• Journal of Powder Materials
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• v.8 no.2
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• pp.110-116
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• 2001

Abstract To investigate the effect of mechanical alloying process to thermoelectric properties of PbTe sintered body, Pb-Te mixed powder with Pb : Te : 1 : 1 composition was mechanically alloyed using tumbler-ball mill. Thermoelectric properties of the sintered body were evaluated by measuring of the Seebeck coefficient and specific electric resistivity from the room temperature to 50$0^{\circ}C$. Sintered body of only mechanically alloyed PbTe powder showed p-type behavior at the room temperature, and occurred type transition from p-type to n-type at about 30$0^{\circ}C$. PbTe sintered body which was fabricated using heat treated powder in $H_2$ atmosphere after mechanical alloying showed stable n-type behavior under 50$0^{\circ}C$. N-type PbTe sintered body fabricated by mechanical alloying process had 4 times higher power factor than that fabricated by the melt-crushing process. Application of a mechanical alloying process to fabricate of n-type PbTe thermoelectric material seemed to be useful to increase the power factor of PbTe sintered body.

• Korean Journal of Materials Research
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• v.5 no.2
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• pp.223-231
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• 1995

Mechanical alloying behavior of the PbTe intermetallic compound, which is used for thermoelectric generation, has been investigated with milling time and ball-to-powder weight ratio. Formation of PbTe alloy was completed by mechanical alloying of the as-mixed Pb and Te powders for 2 minutes at ball-to-powder weight ratio of 2 : 1. In situ measurement of the abrupt temperature rise during the ball milling process indicated that the PbTe intermetallic compound was formed by a self-sustained reaction rather than diffusional reactions. Lattice constant of PbTe alloy fabricated by mechanical alloying, 0. 6462nm, was not varied with milling time and ball-to-powder weight ratio. This value of the lattice parameter is in excellent agreement with 0.6459nm, which was reported for PbTe powders processed by melting and grinding.

• Journal of Sensor Science and Technology
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• v.7 no.1
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• pp.67-72
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• 1998

The crystallized CuPc and PbTe films are formed by thermal evaporation and pulsed ArF excimer laser ablation. Structural and electrical properties of thin film is observed by XRD and current-voltage(I-V) curves. From XRD analysis, both PbTe and CuPc thin films show a-axis oriented structure. For the measurement of photovoltaic effect, the transverse current-voltage curve of CuPc/Si, PbTe/Si and PbTe/CuPc/Si junctions have been analyzed in the dark and under illumination. The PbTe/CuPc/Si junction exthibits a strong photovoltaic characteristics with short circuit current($J_{sc}$) of $25.46\;mA/cm^{2}$ and open-circuit voltage($V_{oc}$) of 170 mV. Quantum efficiency and power conversion efficiency are calculated to be 15.4% and $3.46{\times}10^{-2}$, respectively. Based on the results of QE and ${\eta}$, the photocurrent process of PbTe/CuPc/Si junction can be explained as following three effective steps; photocarrier generation in the CuPc layer, carrier separation at PbTe/CuPc interface, and finally a transportation of electrons through the PbTe layer.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1223-1224
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• 2006

The p-type $(Bi_{0.2}Sb_{0.8})_2Te_3/(Pb_{0.7}Sn_{0.3})$Te functional gradient material (FGM) was fabricated by hot-pressing the mechanically alloyed $(Bi_{0.2}Sb_{0.8})_2Te_3$ and the 0.5 at% $Na_2Te-doped$ $(Pb_{0.7}Sn_{0.3})Te$ powders. Also, the n-type $Bi_2(Te_{0.9}Se_{0.1})_3/PbTe$ FGM was processed by hot-pressing the mechanically alloyed $Bi_2(Te_{0.9}Se_{0.1})_3$ and the 0.3 wt% Bi-doped PbTe powders. With ${\Delta}T$ larger than $300^{\circ}C$, the p-type $(Bi_{0.2}Sb_{0.8})_2Te_3/(Pb_{0.7}Sn_{0.3})Te$ FGM exhibited larger thermoelectric output power than those of the $(Bi_{0.2}Sb_{0.8})_2Te_3$ and the 0.5 at% $Na_2Te-doped$ $(Pb_{0.7}Sn_{0.3})Te$ alloys. For the n-type $Bi_2(Te_{0.9}Se_{0.1})_3/PbTe$ FGM, the thermoelectric output power superior to those of the $Bi_2(Te_{0.9}Se_{0.1})_3$ and the 0.3 wt% Bi-doped PbTe was predicted at ${\Delta}T$ larger than $300^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.599-604
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• 2011

