Diffusion-Mediated Anharmonic Phonon Transport and Thermal Conductivity Reduction in Defective Hybrid Perovskites

2021 ◽  
Author(s):  
Zhuangli Cai ◽  
Zuolin Liu ◽  
Bin Yang ◽  
Min Yang ◽  
Shangchao Lin
Keyword(s):  
Thermal Conductivity ◽  
Phonon Transport ◽  
Vacancy Defect ◽  
Metal Halide ◽  
Theoretical Research ◽  
Lead Iodide ◽  
Vacancy Defects ◽  
Defect Migration ◽  
Phonon Relaxation Time ◽  
Dynamics Simulations

Abstract Hybrid metal halide perovskite is a promising material for efficient photovoltaic cells and potential thermoelectric energy conversion. This paper investigates phonon thermal transport in iodine-vacancy-defect methylammonium lead iodide (MAPbI3) perovskite using molecular dynamics simulations. The results show that the iodine vacancy defects suppress the thermal conductivity of defective MAPbI3. This effect is enhanced with increasing the defect concentration. The reduction of thermal conductivity of MAPbI3 with iodine vacancy defects compared with the pristine counterpart is mainly attributed to the enhanced phonon anharmonicity and shorter phonon relaxation time due to the phonon-defect scattering. Although iodine diffusion is observed in MAPbI3 with iodine vacancy defects, defect migration has a limited impact on mass-transfer induced convective phonon transport, while it is a source of phonon anharmonicity. This study may provide guidance for theoretical research and industrial application of as-synthesized metal halide perovskites with intrinsic defects.

Thermal conductivity of two-dimensional BC3: a comparative study with two-dimensional C3N

2019 ◽  
Vol 21 (24) ◽  
pp. 12977-12985 ◽  
Author(s):  
Jieren Song ◽  
Zhonghai Xu ◽  
Xiaodong He ◽  
Yujiao Bai ◽  
Linlin Miao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Comparative Study ◽  
Molecular Dynamics Simulations ◽  
Environmental Temperature ◽  
Single Layer ◽  
Two Dimensional ◽  
Vacancy Defects ◽  
Dynamics Simulations ◽  
External Strain

The thermal conductivities of single-layer BC3 (SLBC) sheets and their responses to environmental temperature, vacancy defects and external strain have been studied and compared with those of single-layer C3N (SLCN) sheets by molecular dynamics simulations.

MOLECULAR DYNAMICS SIMULATIONS OF CARBON NANOTUBE-BASED OSCILLATORS HAVING TOPOLOGICAL DEFECTS

2011 ◽  
Vol 10 (01n02) ◽  
pp. 355-359 ◽  
Author(s):  
MATUKUMILLI. V. D. PRASAD ◽  
BAIDURYA BHATTACHARYA
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Molecular Dynamics Simulations ◽  
Topological Defects ◽  
Oscillatory Behavior ◽  
Vacancy Defect ◽  
Single Vacancy ◽  
Vacancy Defects ◽  
The Stability ◽  
Dynamics Simulations

Effect of vacancy and Stone–Wales defects on the oscillatory behavior of (5,5)/(10,10) carbon nanotube-based oscillator are studied using NVE molecular dynamics simulations. Results show that defects reduce stability of the oscillators. Effect of single vacancy defect on stability is very small, whereas Stone–Wales defect considerably reduces the stability thereby damping the oscillations quickly. Further increase in density of vacancy defects causes a monotonic decrease of stability of oscillator. In all cases the initial temperature (1 and 300 K) had almost no effect on the oscillation stability.

Thermal Conductivity of Silicon Thin Films Predicted by Molecular Dynamics Simulations and Theoretical Calculation

2011 ◽  
Vol 55-57 ◽  
pp. 1152-1155 ◽  
Author(s):  
Xing Li Zhang ◽  
Zhao Wei Sun
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Boltzmann Transport Equation ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Boltzmann Transport ◽  
Silicon Thin Films ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Good Agreement

Molecular, dynamics simulation and the Boltzmann transport equation are used respectively to analyze the phonon transport in Si thin film. The MD result is in good agreement with the theoretical analysis values. The results show that the calculated thermal conductivity decreases almost linearly as the film thickness reduced and is almost independent of the temperature at the nanoscale. It was observed from the simulation results that there exists the obvious size effect on the thermal conductivity.

