Effect of Vacancy Distribution on the Thermal Conductivity of Ga2Te3 and Ga2Se3

Kim, Chang-Eun; Kurosaki, Ken; Ishimaru, Manabu; Muta, Hiroaki; Yamanaka, Shinşuke

doi:10.1007/s11664-010-1479-7

Cited by 39 publications

(32 citation statements)

References 14 publications

(14 reference statements)

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“…Such an occurrence has been previously observed for annealed specimens of the binary compound Ga 2 Te 3 [14,15]. High resolution electron microscopy images of Ga 2 Te 3 have shown the presence of vacancy planes along the [111] direction occurring periodically at 3.5 nm intervals [14,15]. Examining the two pairs of satellite peaks in the Ga 2 ðSe 0:3 Te 0:7 Þ 3 diffraction pattern, the intensities of the peaks on opposites sides of the (111) Bragg line are not commensurate with each other, indicative of short range vacancy ordering in as-grown specimens.…”

Section: Structure Characterizationsupporting

confidence: 73%

“…3 highlights the presence of satellite peaks around the (111) Bragg line not associated with crystal lattice reflections. Such an occurrence has been previously observed for annealed specimens of the binary compound Ga 2 Te 3 [14,15]. High resolution electron microscopy images of Ga 2 Te 3 have shown the presence of vacancy planes along the [111] direction occurring periodically at 3.5 nm intervals [14,15].…”

Section: Structure Characterizationsupporting

confidence: 69%

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Single crystal growth of Ga2(SexTe1−x

Abdul-Jabbar

Bourret-Courchesne

Wirth

2012

Journal of Crystal Growth

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a b s t r a c tSmall single crystals of Ga 2 ðSe x Te 1Àx Þ 3 semiconductors, for x ¼0.1, 0.2, 0.3, were obtained via modified Bridgman growth techniques. High resolution powder x-ray diffractometry confirms a zincblende cubic structure, with additional satellite peaks observed near the (111) Bragg line. This suggests the presence of ordered vacancy planes along the [111] direction that have been previously observed in Ga 2 Te 3 . Defect studies via positron annihilation spectroscopy show an average positron lifetime of % 400 ps in bulk as-grown specimens. Such a large lifetime suggests that the positron annihilation sites in these materials are dominated by defects. Moreover, analyzing the electron momenta via coincidence Doppler broadening measurements suggests a strong presence of large open-volume defects, likely to be vacancy clusters or voids.

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Section: Structure Characterizationsupporting

confidence: 73%

Section: Structure Characterizationsupporting

confidence: 69%

Single crystal growth of Ga2(SexTe1−x

Abdul-Jabbar

Bourret-Courchesne

Wirth

2012

Journal of Crystal Growth

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“…In addition, the thermal conductivity of Y 2 O 3 –ZrO 2 –HfO 2 solid solution, which is considered a strong candidate for TBCs, is much lower than that of either Y 2 O 3 –ZrO 2 or Y 2 O 3 –HfO 2 at the same Y 2 O 3 concentration because of the substitution of Zr 4+ and Hf 4+ ions (here the dopant atoms occupying various lattice sites represent point defects). Recently, it has been reported that phonons are more effectively scattered by planar defects than by point defects, which is the main reason for a relatively low thermal conductivity of Ga 2 Se 3 containing planar defects . Lattice defects usually scatter both phonons and electrons.…”

Section: Introductionmentioning

confidence: 99%

Effect of point and planar defects on thermal conductivity of TiO_2−x

Ohishi

Muta

et al. 2017

J Am Ceram Soc

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In this study, we have investigated the effect of planar defect on thermal and electron transport as compared to point defect in the rutile TiO 2Àx . Two series of bulk TiO 2Àx (2Àx = 2.000, 1.992, 1.985, 1.972, and 1.934) samples were prepared using different heat-treatment procedures to clearly identify the presence of point and planar defects via powder X-ray diffraction. The charge carrier density and mobility were determined from the Hall effect measurements using the van der Pauw method. The elastic properties of the studied materials such as bulk modulus, shear modulus, Young's modulus, compressibility, and Debye temperature were evaluated from the measured sound velocities, while their thermal conductivities were determined from the thermal diffusivities, heat capacities, and densities measured in the temperature range between 300 and 1073 K. The theoretical calculation based on Klemens-Callaway model has been performed to analyze the thermal conductivity. As a result, the effect of planar defects on the carrier mobility was almost equivalent to the effect produced by point defects. On the other hand, the presence of planar defects significantly reduced the thermal conductivity of TiO 2Àx as compared to point defect due to strong phonon scattering induced by planar defects.

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“…The sample with the point type vacancies exhibited relatively high ¬ lat (= 1.3 W m ¹1 K ¹1 at 300 K) with a T ¹1 temperature dependence, while the sample with the in-plane type vacancies exhibited quite low ¬ lat (= 0.6 W m ¹1 K ¹1 at 300 K) with rather flat temperature dependence. 6) In addition to the vacancy distribution described above, the amount of vacancies would also influence the TE properties. However, the effect of the amount of vacancies on the TE properties has not been investigated.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Amount of Vacancies on the Thermoelectric Properties of Cu–Ga–Te Ternary Compounds

et al. 2012

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The CuGaTe ternary compounds: Cu 3 Ga 5 Te 9 , Cu 2 Ga 4 Te 7 , CuGa 3 Te 5 , CuGa 5 Te 8 , and CuGaTe 2 have zinc-blende or chalcopyrite structure. The compounds except for CuGaTe 2 contain vacancies in the cation site due to the valence mismatch between cation and anion, and the vacancy concentration is different between these compounds. Here we investigated the effect of the amount of vacancies on the thermoelectric (TE) properties of the CuGaTe ternary compounds. At room temperature, the presence of vacancies reduced the Hall mobility (® H ) and the lattice thermal conductivity (¬ lat ), showing that the vacancies scattered both carriers and phonons. It was found that the decreasing rate of the ® H was larger than that of the ¬ lat . Therefore, the presence of vacancies degraded the TE performance of the CuGaTe ternary compounds. In other words, CuGaTe 2 without vacancies would show the best TE figure of merit. The room temperature ZT values for Cu 3 Ga 5 Te 9 , Cu 2 Ga 4 Te 7 , CuGa 3 Te 5 , CuGa 5 Te 8 , and CuGaTe 2 were 2.0 © 10 ¹2

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Effect of Vacancy Distribution on the Thermal Conductivity of Ga2Te3 and Ga2Se3

Cited by 39 publications

References 14 publications

Single crystal growth of Ga2(SexTe1−x

Single crystal growth of Ga2(SexTe1−x

Effect of point and planar defects on thermal conductivity of TiO_2−x

Effect of the Amount of Vacancies on the Thermoelectric Properties of Cu–Ga–Te Ternary Compounds

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Effect of Vacancy Distribution on the Thermal Conductivity of Ga2Te3 and Ga2Se3

Cited by 39 publications

References 14 publications

Single crystal growth of Ga2(SexTe1−x

Single crystal growth of Ga2(SexTe1−x

Effect of point and planar defects on thermal conductivity of TiO2−x

Effect of the Amount of Vacancies on the Thermoelectric Properties of Cu&ndash;Ga&ndash;Te Ternary Compounds

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Product

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Effect of point and planar defects on thermal conductivity of TiO_2−x

Effect of the Amount of Vacancies on the Thermoelectric Properties of Cu–Ga–Te Ternary Compounds