure CNTs given the emerged novel state within the energy gap for metallic CNTs and the narrowed energy gap for semiconducting CNTs. Our calculations will be meaningful for exploiting novel CNT-based materials with better sensitivity to electrons and higher electrical conductivity compared with pure CNTs.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 추계학술발표대회
• /
• pp.3.1-3.1
• /
• 2011

Nanoengineered materials with advanced architectures are critical building blocks to modulate conventional material properties or amplify interface behavior for enhanced device performance. While several techniques exist for creating one dimensional heterostructures, electrospinning has emerged as a versatile, scalable, and cost-effective method to synthesize ultra-long nanofibers with controlled diameter (a few nanometres to several micrometres) and composition. In addition, different morphologies (e.g., nano-webs, beaded or smooth cylindrical fibers, and nanoribbons) and structures (e.g., core-.shell, hollow, branched, helical and porous structures) can be readily obtained by controlling different processing parameters. Although various nanofibers including polymers, carbon, ceramics and metals have been synthesized using direct electrospinning or through post-spinning processes, limited works were reported on the compound semiconducting nanofibers because of incompatibility of precursors. In this work, we combined electrospinning and galvanic displacement reaction to demonstrate cost-effective high throughput fabrication of ultra-long hollow semiconducting chalcogen and chalcogenide nanofibers. This procedure exploits electrospinning to fabricate ultra-long sacrificial nanofibers with controlled dimensions, morphology, and crystal structures, providing a large material database to tune electrode potentials, thereby imparting control over the composition and shape of the nanostructures that evolved during galvanic displacement reaction.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
• /
• pp.19-19
• /
• 2003

The injection of spins into nonmagnetic semiconductors has recently attracted great interest due to the potential to create new classes of spin-dependent electronic devices. A recent strategy to achieve control over the spin degree of freedom is based on dilute ferromagnetic semiconductors. Ferromagnetism has been reported in various semiconductor groups including II-Ⅵ, III-V, IV and II-IV,-V$_2$, which will be reviewed. On the other hand, to date the low solubility of magnetic ions in non-magnetic semiconductor hosts and/or low Curie temperature have limited the opportunities. Therefore the search for other promising ferromagnetic semiconducting materials, with high magnetic moments and high Curie temperatures (Tc), is of the utmost importance. In this talk, we also introduce new pure ferromagnetic semiconductors, MnGeP$_2$ and MnGeAs$_2$, exhibiting ferromagnetism and a magnetic moment per Mn at 5K larger than 2.40 ${\mu}$B. The calculated electronic structures using the FLAPW method show an indirect energy gap of 0.24 and 0.06 eV, respectively. We have observed spin injection in MnGeP$_2$ and MnGeAs$_2$ magnetic tunnel junctions through semiconducting barriers.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.74-75
• /
• 2006

In organic opto-electronic applications, such as light emitting diodes (LEDs) and photovoltaic devices (PVDs), the morphology of the active layer is of crucial importance. To control the morphology of the active layer the self-assembling properties of block copolymers was used. Several rod-coil semiconducting diblock copolymers consisting of a conjugated block and a second coil block functionalized with electron transporting and/or accepting materials (such as $C_{60}$) were synthesized. The conjugated block acting as light absorbing, electron donating and hole transporting material. The donor/acceptor photovoltaic devices performance with active layer the above mentioned semiconducting block copolymers will be presented.

• 한국세라믹학회지
• /
• 제28권7호
• /
• pp.525-530
• /
• 1991

The effects of 0.15mol% Y2O3 doped semiconducting (Ba1-xPbx)TiO3 ceramics with 0.5 mol% Pb5Ge3O11 as sintering additives have been investigated as function of Pb contents (from 0.05 mol to 0.3 mol) and sintering temperatures (from 1050$^{\circ}C$ to 1200$^{\circ}C$). As the Pb content increases in the (Ba1-xPbx)TiO3 system, the size and resistance of the grain increase but the capacitance of the grain boundary decreases due to the formation of liquid phase during the sintering. And with increasing the sintering temperatures, the resistance of the grain decreases but the capacitance of the grain boundary increases. The PTCR effects decrease with increasing the Pb content and the sintering temperature.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 D
• /
• pp.1475-1477
• /
• 1998

In this paper, breakdown strength and time to breakdown are experimented under semiconducting layer/needle electrode in XLPE which is used for power cable insulator. Shape and scale parameters of obtained data are estimated using 2-parameters Weibull distribution. Life-time coefficient(n-value) using shape parameters for breakdown strength and time to breakdown tests is estimated. n-value of 1000 hour aged XLPE showed higher value than that of virgin XLPE. Increase of n-value is estimated by the stability due to removal of by-product and residue gas in XLPE by heating.

• 한국세라믹학회지
• /
• 제33권11호
• /
• pp.1231-1236
• /
• 1996

The electrode resistance of semiconducting PTC BaTiO3 ceramic material was studied in some detail. Comme-rical In-Ag paste In-Ga alloy and electroless plated Ni as well as evaporated Al were chosen as electrode. The contact resistance of electroded samples were measured by both dc resistivity and ac impedance analysis. The aging effect on contact resistance under cyclic loading from -1$0^{\circ}C$ to 85$^{\circ}C$ was also monitored for the prolonged period of time. In case of Al electroded samples the heat treatment and protective coating had effects on the stability against contact resistance degradation. It was also found that the samples with commercial In-Ag paste and electroless plated Ni electrode had good properties of contact resistance against aging.

• 한국세라믹학회지
• /
• 제26권1호
• /
• pp.73-80
• /
• 1989

Preparation and characteristics of electroless Ni-P and Ni-B systems for semiconducting ceramics have been investigated as a function of deposit rate, reducing agent and pH variation. The effect of DMAB as ruducing agent is greater than that of sodium hypophosphite. The nickel electrode prepared from the nickel-phosphorus system with sodium hypophosphite shows low contact resistance of 0.99ohm compared with the resistance of 10chm in the electrode prepared from the nickel-boron system with DMAB. The contact resistance increases with increasing pH valuein the nickel-phosphorus system with sodium hypophosphite. The ratio of Ni to P is about 76.0/24.0 for the contact resistance of 0.99ohm in the above system.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 C
• /
• pp.1797-1800
• /
• 1996

In this study, the insulation selected in degra-dated-power cable has been observed and aging process about the insulation has been investigated. Most Insulation aging process initiates in the interface of semiconducting layer and the type of the process is the fractal form that was observed between the the semiconducting layer and insulation layer. It is possible to estimate degree of the degration of cable with breakdown test and obtained data have been used to get parameters in order to use Weibull distribution. With this method it is considered to be possible to estimate situation of degration and life prediction.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권8호
• /
• pp.907-918
• /
• 2006

In this study capacitance and dielectric loss factor were measured with low-voltage signal and the simulation of equivalent circuits for the data was conducted. As the result it was shown that the equivalent circuit model considered the grain-boundary structure with semiconducting layer, dielectric layer and depletion layer was well approximated with the observed data. Various parameters were determined by a optimum curve-fitting method and could be used to analyze the characteristics of varistor. It also seems that the proposed equivalent circuit model will be adopted for other BL type varistors.