Mode-Resolved Thermal Conductivity of Freestanding and Supported Bismuth Telluride Quintuple Layer

2016 ◽  
Author(s):  
Cheng Shao ◽  
Hua Bao
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Bismuth Telluride ◽  
Normal Mode Analysis ◽  
Relaxation Times ◽  
Phonon Transport ◽  
Mode Analysis ◽  
Underlying Mechanisms ◽  
Dynamics Simulations ◽  
Phonon Properties

The successful exfoliation of atomically-thin bismuth telluride quintuple layer (QL) attracts tremendous interest in investigating the electron and phonon transport properties in this quasi-two-dimensional material. While experimental results show that thermal conductivity is significantly reduced in Bi2Te3 QL compared to the bulk phase, the underlying mechanisms for the reduction is still unclear. Also in some measurements, the Bi2Te3 QL is usually supported on the substrate and the effect of the substrate on heat transfer in Bi2Te3 QL is unknown. In this work, we have performed molecular dynamics simulations and normal mode analysis to study the mode-wise phonon properties in freestanding and supported Bi2Te3 QL. We found that the existing of substrate will decrease the phonon relaxation times in Bi2Te3 QL in the full frequency range. Thermal conductivity accumulation function for both freestanding and supported Bi2Te3 QL are constructed and compared. We found that half of heat transfer in freestanding Bi2Te3 QL contributed from phonons with mean free paths larger than 16.5 nm, while in supported Bi2Te3 QL this value is reduced to 11 nm. In both cases phonons with MFPs in the range of 10–30 nm are the dominate heat carriers, which contribute to 55% and 53% of thermal conductivity in freestanding and supported cases.

scholarly journals Thermal Conductivity of Defective Graphene Oxide: A Molecular Dynamic Study

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1103 ◽  
Author(s):  
Yi Yang ◽  
Jing Cao ◽  
Ning Wei ◽  
Donghui Meng ◽  
Lina Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Vacancy Defect ◽  
Vacancy Defects ◽  
Degree Of Oxidation ◽  
Non Equilibrium Molecular Dynamics ◽  
Relationship Of ◽  
Oxide Group ◽  
Dynamics Method ◽  
Group Concentration

In this paper, the thermal properties of graphene oxide (GO) with vacancy defects were studied using a non-equilibrium molecular dynamics method. The results showed that the thermal conductivity of GO increases with the model length. A linear relationship of the inverse length and inverse thermal conductivity was observed. The thermal conductivity of GO decreased monotonically with an increase in the degree of oxidation. When the degree of oxidation was 10%, the thermal conductivity of GO decreased by ~90% and this was almost independent of chiral direction. The effect of vacancy defect on the thermal conductivity of GO was also considered. The size effect of thermal conductivity gradually decreases with increasing defect concentration. When the vacancy defect ratio was beyond 2%, the thermal conductivity did not show significant change with the degree of oxidation. The effect of vacancy defect on thermal conductivity is greater than that of oxide group concentration. Our results can provide effective guidance for the designed GO microstructures in thermal management and thermoelectric applications.

scholarly journals Phonon transport and thermal conductivity of diamond superlattice nanowires: a comparative study with SiGe superlattice nanowires

RSC Advances ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 1243-1248
Author(s):  
Xilong Qu ◽  
Jinjie Gu
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Comparative Study ◽  
Molecular Dynamics Simulations ◽  
Comparative Investigation ◽  
Phonon Transport ◽  
Dynamics Simulations

We present the comparative investigation of phonon transport and thermal conductivity between diamond SLNWs and SiGe SLNWs by molecular dynamics simulations.

Influence of vacancy defects on the damage mechanics of graphene nanoribbons

2016 ◽  
Vol 26 (1) ◽  
pp. 29-49 ◽  
Author(s):  
Ji Zhang ◽  
Tarek Ragab ◽  
Cemal Basaran
Keyword(s):  
Damage Mechanics ◽  
Graphene Nanoribbons ◽  
Strain Curve ◽  
Vacancy Defect ◽  
Stress Strain Curve ◽  
Single Vacancy ◽  
Vacancy Defects ◽  
Stress Point ◽  
Dynamics Simulations ◽  
Sample Damage

Using molecular dynamics simulations, graphene nanoribbons with armchair chirality were subjected to displacement-controlled uniaxial tension until complete fracture at 300 K in order to understand their damage mechanics. Graphene nanoribbons with and without a vacancy defect were simulated to compare the effect of the defect on the fracture behavior. Simulations were performed for graphene nanoribbons with lengths ranging from 2.5 to 15 nm. The stress–strain curve of each case is reported, and the influence of defect on the material properties is discussed. For each sample, damage mechanics types were observed and discussed. Results show a negligible effect of the single vacancy defect on the ultimate strength of the graphene nanoribbon. However, having a single vacancy defect does influence the failure strain, as well as the damage mechanics past the ultimate stress point.

