Lattice Thermal Conductivity of Deformed Lithium Fluoride Crystals at Low Temperatures

Kumar, Anil; Srivastava, Bipin K.; Ansari, M. Afzal

doi:10.1002/pssb.2221380206

Cited by 8 publications

(2 citation statements)

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“…The phonon scattering by SFs is previously ignored by most researchers probably because the appearance of SFs is also accompanied with the linear defects of dislocations at the end of this planar defect, 50 which have different frequency-dependent relaxation rates (ω 3 dependence for dislocation cores and ω dependence for dislocation strain). 48 However, as introduced by Kumar et al, 52 the phonon scattering by dislocations can also be represented by a term of ω 2 dependence relaxation rate when considering the overlapping of phonon scattering between point defects (PDs) and dislocations. Thus, to simplify the theoretical modeling process, we use ω 2 dependence relaxation rate in eq 3 to also include the phonon scattering contribution from those additional dislocations derived from the SFs.…”

Section: Resultsmentioning

confidence: 99%

Stacking Fault-Induced Minimized Lattice Thermal Conductivity in the High-Performance GeTe-Based Thermoelectric Materials upon Bi₂Te₃ Alloying

Xie

Zhang

et al. 2019

ACS Appl. Mater. Interfaces

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Materials with low lattice thermal conductivity (κlat) are crucial for the applications of thermal insulation and thermoelectric (TE) energy conversion. Stacking fault (SF)-induced phonon scattering within interfaces has been put forward theoretically by Klemens in 1950s. However, unlike other traditional defects such as point defects, grain boundaries, and dislocations, the role of SF for reducing κlat remains poorly understood and is yet to be revealed experimentally. The layered Bi2Te3 with a van der Waals gap shows different stacking structures than the nonlayered GeTe, which is used to introduce SFs into the GeTe-based alloys in this work. On the basis of the experimental and theoretical modeling results, this paper reveals the significant contribution of SF phonon scattering for minimizing the κlat. Besides the achieved extremely low κlat (∼0.39 W m–1 K–1 at 573 K), optimized carrier density and band convergence are also realized in the GeTe-based alloys upon Bi2Te3 alloying, leading to a significant high TE figure of merit ZT > 2 at 773 K and an averaged ZT > 1.4 within 300–773 K. This SF engineering strategy provides a different avenue to reduce the κlat for enhancing the performance of thermal insulation and TE materials.

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Section: Resultsmentioning

confidence: 99%

Stacking Fault-Induced Minimized Lattice Thermal Conductivity in the High-Performance GeTe-Based Thermoelectric Materials upon Bi₂Te₃ Alloying

Xie

Zhang

et al. 2019

ACS Appl. Mater. Interfaces

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“…In fact, it is described as the static dislocation-phonon scattering processes due to elastic strain fields produced around the dislocation. The magnitude of K,,(T) may be obtained by including an additional phonon scattering due to the simultaneous presence of static dislocation scattering and massdifference scattering processes, as calculated by Kumar et al [5]. The relaxation time for the additional scattering is given by the following relation:…”

Section: Effect Of Mass-difference Scattering On Static Dislocation Smentioning

confidence: 99%

Effect of mass‐difference scattering on static dislocation scattering in neutron‐irradiated silicon

Biswas¹,

Kumar

1992

Physica Status Solidi (b)

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The simultaneous presence of the various phonon scattering processes can produce interference terms which may be significant to analyse the entire temperature dependence of the lattice thermal conductivity. Carruthers 111 suggested that the interference between elastic scattering can be separately recognized as the interference between 1. the same kind of scatterers (e.g. an array of dislocations) and 2. scatterers of different kinds. Klemens [2] has previously calculated the interference between different kinds of scatterers and found that the effective scattering is enhanced.Recently Pompe et al. [3] have analysed the lattice thermal conductivity of neutronirradiated silicon crystals with different fast neutron doses on the basis of the Callaway model [4] and have also observed their changes by annealing. At relatively high neutron doses the effects can be described by point defects [2] and by extended defects of the kind of dislocations or dislocation loops, respectively. In the present note, an analysis has been done to study quantitatively the nature of the scattering of phonons by these structure defects produced in the silicon crystal due to the neutron irradiation.Pompe et al. [3] have found that the temperature dependence of Kph(T) can be analysed by introducing a scattering process of the kind of phonon-dislocation interaction. The relaxation time for phonon-dislocation interaction is expressed as 2 -l = DO&, (1) where D measures the strength of the phonon-dislocation interaction in terms of dislocation density, Gruneisen constant, and Burgers vector. In fact, it is described as the static dislocation-phonon scattering processes due to elastic strain fields produced around the dislocation. The magnitude of K,,(T) may be obtained by including an additional phonon scattering due to the simultaneous presence of static dislocation scattering and massdifference scattering processes, as calculated by Kumar et al. 2;l = Aw;A.Klemens has studied the impuricity-phonon scattering and expressed the results as I) Kharagpur 721 302, India.

