共查询到20条相似文献,搜索用时 12 毫秒
1.
《中国物理 B》2016,(11)
Metallic nanofilms are important components of nanoscale electronic circuits and nanoscale sensors.The accurate characterization of the thermophysical properties of nanofilms is very important for nanoscience and nanotechnology.Currently,there is very little specific heat data for metallic nanofilms,and the existing measurements indicate distinct differences according to the nanofilm size.The present work reports the specific heats of 40-nm-thick suspended platinum nanofilms at 80-380 K and ~5 ×10~(-4) Pa using the 3 ω method.Over 80-380 K,the specific heats of the Pt nanofilms range from 166-304 J/(kg·K),which are 1.65-2.60 times the bulk values,indicating significant size effects.These results are useful for both scientific research in nanoscale thermophysics and evaluating the transient thermal response of nanoscale devices. 相似文献
2.
3.
The electronic specific heat of nanographite ribbons exhibits rich temperature dependence, mainly owing to the special band structures. The thermal property strongly depends on the geometric structures, the edge structure and the width. There is a simple relation between the ribbon width and the electronic specific heat for the metallic or semiconducting armchair ribbons. However, it is absent for the zigzag ribbons. The metallic armchair ribbons exhibit linear temperature dependence. The semiconducting armchair ribbons exhibit composite behavior of power and exponential functions. As for the zigzag ribbons, the temperature dependence of the specific heat is proportional to T1−p. The value of p quickly increases from
to 1 as the ribbon width gradually grows. The zigzag ribbons might be the first system which exhibits the novel temperature dependence. The nanographite ribbons differ from an infinite graphite sheet, which illustrates that the finite-size effects are significant. 相似文献
4.
5.
Abstract We have obtained new data of the low-temperature specific heat of CeAl2 under pressure with the aim to complete the phase diagram and to solve an existing discrepancy between results of magnetic and thermodynamic measurements. 相似文献
6.
In this article, we studied the specific heat data of iron-based superconductors LaO1? x F x FeAs (x?=?0.1) and SmO1? x F x FeAs (x?=?0.13,?0.12, and 0.1). (i) The contribution of phonons in specific heat above Tc depends exponentially on temperature. (ii) The specific heat has different contributions, and they change differently at Tc . This change must be the effect of a physical function on heat capacity. Therefore, transition temperature is defined by thermal parameters. For LaO0.9F0.1FeAs and SmO0.87F0.13FeAs, a transition point was evaluated at 22.11 and 26.32?K, respectively. This is in close agreement with the midpoint transition temperatures obtained from dc resistivity and magnetization experiments, where the modified electronic heat capacity led to the approximate value of the transition point in two samples. The jump, ΔC/γT c, and the electronic and lattice heat capacity coefficients, γ and β, respectively, were evaluated. 相似文献
7.
R.G. Sarmento G.A. Mendes E.L. Albuquerque U.L. Fulco M.S. Vasconcelos O. Ujsághy V.N. Freire E.W.S. Caetano 《Physics letters. A》2012
The electronic specific heat spectra at constant volume (CV) of a long-range correlated extended ladder model, mimicking a DNA molecule, is theoretically analyzed for a stacked array of a double-stranded structure made up from the nucleotides guanine G, adenine A, cytosine C and thymine T . The role of the aperiodicity on CV is discussed, considering two different nucleotide arrangements with increasing disorder, namely the Fibonacci and the Rudin–Shapiro quasiperiodic structures. Comparisons are made for different values of the band fillings, considering also a finite segment of natural DNA, as part of the human chromosome Ch22. 相似文献
8.
9.
对电流量热器法测定液体比热容实验的改进 总被引:1,自引:0,他引:1
考虑两个量热器的电阻不相等,推导出液体比热容的计算公式。不必交换电阻重测,按m2≈m1c1/c2称比较液体的质量,可以使两种液体的升温大致相等,散热条件基本相同。 相似文献
10.
11.
12.
