Preparation and Thermoelectric Property of Highly Oriented Al-Doped ZnO Ceramics by a High Magnetic Field

Kaga, Harumi; Kinemuchi, Yoshiaki; Tanaka, Satoshi; Makiya, Atsushi; Kato, Zenji; Uematsu, Keizo

doi:10.1143/jjap.45.l1212

Cited by 32 publications

(27 citation statements)

References 22 publications

(24 reference statements)

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“…The thermal conductivity of ZnO is basically high due to its light constituent elements and bonding nature, and it exceeds 100 W/m K for a single crystal 9 and 30 W/m K to 40 W/m K for polycrystalline bulk prepared by conventional sintering. 10,11 Hot-pressing of nanoparticles synthesized by coprecipitation results in a reduction in thermal conductivity to 20 W/m K, 12 because grain growth during hot-pressing results in a grain size of 1 lm, although the starting material was in the nanometer range. Grain sizes down to 100 nm result in thermal conductivity comparable to that of SiGe alloys.…”

Section: Resultsmentioning

confidence: 99%

Thermoelectric Properties of Nanograined ZnO

Kinemuchi

Mikami

Kobayashi

et al. 2009

Journal of Elec Materi

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Bulk ZnO with a grain size of 20 nm was successfully obtained by pulsed electric current sintering. The crystalline size was almost identical to that of the raw particles, because the sintering temperature was as low as 200°C. A pressure of 500 MPa effectively enhanced densification, leading to a relative density of >90% at 200°C. The small grain size led to a low thermal conductivity of 3 W/m K at room temperature, due to enhanced boundary scattering. The Seebeck coefficient was higher than that of micrograined ZnO with similar Ga doping (0.3 at.% Ga). However, the resistivity was increased by more than 1000 times. The temperature dependence of conductivity showed thermally activated conduction behavior, while that of micrograined ZnO exhibited metallic-like behavior. The thermoelectric properties suggest that a carrier trap in the nanograined ZnO hinders carrier transport. Surface modification of the ZnO nanoparticles by heat treatment in H 2 resulted in observable photoluminescence which was quenched in the starting nanoparticles, and led to a decrease in the resistivity of the sintered bulk, which indicates that control of surface defects on the nanoparticles is crucial for enhancement of the thermoelectric properties of nanograined ZnO.

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Section: Resultsmentioning

confidence: 99%

Thermoelectric Properties of Nanograined ZnO

Kinemuchi

Mikami

Kobayashi

et al. 2009

Journal of Elec Materi

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“…After annealing at 400 • C, the intensified (0 0 2) peak implies that the crystallinity of the c-axis oriented grains has been improved and the grain size has been enlarged. As (0 0 2) textured AZO films have been proved to be superior in terms of electrical conductivity [26][27][28], the enlarged (0 0 2) oriented grains along with the release of residual stress which are labeled as positive factors here can account for the early decrease of R s in Fig. 2.…”

Section: Microstructure and Surface Morphologymentioning

confidence: 95%

Thermal stability of electrical properties of ZnO:Al films deposited by room temperature magnetron sputtering

Wang

Diao

Ding

2011

Journal of Alloys and Compounds

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“…Among the doped ZnO samples reported thus far, Al-doped ZnO exhibited the highest ZT value. [9][10][11][12][13][14][15][16][17] A relatively high thermal conductivity within the range of 20-40 WÁm À1 ÁK À1 at room temperature, generally observed in doped ZnO samples, prevents us from obtaining a considerably large ZT value. Therefore, it is very important to decrease the lattice thermal conductivity of ZnO-based materials for thermoelectric applications.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Properties of Solution Combustion Synthesized Al-Doped ZnO

et al. 2008

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Thermoelectric properties of Al-doped ZnO prepared by solution combustion synthesis using urea as fuel and sintered by spark plasma sintering were investigated for developing an energy-and time-saving synthesis method to decrease its thermal conductivity without a significant deterioration in other thermoelectric properties. The desired materials were successfully synthesized and sintered. The thermoelectric properties of the synthesized products subjected to planetary ball milling (PBM) treatment before sintering were compared with those of synthesized products not subjected to PBM treatment; the results showed that the former products had a larger power factor and higher thermal conductivity than the latter products. The thermal conductivity of all as-synthesized products was in the range of 8.3-19.7 WÁm À1 ÁK À1 at room temperature, which was significantly lower than that of the products synthesized by a conventional solid-state reaction method. (Zn 0:99 Al 0:01 )O obtained by PBM had the highest dimensionless figure of merit ZT of 0.050 at 863 K. From these results, it is inferred that solution combustion synthesis is an effective method for synthesizing Al-doped ZnO with relatively low thermal conductivity for high-temperature thermoelectric applications.

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Preparation and Thermoelectric Property of Highly Oriented Al-Doped ZnO Ceramics by a High Magnetic Field

Cited by 32 publications

References 22 publications

Thermoelectric Properties of Nanograined ZnO

Thermoelectric Properties of Nanograined ZnO

Thermal stability of electrical properties of ZnO:Al films deposited by room temperature magnetron sputtering

Thermoelectric Properties of Solution Combustion Synthesized Al-Doped ZnO

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