scispace - formally typeset
Search or ask a question
Topic

Debye model

About: Debye model is a research topic. Over the lifetime, 7462 publications have been published within this topic receiving 133987 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: The similarity of these findings with the graphene/Ru(0001) system indicates that the bonding of graphene to a metal substrate alters the dynamic properties of the graphene surface strongly and is responsible for the high helium reflectivity of these systems.
Abstract: Using helium atom scattering, we have studied the structure and dynamics of a graphene layer prepared in situ on a Ni(111) surface. Graphene/Ni(111) exhibits a helium reflectivity of ∼20% for a thermal helium atom beam and a particularly small surface electron density corrugation ((0.06 ± 0.02) A peak to peak height). The Debye-Waller attenuation of the elastic diffraction peaks of graphene/Ni(111) and Ni(111) was measured at surface temperatures between 150 and 740 K. A surface Debye temperature of θD = (784 ± 14) K is determined for the graphene/Ni(111) system and θD = (388 ± 7) K for Ni(111), suggesting that the interlayer interaction between graphene and the Ni substrate is intermediary between those for strongly interacting systems like graphene/Ru(0001) and weakly interacting systems like graphene/Pt(111). In addition we present measurements of low frequency surface phonon modes on graphene/Ni(111) where the phonon modes of the Ni(111) substrate can be clearly observed. The similarity of these findings with the graphene/Ru(0001) system indicates that the bonding of graphene to a metal substrate alters the dynamic properties of the graphene surface strongly and is responsible for the high helium reflectivity of these systems.

53 citations

Journal ArticleDOI
TL;DR: In this article, the thermal relaxation method was used to measure the specific heat of BaPb 1-x Bi x O 3 at low temperatures, and it was shown that the electronic specific heat coefficient increased with x until x = 0.25 and then decreased above, corresponding to the composition dependence of T c.
Abstract: Specific heat coefficient of BaPb 1- x Bi x O 3 at low temperatures was measured by the thermal relaxation method. Although the discontinuity in the specific heat C at the superconducting transition temperature T c could not be detected, it was clearly observed in the lowest experimental temperature region that C in the superconducting state at zero magnetic field was smaller than in the normal state at H =59 kOe. The electronic specific heat coefficient γ increased with x until x =0.25 and then decreased above, corresponding to the composition dependence of T c . However, the γ value, e.g. 1.6 mJ mole -1 K -2 at x =0.25, was one to two orders of magnitude smaller than those of the other typical high T c superconducting metals. The Debye temperature was in the range 166 K to 196 K for 0 ≤ x ≤0.3.

53 citations

Journal ArticleDOI
TL;DR: In this paper, the authors measured the acoustic velocities of Pd39Ni10Cu30P21 bulk metallic glass (BMG) by an ultrasonic technique upon annealing.
Abstract: Acoustic velocities of Pd39Ni10Cu30P21 bulk metallic glass (BMG) are measured by an ultrasonic technique upon annealing. The elastic constants and the Debye temperature are obtained. A large softening of the transverse phonon is exhibited in the as-quenched BMG relative to its crystallized state. Upon crystallization, the shear modulus and the Debye temperature increase by ∼30% and ∼12%, respectively; however, the density increases by only ∼0.6%. Some anomalous acoustic and elastic behaviors are observed near the glass transition temperature and in the supercooled liquid region of the BMG. The anomalies are explained with regard to the structural changes.

53 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of temperature on thermal properties of monolayer MoS2 were investigated using first-principles calculations based on the density-functional perturbation theory.

53 citations

Journal ArticleDOI
TL;DR: In this article, the electrical properties of mixed CaO and BaO glasses were studied in the frequency range 400 Hz-200 kHz and over a temperature range 323-593 K.
Abstract: The electrical properties of xCaO-(20 - x)BaO-20Fe 2 O 3 -60P 2 O 5 glasses with x = 0, 5, 10, 15 and 20 mol% have been studied in the frequency range 400 Hz-200 kHz and over a temperature range 323-593 K. The ac conductivity as a function of temperature was divided into two domains, one where the absolute magnitude of the ac conductivity was close to the dc conductivity and another where it was larger than the dc conductivity. At the same temperature, the dc conductivity varied only slightly in glasses with different CaO and BaO content. It is concluded that the conductivity in these mixed CaO and BaO iron phosphate glasses is electronic and depends upon the Fe 2+ /(Fe 2+ + Fe 3+ ) ratio. In the high-temperature region above θ D /2 (where θ D is the Debye temperature) the Mott model of small polaron hopping (SPH) between nearest neighbours is consistent with the conductivity data, while at low temperature (below θ D ) the Greaves intermediate variable-range hopping (VRH) model is found to be appropriate. The electrical conduction of the glasses is confirmed to be non-adiabatic SPH. Mossbauer spectral analysis indicates the presence of both Fe 2+ and Fe 3+ ions.

53 citations


Network Information
Related Topics (5)
Magnetization
107.8K papers, 1.9M citations
92% related
Band gap
86.8K papers, 2.2M citations
92% related
Amorphous solid
117K papers, 2.2M citations
90% related
Thin film
275.5K papers, 4.5M citations
90% related
Raman spectroscopy
122.6K papers, 2.8M citations
87% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023178
2022346
2021303
2020242
2019285
2018304