Role of Phonon Dispersion in Lattice Thermal Conductivity Modeling

2004 ◽  
Vol 126 (3) ◽  
pp. 376-380 ◽  
Author(s):  
J. D. Chung ◽  
A. J. H. McGaughey ◽  
M. Kaviany
Keyword(s):  
Thermal Conductivity ◽  
Relaxation Time ◽  
Lattice Thermal Conductivity ◽  
Phonon Dispersion ◽  
Phonon Relaxation Time ◽  
Dynamics Simulations ◽  
Transfer Mechanisms ◽  
Conductivity Modeling ◽  
Fitting Parameters

The role of phonon dispersion in the prediction of the thermal conductivity of germanium between temperatures of 2 K and 1000 K is investigated using the Holland approach. If no dispersion is assumed, a large, nonphysical discontinuity is found in the transverse phonon relaxation time over the entire temperature range. However, this effect is masked in the final prediction of the thermal conductivity by the use of fitting parameters. As the treatment of the dispersion is refined, the magnitude of the discontinuity is reduced. At the same time, discrepancies between the high temperature predictions and experimental data become apparent, indicating that the assumed heat transfer mechanisms (i.e., the relaxation time models) are not sufficient to account for the expected thermal transport. Molecular dynamics simulations may be the most suitable tool available for addressing this issue.

Mapping thermal resistance around vacancy defects in graphite

2013 ◽  
Vol 1543 ◽  
pp. 65-70 ◽  
Author(s):  
Laura de Sousa Oliveira ◽  
P. Alex Greaney
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
High Purity ◽  
In Silico ◽  
Large Scale ◽  
Nuclear Industry ◽  
Vacancy Defects ◽  
Dynamics Simulations ◽  
The Impact ◽  
Morphology Changes

ABSTRACTHigh purity bulk graphite is applicable in many capacities in the nuclear industry. The thermal conductivity of graphite has been found to vary as a function of how its morphology changes on the nanoscale, and the type and number of defects present. We compute thermal conductivities at the nanolevel using large scale classical molecular dynamics simulations and by employing the Green-Kubo method in a set of in silico experiments geared towards understanding the impact of defects in the thermal conductivity of graphite. We present the results obtained for systems with 1– 3 vacancies, and compile a summary of some of the methods applied and difficulties encountered.

Thermal Conductivity of Crystalline Nanoporous Silicon Using Molecular Dynamics Simulations

2011 ◽  
Author(s):  
Jin Fang ◽  
Laurent Pilon
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Effective Thermal Conductivity ◽  
Crystalline Silicon ◽  
Interfacial Area ◽  
Md Simulations ◽  
Nanoporous Silicon ◽  
Vacancy Defects ◽  
Interfacial Area Concentration ◽  
Dynamics Simulations

This study establishes that the effective thermal conductivity keff of crystalline nanoporous silicon is strongly affected not only by the porosity fv and the system’s length Lz but also by the pore interfacial area concentration Ai. The thermal conductivity of crystalline nanoporous silicon was predicted using non-equilibrium molecular dynamics (NEMD) simulations. The Stillinger-Weber potential for silicon was used to simulate the interatomic interactions. Spherical pores organized in a simple cubic lattice were introduced in a crystalline silicon matrix by removing atoms within selected regions of the simulation cell. Effects of the (i) system length ranging from 13 to 130 nm, (ii) pore diameter varying between 1.74 and 5.86 nm, and (iii) porosity ranging from 8% to 38%, on thermal conductivity were investigated. A physics-based model was also developed by combining kinetic theory and the coherent potential approximation. The effective thermal conductivity was proportional to (1–1.5fv) and inversely proportional to the sum (Ai/4+1/Lz). This model was in excellent agreement with the thermal conductivity of nanoporous silicon predicted by MD simulations for spherical pores (present study) as well as for cylindrical pores and vacancy defects reported in the literature. These results will be useful in designing nanostructured materials with desired thermal conductivity by tuning their morphology.

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