Lattice Vibrations

Schober, H. R.; Petry, W.

doi:10.1002/9783527603978.mst0005

Cited by 6 publications

(5 citation statements)

References 88 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The acoustic part was modeled by scaling both DPS (n‐Si and n‐Ge) to an effective elastic medium average of

{Si}_{80} {Ge}_{20}

which reproduces the speed of sound. The optical part was modeled by considering the same electronic structure and applying a homology relation () with which the mode energy difference can be calculated as

E_{{Si}_{80} {Ge}_{20}} / E_{Si} = \sqrt{false(M_{Si} a_{Si}^{2} false) / false(M_{{Si}_{80} {Ge}_{20}} a_{{Si}_{80} {Ge}_{20}}^{2} false)}

. The same relation was used for Ge, and the resulting scale factors are

E_{{Si}_{80} {Ge}_{20}} / E_{Si} = 0.87

and

E_{{Si}_{80} {Ge}_{20}} / E_{Ge} = 1.45

.…”

Section: Resultsmentioning

confidence: 99%

Lattice dynamics and thermoelectric properties of nanocrystalline silicon–germanium alloys

Claudio

Stein

Petermann

et al. 2015

Physica Status Solidi (a)

View full text Add to dashboard Cite

The lattice dynamics and thermoelectric properties of sintered phosphorus‐doped nanostructured silicon–germanium alloys obtained by gas‐phase synthesis were studied. Measurements of the density of phonon states by inelastic neutron scattering were combined with measurements of the elastic constants and the low‐temperature heat capacity. A strong influence of nanostructuring and alloying on the lattice dynamics was observed. The thermoelectric transport properties of samples with different doping as well as samples sintered at different temperature were characterized between room temperature and 1000°C. A peak figure of merit italiczT=0.88 at 900°C is observed and is comparatively insensitive to the aforementioned parameter variations.

show abstract

“…The acoustic part was modeled by scaling both DPS (n‐Si and n‐Ge) to an effective elastic medium average of

{Si}_{80} {Ge}_{20}

E_{{Si}_{80} {Ge}_{20}} / E_{Si} = \sqrt{false(M_{Si} a_{Si}^{2} false) / false(M_{{Si}_{80} {Ge}_{20}} a_{{Si}_{80} {Ge}_{20}}^{2} false)}

. The same relation was used for Ge, and the resulting scale factors are

E_{{Si}_{80} {Ge}_{20}} / E_{Si} = 0.87

and

E_{{Si}_{80} {Ge}_{20}} / E_{Ge} = 1.45

.…”

Section: Resultsmentioning

confidence: 99%

Lattice dynamics and thermoelectric properties of nanocrystalline silicon–germanium alloys

Claudio

Stein

Petermann

et al. 2015

Physica Status Solidi (a)

View full text Add to dashboard Cite

show abstract

“…The Si contribution to the density of phonon states shows a sharp peak at around 36 meV instead of the analoguous peak in Ge contribution which appears at around 18 meV. Assuming the same force constants, the mass homology relation, [42], should fully describe the mode energy difference. The mass ratio is √ M Ge /M Si = 1.61 and the lattice constants ratio is a Mg 2 Ge /a Mg 2 Si = 1.005 at room temperature, hence, E Si /E Ge = 1.616.…”

Section: Discussionmentioning

confidence: 98%

Lattice dynamics in intermetallic Mg₂Ge and Mg₂Si

Bessas¹,

Simon²,

Friese³

et al. 2014

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

The lattice dynamics of polycrystalline Mg(2)Ge and Mg(2)Si are compared using both microscopic and macroscopic measurements as well as theoretical calculations. The volume thermal expansion coefficient between 200 and 300 K was found to be 4.37(5) · 10(-5) K(-1) in Mg(2)Ge, compared to 3.69(5) · 10(-5) K(-1) in Mg(2)Si. Inelastic neutron scattering measurements yield densities of phonon states which are in line with theoretical calculations. The microscopic data were corroborated with macroscopic calorimetry measurements and provide quantified values for anharmonicity. The estimated macroscopic Grüneisen parameter is, γ(Mg(2)Si) = 1.17(5) and γ(Mg(2)Ge) = 1.46(5) at 295 K, in excellent agreement with Raman scattering data. Although the element specific mean force constants are practically the same, in Mg(2)Ge and Mg(2)Si, a mass homology relation alone cannot reproduce the difference in the partial densities of vibrational states in these compounds and differences in elemental bonding should be taken into account.

show abstract

“…Although the Mn to Fe ratio drastically changes the magnetic order in (Mn,Fe) 3 Si it hardly affects the lattice dynamics. The mass homology relation in isostructural systems indicates that the energy of the vibrational modes varies as a function of the lattice parameters ratio and the nuclear mass ratio [37]. The nuclear masses of Mn and Fe are practically the same.…”

Section: A the Impurity Phasementioning

confidence: 99%

Lattice dynamics across the magnetic transition in(Mn,Fe)1.95(P,Si)

et al. 2018

View full text Add to dashboard Cite

The lattice dynamics in MnFe 0.95 Si 0.50 P 0.50 were investigated experimentally using 57 Fe nuclear inelastic scattering and inelastic x-ray scattering across the first-order magnetic transition which occurs close to room temperature. The lattice dynamics characterization was supported by a macroscopic magnetic characterization, an x-ray diffraction study, and a hyperfine interactions characterization using Mössbauer spectroscopy. The Fe specific and the x-ray generalized density of phonon states were obtained both in the ferromagnetic and in the paramagnetic state. A prominent shift, 2 meV at 20 meV, in the x-ray generalized density of phonon states across the first-order magnetic transition, that involves vibrations with essentially Fe character, is revealed corroborated by a change in the local environment quantified in the isomer shift and the quadrupole splitting. Above 35 meV the vibrational modes are practically insensitive to the magnetic transition. The entropy change induced by a 1 T magnetic field across the magnetic transition, ∼10 J/K/kg, is only a fraction of the Fe vibrational entropy change, 62(21) J/K/kg.

show abstract

Lattice Vibrations

Cited by 6 publications

References 88 publications

Lattice dynamics and thermoelectric properties of nanocrystalline silicon–germanium alloys

Lattice dynamics and thermoelectric properties of nanocrystalline silicon–germanium alloys

Lattice dynamics in intermetallic Mg₂Ge and Mg₂Si

Lattice dynamics across the magnetic transition in(Mn,Fe)1.95(P,Si)

Contact Info

Product

Resources

About

Lattice Vibrations

Cited by 6 publications

References 88 publications

Lattice dynamics and thermoelectric properties of nanocrystalline silicon–germanium alloys

Lattice dynamics and thermoelectric properties of nanocrystalline silicon–germanium alloys

Lattice dynamics in intermetallic Mg2Ge and Mg2Si

Lattice dynamics across the magnetic transition in(Mn,Fe)1.95(P,Si)

Contact Info

Product

Resources

About

Lattice dynamics in intermetallic Mg₂Ge and Mg₂Si