Scattering of Neutrons by an Anharmonic Crystal

Maradudin, A. A.; Fein, A. E.

doi:10.1103/physrev.128.2589

Cited by 893 publications

(452 citation statements)

References 15 publications

Supporting

Mentioning

439

Contrasting

Unclassified

Order By: Relevance

“…By applying Fermi's golden rule to the cubic Hamiltonian [50][51][52][53], the phonon lifetimes s q τ due to the normal and umklapp three-phonon scattering processes can be expressed as …”

Section: B Anharmonic Propertiesmentioning

confidence: 99%

Phonon conduction in PbSe, PbTe, and PbTe1−xSexfrom first-principles calculations

et al. 2012

View full text Add to dashboard Cite

We apply first-principles calculations to lead selenide (PbSe) and lead telluride (PbTe) and their alloys (PbTe 1-x Se x ) which are potentially good thermoelectric materials, to investigate their phonon transport properties. By accurately reproducing the lattice thermal conductivity, we validate the approaches adopted in this work. We then compare and contrast PbSe and PbTe, evaluate the importance of the optical phonons to lattice thermal conductivity, and estimate the impacts of nanostructuring and alloying on further reducing the lattice thermal conductivity. The results indicate that: 1) the optical phonons are important not only because they directly comprise over 20% of the lattice thermal conductivity, but also because they provide strong scattering channels for acoustic phonons, which is crucial for the low thermal conductivity; 2) nanostructures of less than ~10 nm are needed to reduce the lattice thermal conductivity for pure PbSe and PbTe; 3) alloying should be a relatively effective way to reduce the lattice thermal conductivity.

show abstract

“…By applying Fermi's golden rule to the cubic Hamiltonian [50][51][52][53], the phonon lifetimes s q τ due to the normal and umklapp three-phonon scattering processes can be expressed as …”

Section: B Anharmonic Propertiesmentioning

confidence: 99%

Phonon conduction in PbSe, PbTe, and PbTe1−xSexfrom first-principles calculations

et al. 2012

View full text Add to dashboard Cite

show abstract

“…3, we will show later on that there are, in fact, deviations larger than the error bars. At temperatures in the vicinity of absolute zero, due to the low occupation of vibrational modes, phonons behave as weakly interacting quasiparticles that can be treated within the harmonic approximation [58]. In this limit, characteristic frequencies of the phonons are well defined and the lifetimes are practically infinite.…”

Section: A Vibrational Excitationsmentioning

confidence: 99%

“…As the temperature is increased, phonon occupation numbers also increase, which in turn increases the probability of mutual interactions. As a result of such phonon-phonon scattering at elevated temperatures, characteristic frequencies of the phonons may shift, and the lifetimes may shorten [58,59]. In magnetic crystals, the co-existence of phonons and magnons gives rise to another class of scattering processes, namely, phonon-magnon scattering.…”

Section: A Vibrational Excitationsmentioning

confidence: 99%

Collective dynamics in atomistic models with coupled translational and spin degrees of freedom

et al. 2017

View full text Add to dashboard Cite

Using an atomistic model that simultaneously treats the dynamics of translational and spin degrees of freedom, we perform combined molecular and spin dynamics simulations to investigate the mutual influence of the phonons and magnons on their respective frequency spectra and lifetimes in ferromagnetic bcc iron. By calculating the Fourier transforms of the space-and time-displaced correlation functions, the characteristic frequencies and the linewidths of the vibrational and magnetic excitation modes were determined. Comparison of the results with that of the standalone molecular dynamics and spin dynamics simulations reveal that the dynamic interplay between the phonons and magnons leads to a shift in the respective frequency spectra and a decrease in the lifetimes. Moreover, in the presence of lattice vibrations, additional longitudinal magnetic excitations were observed with the same frequencies as the longitudinal phonons.

show abstract

“…The lattice potential energy of a solid is, in general, anharmonic (Maradudin & Fein 1962;Cowley 1963). The anharmonicity has, in principle, two main effects on the solid and its spectral properties: thermal expansion of the solid and interactions of phonons of different modes influence their energy and give them a finite lifetime (the reciprocal counterpart to the damping).…”

Section: Theoretical Point Of Viewmentioning

confidence: 99%

“…However, in many cases g j can be assumed as a constant value ranging between 0 and 2 (Lowndes 1970;Gervais & Piriou 1975), in which case δω j will show a quadratic temperature dependence. The phonon-interaction contribution to the frequency shift Δω PI j has been determined by Maradudin & Fein (1962) and by Cowley (1963) involving three phonon processes to secondorder and four phonon processes to first-order pertubation theory. With their assumptions, they obtain a linear temperature dependence of the frequency shift in the high-temperature limit.…”

Section: Theoretical Point Of Viewmentioning

confidence: 99%

Optical constants of refractory oxides at high temperatures

Zeidler

Posch

Mutschke

2013

A&A

View full text Add to dashboard Cite

Context. Many cosmic dust species, among them refractory oxides, form at temperatures higher than 300 K. Nevertheless, most astrophysical studies are based on the room-temperature optical constants of solids, such as corundum and spinel. A more realistic approach is needed for these materials, especially in the context of modeling late-type stars. Aims. We aimed at deriving sets of optical constants of selected, astrophysically relevant oxide dust species with high melting points. Methods. A high-temperature, high-pressure cell and a Fourier-transform spectrometer were used to measure reflectance spectra of polished samples. For corundum (α-Al 2 O 3 ), spinel (MgAl 2 O 4 ), and α-quartz (SiO 2 ), temperature-dependent optical constants were measured from 300 K up to more than 900 K. Small particle spectra were also calculated from these data. Results. All three examined oxides show a significant temperature dependence of their mid-IR bands. For the case of corundum, we find that the 13 μm emission feature -seen in the IR spectra of many AGB stars -can very well be assigned to this mineral species. The best fit of the feature is achieved with oblate corundum grains at (mean) temperatures around 550 K. Spinel remains a viable carrier of the 13 μ feature as well, but only for T < 300 K and nearly spherical grain shapes. Under such circumstances, spinel grains may also account for the 31.8 μm band that is frequently seen in sources of the 13 μm feature and which has not yet been identified with certainty.

show abstract

Scattering of Neutrons by an Anharmonic Crystal

Cited by 893 publications

References 15 publications

Phonon conduction in PbSe, PbTe, and PbTe1−xSexfrom first-principles calculations

Phonon conduction in PbSe, PbTe, and PbTe1−xSexfrom first-principles calculations

Collective dynamics in atomistic models with coupled translational and spin degrees of freedom

Optical constants of refractory oxides at high temperatures

Contact Info

Product

Resources

About