Anharmonicity in elastic constants and extended x-ray-absorption fine structure cumulants

Yokoyama, Toshihiko; Chaveanghong, Suwilai

doi:10.1103/physrevmaterials.3.033607

Cited by 13 publications

(15 citation statements)

References 43 publications

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“…S 0 2 and Δ E 0 were determined at the lowest temperature (20 K) and then fixed for all other temperatures (as done by others in temperature-dependent studies of EXAFS Debye–Waller factors) . Δ E 0 and S 0 2 can influence the absolute values of R EXAFS , C 2 , and C 3 .…”

Section: Resultsmentioning

confidence: 99%

“…For the analysis of the Artemis Fit results, we used the relative values Δ C 3 with respect to the lowest temperature for the temperature-dependent C 3 cumulants, as we did for R EXAFS and C 2 . Δ C 3 was fitted by a simplified version of the classical approximation for cumulants valid for higher temperatures , Here, k B (eV·K –1 ) is the Boltzmann constant, k 0 is the effective (harmonic) force constant determined with C 2 ( T ), and k 3 (eV Å –3 ) is the higher-order (anharmonic) force constant. According to Frenkel et al, our used approximation for higher temperatures for C 3 ( T ) is already valid for RbBr at 125 K so that we can assume that an adjustment of Δ C 3 in the orthorhombic phases (up to 160 K) is also meaningful.…”

Section: Resultsmentioning

confidence: 99%

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Temperature-Dependent EXAFS Measurements of the Pb L3-Edge Allow Quantification of the Anharmonicity of the Lead–Halide Bond of Chlorine-Substituted Methylammonium (MA) Lead Triiodide

et al. 2022

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This article reports on studies of chlorine-substituted MAPbI 3 using combined temperature-dependent X-ray diffraction (XRD) synchrotron and Pb-L3 edge extended X-ray absorption fine structure (EXAFS) to analyze the anharmonicity of the lead−halide bond. The EXAFS parameters were described in the orthorhombic phase by an Einstein or T 2 -type behavior, which was then compared with the experimental EXAFS parameters of the tetragonal/cubic phase. In the orthorhombic phase, it was observed that the asymmetry of the pair distribution function (cumulant C 3 ) in MAPbCl 3 is much lower than in MAPbI 3 . Compared with the behavior in the orthorhombic phase, the anharmonicity changed after the phase transition to the roomtemperature phase, with MAPbCl 3 showing an increased anharmonicity and MAPbI 3 a decrease. The differences between MAPbI 3 and 2% chlorine substitution were small, both in the orthorhombic and tetragonal phases. By determining the structural parameters required to convert the effective force constants k 0 and k 3 resulting from the EXAFS analysis into the Morse potential parameters α and D, we could establish that our results agree with other experimental findings. Moreover, using XRD, we found that the [PbX 6 ] octahedra appear to shrink slightly in the tetragonal phase of MAPbI 3 and MAPbI 2.94 Cl 0.06 , toward increasing temperatures. This behavior in the tetragonal phase is related to the dominant negative tension effects observed by EXAFS.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Temperature-Dependent EXAFS Measurements of the Pb L3-Edge Allow Quantification of the Anharmonicity of the Lead–Halide Bond of Chlorine-Substituted Methylammonium (MA) Lead Triiodide

et al. 2022

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“…At the end of this section, the interatomic potentials around Fe are summarized in Figure 8 to compare between the three different Fe-based alloys of the Invar (Fe 65 Ni 35 ), SUS316L (Fe 67 Cr 18 Ni 12 Mo 2 Mn 1 ) [47] , and Elinvar (Fe 50 Ni 42 Cr 6 Ti 4 ) [34] alloys. The stainless steel SUS316L alloy exhibits normal thermal expansion that is quantitatively almost the same as that of SUS304 in Figure 4A.…”

Section: Invar Alloymentioning

confidence: 99%

“…alloys. FM and NM denote the ferromagnetically coupled high-spin and nonmagnetic low-spin Fe, respectively [47] .…”

Section: Zinc Blendementioning

confidence: 99%

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Thermal expansion of FeNi Invar and zinc-blende CdTe from the view point of local structure

Yokoyama¹

2021

Microstructures

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Thermal expansion of FeNi Invar and zinc-blende CdTe was investigated from the view point of local structure using the extended x-ray absorption fine structure (EXAFS) spectroscopic data and the path-integral effective classical potential (PIECP) Monte Carlo computational simulations. In this Review article, first the quantum statistical perturbation theory is intuitively described to see different character concerning thermal expansion between the quantum and classical theories. The diatomic Br 2 molecule is employed as a simple example. Second, the PIECP theory is briefly described to note advantages and disadvantages of this simulation technique. Historical background is also discussed for the EXAFS investigation of thermal expansion based on the quantum statistical theories. The results of the FeNi Invar alloy are then summarized. The origin of zero thermal expansion in the FeNi alloy is ascribed to the so-called Invar effect that implies the variation of the electronic structure of Fe atoms depending on temperature. Zero thermal expansion at low temperature is however found to originate from the vibrational quantum effect. It is also noted that the interatomic distances of Fe-Fe, Fe-Ni, and Ni-Ni pairs are slightly but meaningfully different from each other, although the alloy exhibit a simple fcc crystal. Such a pairdependent difference is also true for thermal expansion and we will discuss thermal expansion from the local point of view, which is interestingly different from the lattice thermal expansion significantly. Finally, the results of the zinc blende (or diamond) structure are presented. Although the origin of negative thermal expansion in these tetrahedral crystals is known as a result of classical vibrational anomaly within the Newton dynamics theory, the quantum statistical simulation is found to be essential to reproduce the negative thermal expansion of CdTe. It is emphasized that the vibrational quantum effect and classical anharmonicity are of great importance for the understanding of low-temperature thermal expansion as well as the elastic constants.

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Investigation of anharmonic EXAFS parameters of Ag using anharmonic correlated Debye model under the effect of thermal disorders

Tien,

Manh,

Thuy

et al. 2024

Solid State Communications

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Anharmonicity in elastic constants and extended x-ray-absorption fine structure cumulants

Cited by 13 publications

References 43 publications

Temperature-Dependent EXAFS Measurements of the Pb L3-Edge Allow Quantification of the Anharmonicity of the Lead–Halide Bond of Chlorine-Substituted Methylammonium (MA) Lead Triiodide

Temperature-Dependent EXAFS Measurements of the Pb L3-Edge Allow Quantification of the Anharmonicity of the Lead–Halide Bond of Chlorine-Substituted Methylammonium (MA) Lead Triiodide

Thermal expansion of FeNi Invar and zinc-blende CdTe from the view point of local structure

Investigation of anharmonic EXAFS parameters of Ag using anharmonic correlated Debye model under the effect of thermal disorders

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