Specific heat below 3 °K, melting point, and melting heat of rubidium and cesium

1970 ◽  
Vol 48 (11) ◽  
pp. 1327-1339 ◽  
Author(s):  
Douglas L. Martin
Keyword(s):  
Thermal Analysis ◽  
Melting Point ◽  
Low Temperature ◽  
Specific Heat ◽  
Alkali Metals ◽  
Effective Masses ◽  
Debye Temperatures ◽  
Latent Heat Of Melting ◽  
Specific Heat Coefficient ◽  
Limiting Value

Specific heat measurements were made between 0.4 and 3.0 °K. For rubidium (nominal purity 99.9%, actual purity probably ~ 99.99%) the electronic specific heat coefficient γ is 624.6 ± 6.5 μcal/°K2 g atom and the low temperature limiting value of the Debye temperature (ΘOoc) is 56.5 ± 0.2 °K. For cesium (nominal purity 99.99%, actual purity probably ~ 99.97%) γ is 950 ± 20 μcal/°K2 g atom and ΘOoc is 40.5 ± 0.3 °K. These Debye temperatures are in fair agreement with ΘOoc1 values calculated from low temperature elastic constant measurements. Electron effective masses (calculated from γ) are 1.37 ± 0.01 for Rb and 1.80 ± 0.04 for Cs. Thermal effective masses for all the alkali metals are compared with recent theoretical results. Sample purities were checked by an independent spectrographic analysis and by making a thermal analysis in the melting region on the actual specific heat samples. These thermal analysis results led to a review of earlier work on the melting of these metals and the following revised values of melting point and latent heat of melting were obtained: Rb: 312.47 ± 0.02 °K, 524.3 ± 1.0 cal/g atom; Cs: 301.67 ± 0.13 °K, 501.0 ± 1.0 cal/g atom.

Specific heat below 3 °K of a gold–zinc and a gold–indium alloy

1969 ◽  
Vol 47 (10) ◽  
pp. 1077-1081 ◽  
Author(s):  
Douglas L. Martin
Keyword(s):  
Specific Heat ◽  
Face Centered Cubic ◽  
Electronic Specific Heat ◽  
Confidence Limits ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Atomic Silver ◽  
Face Centered ◽  
Specific Heat Coefficient ◽  
Limiting Value

Face-centered-cubic alloys of gold with 10 atomic % zinc (divalent) and 10 atomic % indium (trivalent), respectively, were measured in the range 0.4 to 3.0 °K. The coefficients of the nuclear specific-heat term were 1.80 ± 0.07 μcal °K/g atom for AuZn and 1.29 ± 0.06 μcal °K/g atom for AuIn (95% confidence limits). For a gold–10 atomic % silver (monovalent) alloy (Martin 1968) the nuclear term was 0.44 μcal °K/g atom. These results show that electric field gradients in alloys are not simply proportional to the valence difference of the components, a conclusion which may be drawn from NMR results. For the AuZn alloy the electronic specific-heat coefficient (γ) is 153.4 ± 0.7 μcal/°K2 g atom and the limiting value of the Debye temperature (θ0c) is 177.0 ± 0.5 °K. For the AuIn alloy γ is 185.9 ± 0.7 μcal/°K2 g atom and θ0c is 159.1 ± 0.3 °K.

Hole density dependence of the low temperature electronic specific heat coefficient of La2-xSrxCaCu2O6 with weakly localized electrons

1993 ◽  
Vol 209 (4) ◽  
pp. 553-558 ◽  
Author(s):  
Takashi Nishikawa ◽  
Shin-ichi Shamoto ◽  
Masafumi Sera ◽  
Masatoshi Sato ◽  
Shigeki Ohsugi ◽  
...  
Keyword(s):  
Low Temperature ◽  
Specific Heat ◽  
Density Dependence ◽  
Hole Density ◽  
Electronic Specific Heat ◽  
Specific Heat Coefficient ◽  
Localized Electrons

Specific heat of InBi below 30 K

1981 ◽  
Vol 59 (4) ◽  
pp. 567-575 ◽  
Author(s):  
Douglas L. Martin
Keyword(s):  
Specific Heat ◽  
Debye Temperature ◽  
Thermal Contact ◽  
Adiabatic Calorimeter ◽  
Electronic Specific Heat ◽  
Good Thermal Contact ◽  
Debye Temperatures ◽  
Isoperibol Calorimeter ◽  
Specific Heat Coefficient

There was difficulty in establishing good thermal contact with InBi, a very anisotropic material. This is not believed to have affected results from the 2.5–30 K adiabatic calorimeter. However, results from the 0.35–3 K isoperibol calorimeter are a few percent high in the overlap range owing to uncompensated heat loss during heating periods. Consequently there is some uncertainty in the determination of the electronic specific heat but little uncertainty in Debye temperatures above 1 K (because the lattice specific heat is so large). Despite the great anisotropy, mass-layering, and easy cleaving in one direction, the variation of Debye temperature with temperature is quite normal, there being no evidence of two-dimensional behavior (cf. graphite). The preferred analysis gives the electronic specific heat coefficient as 97.1 ± 0.8 μcal K−2 g-at.−1 (406 ± 3 μJ K−2 g-at.−1) and the low temperature limiting value of Debye temperature as 139.8 ± 0.4 K.

