• Korean Journal of Materials Research
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• v.16 no.6
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• pp.377-381
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• 2006

Skutterudite $CoSb_3$ doped with nickel was prepared by encapsulated induction melting, and its doping effects on thermoelectric properties were investigated. Single phase ${\delta}-CoSb_3$ was successfully obtained by encapsulated induction melting and subsequent heat treatment at 773 K for 24 h. Nickel atoms acted as electron donors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by appropriate heat treatment and doping, and they were closely related to phase transitions and dopant activation. The maximum ZT(dimensionless figure of merit) was achieved as 0.2 at 600 K for the $Co_{0.93}Ni_{0.07}Sb_3$ specimen.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.66-66
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• 1997

• Tribology and Lubricants
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• v.13 no.1
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• pp.34-41
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• 1997

Frictional behavior of three automotive friction materials (brake pads) containing different amounts of antimony trisulfide ($Sb_2S_3$) and zirconium silicate ($ZRSiO_4$) were investigated using a front brake system. The friction materials were tested on a brake dynamometer (dyno) with gray cast iron rotors. The dynamometer(dyno) test simulated the dragging of a ehicle maintaining 70 km/h and vehicle stops from 100 km/h using 20 different combinations of initial brake temperature (IBT) and input pressure (IP). The results showed a strong influence of the relative amount of $Sb_2S_3$ and $ZrSiO_4$ in friction materials on friction characteristics. Friction stability was improved with the higher concentration of $Sb_2S_3$ in the friction material. Torque variation during drag cycle was increased with an increase of the $ZrSiO_4$ concentration in the friction material. Average friction coefficient and the wear rate of the friction material increased by using more aggressive friction materials containing more $ZrSiO_4$ and less $Sb_2S_3$. Generation of the disk thickness variation (DTV) increased when friction materials with higher concentration of $ZrSiO_4$ were used Careful examination of DTV change showed that aggressiveness of the friction material played an important role in determining torque variation.

• Korean Journal of Materials Research
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• v.12 no.3
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• pp.169-175
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• 2002

Semiconductive nano $(Ba_{1-x}Sb_x)TiO_3$ powders were synthesized by the hydrothermal process and Sb was simultaneously doped in the hydrothermal condition. $(Ba_{1-x}Sb_x)TiO_3$ powders obtained from optimum condition(at 20$0^{\circ}C$ for 3hr) exhibited spherical shape, high purity and nano size. The PTCR characteristics was observed when 0.1 and 0.2 mole% Sb were added and sintered at over 130$0^{\circ}C$ for 1 hour, respectively. And The ceramics exhibit the PTCR characteristics with a resistively jump $ratio($\rho$_{max}/$\rho$_{min})$ of about $10^4$. Also we found that PTCR characteristics were dependent on the microstructure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.268-271
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• 2004

The phase transition from amorphous to crystalline states, and vice versa, of $Ge_2Sb_2Te_5$ films by applying electrical pulses have been studied. This material can be used as nonvolatile memory. The reversible phase transition between the amorphous and crystalline states, which is accompanied by a considerable change in electrical resistivity, is exploited as means to store bits of information. The nonvolatile memory cells are composed of a simple sandwich (metal/chalcogenide/metal). It was formed that the threshold voltage depends on thickness, electrode distance, annealing time and temperature, respectively.

• Journal of the Korean Ceramic Society
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• v.49 no.1
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• pp.43-47
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• 2012

Electromigration in molten $Ge_2Sb_2Te_5$ (GST) was characterized using pulsed DC stress to an isolated line structure. When an electrical pulse was applied to the GST, GST lines were melted by Joule heating, and Ge and Sb atoms migrate to the cathode, whereas Te atoms migrate to the anode. This elemental separation in the molten GST was caused by an electrostatic force-induced electromigration. The effects of O-, N-, and Bi-doping on the electromigration were also investigated, and atomic mobility changes by the doping were investigated by quantifying $DZ^*$ values. The Bi -doping did not affect the $DZ^*$ values of the constituent atoms in the molten GST, but the D$DZ^*$ values decreased by O-doping and N-doping.

• Journal of Powder Materials
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• v.15 no.5
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• pp.352-358
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• 2008

The present study focused on the synthesis of a bismuth-antimony-tellurium-based thermoelectric nanopowders using plasma arc discharge process. The chemical composition, phase structure, particle size of the synthesized powders under various synthesis conditions were analyzed using XRF, XRD and SEM. The powders as synthesized were sintered by the plasma activated sintering. The thermoelectric properties of sintered body were analyzed by measuring Seebeck coefficient, specific electric resistivity and thermal conductivity. The chemical composition of the synthesized Bi-Sb-Te-based powders approached that of the raw material with an increasing DC current of the are plasma. The synthesized Bi-Sb-Te-based powder consist of a mixed phase structure of the $Bi_{0.5}Sb_{1.5}Te_{3}$, $Bi_{2}Te_{3}$ and $Sb_{2}Te_{3}$ phases. This powder has homogeneous mixing state of two different particles in an average particle size; about 100nm and about 500nm. The figure of merit of the sintered body of the synthesized 18.75 wt.%Bi-24.68 wt.%Sb-56.57 wt.%Te nanopowder showed higher value than one of the sintered body of the mechanically milled 12.64 wt.%Bi-29.47 wt.%Sb-57.89 wt.%Te powder.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.94-98
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• 1996

The x-ray diffraction experiments were carried out to investigate the phase transformation of the sputter-deposited Ag-In-Sb-Te optical thin films after rapid thermal annealing and while being annealed with high-temperature x-ray attachment. The formation mechanism of the reported mixed phase, with both amorphous phase and fine crystalline AgSbTe2 phase, of Ag-In-Sb-Te system in its ordered state was explained. Moreover the characteristics of the other phases which appear during the annealing processes were also discussed in the present article.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.100-100
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• 2003

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.35-35
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• 2005