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Thermal Conductivity in Individual Single-Crystalline PbTe Nanowires
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노종욱 Jong Wook Roh , 장소영 So Young Jang , 강주훈 Joo Hoon Kang , 이승현 Seung Hyun Lee , 노진서 Jin Seo Noh , 박정희 Jeung Hee Park , 이우영 Woo Young Lee |
KJMM 48(2) 175-179, 2010 |
ABSTRACT
We investigated the thermal conductivity of individual single-crystalline PbTe nanowires grown by chemical vapor transport method. Suspended MEMS was utilized to precisely measure the thermal conductivity of an individual nanowire. The thermal conductivity of a PbTe nanowire with diameter of 292 nm was measured to be 1.8 W/m·K at 300 K, which is about two thirds of that of bulk PbTe. This result indicates that the thermal conduction through a PbTe nanowire is effectively suppressed by the enhanced phonon boundary scattering. As the diameter of a PbTe nanowire decreases, the corresponding thermal conductivity linearly decreases.
keyword : PbTe, thermoelectric materials, thermal conductivity, crystal growth, focused ion beam
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Effect of Post Heat Treatment on Field Emission Properties for Carbon Nanotube Cathodes
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하상훈 Sang Hoon Ha , 권나현 Na Hyun Kwon , 송풍근 Pung Keun Song , 장지호 Ji Ho Chang , 조영래 Young Rae Cho |
KJMM 48(2) 180-186, 2010 |
ABSTRACT
For the application of field emission display (FED), it is essential to develop a carbon nanotube (CNT) cathode with high emission current density. In this study, we developed and demonstrated a post-heat treatment (PHT) process to improve field emission properties of CNT cathodes. Since the PHT is intended to burn out organic materials covering the CNTs, the PHT was carried out by heating samples at a high temperature in an atmosphere. The PHT process is applied for samples processed by surface treatment with an adhesive tape. Compared to samples prior to the PHT, samples after the PHT at 360℃ showed about 17% improvement in emission current density. The major reason for the increased current density is mainly the increased aspect ratio of the CNTs because of the removal of the adhesive organic residues covering the CNTs, which were attached on the CNT surfaces during the surface treatment using the adhesive taping method.
keyword : field emission, carbon and graphite, surface modification, electrical properties, scanning electron microscopy, SEM
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