相关论文: Anharmonic Phonons and Anomalous Thermal Expansion…

Anomalous thermal expansion behaviour of several open frame-work compounds has been extensively investigated using the techniques of inelastic neutron scattering and lattice dynamics. These compounds involve increasing level of structural…

In order to identify and quantitatively analyze the anharmonicity of phonons relevant to the anomalous thermal expansion in the Ih phase of ice, we performed neutron inelastic scattering measurements of the phonon spectrum as a function of…

The thermal expansion behavior of metal fluorides can be tuned by choosing appropriate metal cation. We present ab-initio lattice dynamical studies on the metal fluorides (CaZrF6, MgZrF6 and SrZrF6) and identify the anharmonic phonon modes…

Zn(CN)2 is known to have an isotropic negative thermal expansion (NTE) coefficient (about -51 x 10-6 K-1) over 10-370 K that is twice as large as that of ZrW2O8. We have measured the pressure dependence of the phonon spectra up to 30 meV…

Heat conduction in graphite has been studied for decades because of its exceptionally large thermal anisotropy. While the bulk thermal conductivities along the in-plane and cross-plane directions are well known, less understood are the…

The thermal and lattice dynamical properties of seven silicon clathrate framework structures are investigated with ab initio density functional methods (frameworks I, II, IV, V, VII, VIII, and H). The negative thermal expansion (NTE)…

We investigate detailed lattice dynamics of copper halides CuX (X=Cl, Br, I) using neutron inelastic scattering measurements and ab-initio calculations aimed at a comparative study of their thermal expansion behavior. We identify the low…

An anisotropic lattice anomaly near the superconducting transition temperature, Tc, was observed in MgB2 by high-resolution neutron powder diffraction. The a-axis thermal expansion becomes negative near Tc, while the c-axis thermal…

Metal Chalcogenides have been known for important technological applications and have attracted continuous interest in their structure, electronic, thermal and transport properties. Here we present first principles calculations of the…

We report ab-inito density functional theory calculation of phonons in cubic phase of ZrW2O8 in the entire Brillouin zone and identify specific anharmonic phonons that are responsible for large negative thermal expansion (NTE) in terms of…

Graphene and its derivatives distinguish themselves for their large negative thermal expansion even at temperatures as high as 1000K. The linear thermal expansion coefficients (LTEC) of two-dimensional honeycomb structured pure graphene and…

Understanding the microscopic processes affecting the bulk thermal conductivity is crucial to develop more efficient thermoelectric materials. PbTe is currently one of the leading thermoelectric materials, largely thanks to its low thermal…

We use first-principles theory to show that the ingredients assumed to be essential to the occurrence of negative thermal expansion (NTE) -- rigid unit phonon modes with negative Gr\"{u}neisen parameters -- are neither sufficient nor…

In two-dimensional materials, structure difference induces the difference in phonon dispersions, leading to the anisotropy of in-plane thermal transport. Here, we report an exceptional case in layered PdSe2, where the bonding, force…

Beta eucryptite (LiAlSiO4) shows one-dimensional super-ionic conductivity as well as anisotropic thermal expansion behavior. We have performed inelastic neutron scattering measurements in beta eucryptite over 300 to 900 K and calculated the…

All phonons in a single crystal of NaBr were measured by inelastic neutron scattering at temperatures of 10, 300 and 700 K. Even at 300 K the phonons, especially the longitudinal-optical (LO) phonons, showed large shifts in frequencies, and…

Recently colossal positive volume thermal expansion has been found in the framework compounds Ag3Co(CN)6 and Ag3Fe(CN)6. Phonon spectra have been measured using the inelastic neutron scattering technique as a function of temperature and…

We present the results of inelastic x-ray scattering for magnetite and analyze the energies and spectral widths of the phonon modes with different symmetries in a broad range of temperature 125<T<293 K. The phonon modes with X_4 and Delta_5…

We report measurement of temperature dependence of phonon spectra in quasi one-dimensional metal cyanides MCN (M=Cu, Ag and Au). Ab initio lattice dynamics calculations have been performed to interpret the phonon-spectra as well as to…

Allotropes of carbon, such as diamond and graphene, are among the best conductors of heat. We monitored the evolution of thermal conductivity in thin graphite as a function of temperature and thickness and found an intimate link between…