Low temperature specific heats of zinc alloyed with silver

1975 ◽  
Vol 343 (1634) ◽  
pp. 363-374 ◽  
Keyword(s):  
Low Temperature ◽  
Fermi Level ◽  
Specific Heat ◽  
Debye Temperature ◽  
Density Of States ◽  
Electronic Specific Heat ◽  
Pure Zinc ◽  
Specific Heats ◽  
Complete Breakdown ◽  
Specific Heat Coefficient

Measurements of the electronic specific heat coefficient and of the limiting Debye temperature are reported for pure zinc and for two n-phase alloys containing 2 at. % and 4 at. % silver in zinc, respectively. After a correction for electron-phonon enhancement the electronic specific heat coefficient for pure zinc differs by only a small percentage from the calculated value reported in the literature on the basis of a band calculation. The results for the alloys show a decreasing trend of the density of states at the Fermi level when silver is added to zinc. This is contrary to a prediction based on a rigid band approach. Hence, the results indicate a complete breakdown of the rigid band condition on alloying. The reasons for this are most likely associated with the influence of the d band electrons or with charge distribution effects between solute and solvent atoms.

Experimental evidence for the Fermi surface overlap effect in ε-phase Ag—Zn alloys, obtained from low temperature specific heats

1975 ◽  
Vol 343 (1634) ◽  
pp. 375-387 ◽  
Keyword(s):  
Theoretical Model ◽  
Low Temperature ◽  
Specific Heat ◽  
Brillouin Zone ◽  
Band Gaps ◽  
Electronic Specific Heat ◽  
Specific Heats ◽  
Ε Phase ◽  
Specific Heat Coefficient ◽  
Zn Alloys

Measurements of the electronic specific heat coefficient and of the limiting Debye temperature are reported for ten Ag-Zn alloys in the range of the h.e.p. ε-phase. After a correction for the electron-phonon enhancement, the trend of the electronic specific heat coefficient is consistent with a nearly rigid band behaviour, showing a general decrease of the density of states at the Fermi level when the corners of the Brillouin zone are filled. A slight deviation from this trend occurs at electron concentration values exceeding approximately 1.85 5 , in agreement with other measured properties and confirming a theoretical model involving overlaps of electrons across the {00.2} planes of the Brillouin zone. The estimated band gaps are of the order of 2 eV. I t appears that whereas in the dilute rj-phase alloys of zinc with silver the rigid band condition is not valid the opposite is true in the concentrated ε-phase alloys.

Development of the room temperature protocol based on room temperature ionic liquids and surfactant ionic liquids for the synthesis of derivatives of 2-amino-thiazoles and thermo-physical analysis of the synthesized derivatives using TGA-DSC.

2020 ◽  
Vol 10 ◽  
Author(s):  
Chandrakant Sarode ◽  
Sachin Yeole ◽  
Ganesh Chaudhari ◽  
Govinda Waghulde ◽  
Gaurav Gupta
Keyword(s):  
Thermal Analysis ◽  
Heat Capacity ◽  
Ionic Liquids ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Room Temperature ◽  
Heat Capacity Data ◽  
General Strategy ◽  
Capacity Data ◽  
Derivatives Of

Aims: To develop an efficient protocol, which involves an elegant exploration of the catalytic potential of both the room temperature and surfactant ionic liquids towards the synthesis of biologically important derivatives of 2-aminothiazole. Objective: Specific heat capacity data as a function of temperature for the synthesized 2- aminothiazole derivatives has been advanced by exploring their thermal profiles. Method: The thermal gravimetry analysis and differential scanning calorimetry techniques are used systematically. Results: The present strategy could prove to be a useful general strategy for researchers working in the field of surfactants and surfactant based ionic liquids towards their exploration in organic synthesis. In addition to that, effect of electronic parameters on the melting temperature of the corresponding 2-aminothiazole has been demonstrated with the help of thermal analysis. Specific heat capacity data as a function of temperature for the synthesized 2-aminothiazole derivatives has also been reported. Conclusion: Melting behavior of the synthesized 2-aminothiazole derivatives is to be described on the basis of electronic effects with the help of thermal analysis. Additionally, the specific heat capacity data can be helpful to the chemists, those are engaged in chemical modelling as well as docking studies. Furthermore, the data also helps to determine valuable thermodynamic parameters such as entropy and enthalpy.

scholarly journals Structure, Morphology, Heat Capacity, and Electrical Transport Properties of Ti3(Al,Si)C2 Materials

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3222
Author(s):  
Kamil Goc ◽  
Janusz Przewoźnik ◽  
Katarzyna Witulska ◽  
Leszek Chlubny ◽  
Waldemar Tokarz ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Heat Capacity ◽  
Specific Heat ◽  
Electrical Transport ◽  
Residual Resistivity ◽  
Max Phase ◽  
Electrical Transport Properties ◽  
Debye Temperatures ◽  
Si Content ◽  
Hot Pressing Sintering

A study of Ti3Al1−xSixC2 (x = 0 to x = 1) MAX-phase alloys is reported. The materials were obtained from mixtures of Ti3AlC2 and Ti3SiC2 powders with hot pressing sintering technique. They were characterised with X-ray diffraction, heat capacity, electrical resistivity, and magnetoresistance measurements. The results show a good quality crystal structure and metallic properties with high residual resistivity. The resistivity weakly varies with Si doping and shows a small, positive magnetoresistance effect. The magnetoresistance exhibits a quadratic dependence on the magnetic field, which indicates a dominant contribution from open electronic orbits. The Debye temperatures and Sommerfeld coefficient values derived from specific heat data show slight variations with Si content, with decreasing tendency for the former and an increase for the latter. Experimental results were supported by band structure calculations whose results are consistent with the experiment concerning specific heat, resistivity, and magnetoresistance measurements. In particular, they reveal that of the s-electrons at the Fermi level, those of Al and Si have prevailing density of states and, thus predominantly contribute to the metallic conductivity. This also shows that the high residual resistivity of the materials studied is an intrinsic effect, not due to defects of the crystal structure.

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