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Effect of Dislocations on the Thermal Conductivity of Ice and Ice Clathrate

Biswas¹,

Kumar

1991

Physica Status Solidi (b)

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Recently Ahmad and Phillips /I/ observed that the T2 dependence of the thermal conductivity of ice clathrates is due to the tunneling states arising from proton disorder 121. The thermal conductivity of ice clathrat'e was otherwise assumed to resemble the thermal conductivity of amorphous materials 131. The other important parameter to analyse their thermal conductivity is found to be the dislocation density of the order of 1014 rn-' in such materials which is quite higher than that normally found in non-metals in earlier calculations 141. In the present note we study the effect of dislocations on the thermal conductivity of ice clathrates at low temperatures when the dislocation density is large.The thermal conductivity of ice clathrate hydrates is found to be markedly different from that of ice between 40 K and room temperature unlike the properties such as sound velocity and electrical resistivity which are almost the same due to the similarities in their lattice structures. The clathrate hydrates are crystalline in 2 nature though the temperature dependence of the thermal conductivity curve is T dependent. It is therefore interesting to compare the results of the thermal conductivity of clathrates with that of ice as shown in Fig. 1. The thermal conductivity of ice and its clathrates is calculated by using the Callaway relation which can be summarized aswhere C(w,T) is the specific heat at temperature T, l(w,T) is the mean free path, and v(w,T) is the phonon velocity. Ahmad and Phillips /I/ have suggested that due to the typical characteristics of the density of phonons states, a constant v with Debye-like density of vibrational states is a good approximation to study the presence of dislocations and proton disorder in clathrates .Klinger and Rochas /5/ have analysed the thermal conductivity data of ice of linear dimensions by considering l ) Purulia, West Bengal, India. where the first term is the boundary scattering, the second is due to dislocation scattering, and the last *term represents the umklapp scattering processes. From the temperature dependence of the relaxation time for phonon-phonon scattering processes the value of s can vary from 1 to 4 . A best fit /6/ between theory and experiment can be obtained by including the normal phonon-phonon and isotopic scattering processes, the effective relaxation may then be expressed as T -l ( w ,~) = 1 + + DU 3 + B~U 2 3

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Lattice Thermal Conductivity of Deformed Lithium Fluoride Crystals at Low Temperatures

Cited by 8 publications

References 21 publications

Stacking Fault-Induced Minimized Lattice Thermal Conductivity in the High-Performance GeTe-Based Thermoelectric Materials upon Bi₂Te₃ Alloying

Stacking Fault-Induced Minimized Lattice Thermal Conductivity in the High-Performance GeTe-Based Thermoelectric Materials upon Bi₂Te₃ Alloying

Effect of mass‐difference scattering on static dislocation scattering in neutron‐irradiated silicon

Effect of Dislocations on the Thermal Conductivity of Ice and Ice Clathrate

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Lattice Thermal Conductivity of Deformed Lithium Fluoride Crystals at Low Temperatures

Cited by 8 publications

References 21 publications

Stacking Fault-Induced Minimized Lattice Thermal Conductivity in the High-Performance GeTe-Based Thermoelectric Materials upon Bi2Te3 Alloying

Stacking Fault-Induced Minimized Lattice Thermal Conductivity in the High-Performance GeTe-Based Thermoelectric Materials upon Bi2Te3 Alloying

Effect of mass‐difference scattering on static dislocation scattering in neutron‐irradiated silicon

Effect of Dislocations on the Thermal Conductivity of Ice and Ice Clathrate

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Stacking Fault-Induced Minimized Lattice Thermal Conductivity in the High-Performance GeTe-Based Thermoelectric Materials upon Bi₂Te₃ Alloying

Stacking Fault-Induced Minimized Lattice Thermal Conductivity in the High-Performance GeTe-Based Thermoelectric Materials upon Bi₂Te₃ Alloying