M.T. Borowiec V.P. Dyakonov A. Szewczyk M.U. Gutowska T. Zayarnyuk E.E. Zubov 《Phase Transitions》2013,86(11-12):944-951
The results of measurements of thermal properties (specific heat) of potassium holmium double tungstate KHo(WO4)2 as a function of temperature (from 0.5 to 300?K) and magnetic field (up to 2?T) are presented. The total specific heat without the phonon and Schottky contributions is found to have the anomaly with maximum at T SPT?~?5?K. This anomaly is likely related with the structural phase transition (SPT) caused by the cooperative Jahn–Teller effect. The increase of specific heat at very low temperatures and its shift towards high temperatures with increasing magnetic field are observed. The origin of this behaviour can be connected with possible magnetic phase transition induced by magnetic field. 相似文献
13.
The tight-binding model including curvature effects is used to study the effect of transverse electric field on the low-temperature electronic specific heat (Cv) for armchair and zigzag carbon nanotubes (ACNTs and ZCNTs). Electric field could effectively modulate energy dispersions of CNTs and cause a shift of electronic states toward the Fermi energy. As field strength reaches to a critical value (Fc), it induces special structures in the density of states near the Fermi energy and thus the giant specific heat. At Fcs, Cv has a value comparable to that of the phonon specific heat and reveals strongly non-linear dependence on temperature. The critical field strength and giant specific heat are closely related to nanotube's geometry. Moreover, under Fcs, the extra longitudinal magnetic flux could cause a re-enhancement in Cv for ZCNTs, whereas Cv is always diminished for ACNTs. 相似文献
14.
YIN Xue-Ai LUO Bo LIU Fei YI Lin 《理论物理通讯》2007,48(4):745-748
With the help of the elastic wave theory in the perturbed approximation the density-of-states for vibrational modes and the specific heat are studied for different hollow Si nanospheres, coupled with a semi-infinite substrate. We find that the modes of such coupled hollow spheres are significantly broadened and shifted toward low frequencies. The specific heat of the coupled hollow nanosphere is bigger than an isolated one due to the coupling interaction and quantum size effects. The predicted coupling and size enhancements on specific heat are probed in thermal experiments. 相似文献
15.
Using the Embedding Atom Method (EAM) for highly undercooled Ni3Al alloy, the melting point and the specific heat were studied by a molecular dynamics simulation. The simulation of melting
point was carried out by means of the sandwich method and the NVE ensemble method, and the results show a good agreement,
whereas are larger than the experimental value of 1663 K. This difference is attributed to the influence of surface melting
on experimental results, which causes the smaller measurements compared with the thermodynamic melting point. The simulated
specific heat of Ni3Al alloy weakly and linearly increases with the increase of undercooling in the temperature range from 800 K to 2000 K.
Supported by the National Natural Science Foundation of China (Grant No. 50395101) 相似文献
16.
17.
Superconducting thermal fluctuation(STF) plays an important role in both thermodynamic and transport properties in the vortex liquid phase of high T_c superconductors.It was widely observed in the vicinity of the critical transition temperature.In the framework of Ginz burg-Landau-La wrence-Doniach theory in magnetic field,a self-consistent analysis of STF including all Landau levels is given.Besides that,we calculate the contribution of STF to specific heat in vortex liquid phase for high T_c cuprate superconductors,and the fitting results are in good agreement with experimental data. 相似文献
18.
水的比汽化热测量装置的改进 总被引:1,自引:1,他引:0
对传统的测量水的比汽化热实验中的加热和输气装置进行改进,采用集成电路温度传感器测量量热器中温度,实现了水比汽化热非电量电测,较准确地测量水的比汽化热. 相似文献
19.
20.
Floating zone growth and magnetic and specific heat properties of La0.67Ca0.33Mn1-xFexO3(x=0.00,0.04)single crystals 下载免费PDF全文
Single crystals of La0.67Ca0.33MnO3 and La0.67Ca0.33Mn0.96Fe0.04O3 were obtained by floating zone method. Laue diffraction pattern and rocking curve of the single crystals show that their quality is good. The magnetic behaviours of these compounds have been studied. Fe doping significantly depresses the magnetic contribution to the total specific heat CP, but slightly influences the lattice contribution at temperatures above 50K. The peak of CP shifts towards high temperatures with increasing magnetic field. Both single crystals exhibit the first-order magnetic transition around the Curie temperature. 相似文献