A highly strained nanostructure comprising crystallographically aligned HgTe nanoinclusions and a surrounding PbTe matrix has been synthesized using a precipitation process of supersaturated HgTe-PbTe alloys. From the early precipitation stage, HgTe nanoinclusions take disk shape, which is transformed from initial HgTe nuclei, although there is no lattice constant difference of the two end components at standard state. As a primary reason for the morphological transformation of the initial spherical HgTe nuclei to HgTe nanodisks, the induced lattice mismatch is suggested. On the condition that the HgTe nanodisks maintain perfect coherent nature with PbTe matrix, the stress-free lattice constant of constrained HgTe nanodisks has been calculated based on the defined concept of the strain-induced tetragonality, the linear elasticity and the actual measurement in HRTEM images.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1055-1060
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• 1998

Thermoelectric properties of ($Pb_{1-x}Sn_x$)Te ($0\leq{x}\leq{0.4}$) alloys, fabricated by mechanical alloying and hot pressing, were investigated with variation of the SnTe content. For the hot-pressed PbTe and ($Pb_{0.9}Sn_{0.1}$)Te. transition from p-type to n-type occurred at $200^{\circ}C$ and $300^{\circ}C$, respectively. However, the specimens containing SnTe more than 0.2mole exhibited p-type conduction up to 450'C. In extrinsic conduction region, the Seebeck coefficient and electrical resistivity of the hot-pressed ($Pb_{1-x}Sn_x$)Te decreased with increasing the SnTe content. The temperature at which the hot-pressed (Pbl-,Sn,)Te exhibited a maximum figure-of-merit was shifted to higher temperature with increasing the SnTe content The hot-pressed (Pbo ,Sno dTe exhibited a maximum figure-of-merit of $0.68\times10_{-3}/K$ at $200^{\circ}C$.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.911-917
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• 2002

0.5 at% $Na_2$Te-doped ($Pb_{0.7}Sn_{0.3}$)Te and ($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ powders were fabricated by mechanical alloying process. 0.5 at% Na$_2$Te-doped ($Pb_{0.7}Sn_{0.3}$)Te powders were charged at one end of mold and ($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ powders were charged at the other end of a mold. Then these powders were hot-pressed to form p-type ($Pb_{0.7}Sn_{0.3}$)Te/($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ functional gradient materials with the segment ratios (the ratio of ($Pb_{0.7}Sn_{0.3}$)Te to ($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ ) of 1:2, 1:1, and 2:1. Power generation characteristics of the ($Pb_{0.7}Sn_{0.3}$)Te/($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ were measured. When the temperature difference ΔT at both ends of the specimen was larger than $300^{\circ}C$, the ($Pb_{0.7}Sn_{0.3}$)Te/($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ with the segment ratios of 1:2 and 1:1 exhibited larger output power than those of the ($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ and 0.5 at% $Na_2$ Te-doped ($Pb_{0.7}Sn_{0.3}$)Te alloys. The maximum output power of the ($Pb_{0.7}Sn_{0.3}$)Te/($Bi_{0.2}Sb_{0.8}$)$_2$$Te_3$ predicted with the measured Seebeck coefficient and the estimated electrical resistivity was in good agreement with the measured maximum output power.

• Journal of Sensor Science and Technology
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• v.8 no.2
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• pp.184-188
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• 1999

PbTe thin films of high quality were deposited on HF-treated Si(100) substrates at various substrate temperature by pulsed laser deposition technique. XRD patterns showed that PbTe layers were well-crystallized to a cubic phase with (h00) preferred orientation with the substrate temperature up to $300^{\circ}C$. PbTe films could not form at substrate temperature above $400^{\circ}C$ because of reevaporation of the Pb. According to AFM image, the surface of films was composed of small granular crystals and flat matrix. According to the increase of substrate temperature, the grain size at film surface becomes larger. By Hall-effect measurement, the carrier concentration and Hall mobility of n-type PbTe films grown by $T_{sub}=300^{\circ}C$ were $3.68{\times}10^{18}cm^{-3}$ and $148\;cm^2/Vs$, respectively.

• Korean Journal of Materials Research
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• v.8 no.3
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• pp.245-251
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• 1998

Bi-doped n-type PbTe thermoeletric materials were fabricated by mechanical alloying and hot pressing. The intering characteristics and thermoelectric properties of the hot- pressed PbTe were characterized and compared with the properties of the specimens prepared by meltingigrinding method. The hot-pressed PbTe specimens fabricated by mechanical alloying exhibited more negative Seebeck coefficient, higher electrical resistivity and lower thermal conductivity. compared to ones prepared by meltingigrinding. The maximum figure-of-merit increased and the temperature for the maximum figure-of-merit shifted to lower temperature for the specimens fabricated by mechanical alloying. When hot pressed at $650^{\circ}C$, 0.3 wt% Bi-doped PbTe fabricated by mechanical alloying and meltingjgrinding exhibited maximum figure-of-merits of $1.33\times10^{-3}/K$ at $200^{\circ}C$ and $1.07\times10^{-3}/K$ at $400^{\circ}C$ respectively.

• Korean Journal of Metals and Materials
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• v.48 no.2
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• pp.175-179
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• 2010

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 $1.8W/m{\cdot}K$ 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.