Heat capacity, enthalpy and entropy of Sr14Co11O33 and Sr6Co5O15

2014 ◽  
Vol 575 ◽  
pp. 167-172 ◽  
Author(s):  
Ondřej Jankovský ◽  
David Sedmidubský ◽  
Zdeněk Sofer ◽  
Jindřich Leitner ◽  
Květoslav Růžička ◽  
...  
Author(s):  
I. N. Ganiev ◽  
S. E. Otajonov ◽  
N. F. Ibrohimov ◽  
M. Mahmudov

In the heat «cooling» investigated the temperature dependence of the specific heat capacity and thermodynamic functions doped strontium alloy AK1М2 in the range 298,15—900 K. Mathematical models are obtained that describe the change in these properties of alloys in the temperature range 298.15—900 K, as well as on the concentration of the doping component. It was found that with increasing temperature, specific heat capacity, enthalpy and entropy alloys increase, and the concentration up to 0.5 wt.% of the alloying element decreases. Gibbs energy values have an inverse relationship, i.e., temperature — decreases the content of alloying component — is up to 0.5 wt.% growing.


1981 ◽  
Vol 10 (11) ◽  
pp. 785-801 ◽  
Author(s):  
N. Rajagopalan ◽  
M. Vadnere ◽  
S. Lindenbaum

2014 ◽  
Vol 525 ◽  
pp. 141-145
Author(s):  
Qing Fen Meng ◽  
Xiao San Xia

A new complex [Na (H2O)2]6[MoCo6O12(H2O)12]·4.3H2O(s) was synthesized and determined by X-ray crystallography. Low-temperature heat capacities of the compound was measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 380 K. An obvious dehydration process was found in the heat capacity curve of the title compound. The temperature, enthalpy and entropy of the dehydration process were determined to be (370.266±0.292) K, (187.455±0.354) kJ·mol-1, (50.627±0.078) J·K-1·mol-1 by three series of repeated heat capacity measurements in the region of thermal decomposition.


2005 ◽  
Vol 60 (1-2) ◽  
pp. 23-28
Author(s):  
Akira Matsumoto

The thermodynamic quantities of Lennard-Jones gases, evaluated till the fourth virial coefficient, are investigated for an isobaric process. A partition function in the T-P grand canonical ensemble Y(T,P,N) may be defined by the Laplace transform of the partition function Z(T,V,N) in the canonical ensemble. The Gibbs free energy is related with Y(T,P,N) by the Legendre transformation G(T,P,N) = −kT logY(T,P,N). The volume, enthalpy, entropy, and heat capacity are analytically expressed as functions of the intensive variables temperature and pressure. Some critical thermodynamic quantities for Xe are calculated and drawn. At the critical point the heat capacity diverges to infinity, while the Gibbs free energy, volume, enthalpy, and entropy are continuous. This suggests that a second-order phase transition may occur at the critical point.


1997 ◽  
Vol 62 (5) ◽  
pp. 679-695
Author(s):  
Josef P. Novák ◽  
Anatol Malijevský ◽  
Jaroslav Dědek ◽  
Jiří Oldřich

It was proved that the enthalpy of saturated vapour as a function of temperature has a maximum for all substances. The dependence of the entropy of saturated vapour on temperature can be monotonous, has a minimum and a maximum, or has only a maximum. The thermodynamic relations were derived for the existence of the extremes which enable their computation from the knowledge of dependence of the ideal-gas heat capacity on temperature and an equation of state. A method based on the theorem of corresponding states was proposed for estimating the extremes, and its results were compared with literature data. The agreement between the literature and estimated temperatures corresponding to the extremes is very good. The procedure proposed can serve for giving precision to the H-p and T-S diagrams commonly used in applied thermodynamics.


1962 ◽  
Vol 58 ◽  
pp. 1511 ◽  
Author(s):  
D. M. Evans ◽  
F. E. Hoare ◽  
T. P. Melia

2018 ◽  
Vol 4 (3) ◽  
pp. 119-124
Author(s):  
Izatullo N. Ganiev ◽  
Suhrob E. Otajonov ◽  
Nasim F. Ibrohimov ◽  
M. Mahmudov

The temperature dependence of the specific heat capacity and change in the thermodynamic functions of strontium-alloyed ultrahigh-purity aluminum base AK1M2 alloy have been studied in “cooling” mode over the 298.15–900 K range. Mathematical models describing the evolution of these properties of the alloys in the abovementioned temperature range with change in alloying addition concentration have been obtained. The heat capacity, enthalpy and entropy of the alloys increase with temperature, decrease with an increase in the alloying addition concentration to 0.5 wt.% and grow with a further increase in the alloying addition concentration. The Gibbs energy of the alloys has an inverse dependence: it decreases with an increase in temperature and grows with an increase in the alloying addition concentration to 0.5 wt.%.


Author(s):  
I. N. Ganiev ◽  
S. E. Otajonov ◽  
M. Mahmudov ◽  
M. M. Mahmadizida ◽  
V. D. Abulkhaev

It is known that high purity aluminum with a minimum content of impurities is widely used in electronic technology for the manufacture of conductive paths in integrated circuits. Hence the development of new compositions of alloys based on such a metal is a very urgent task. One of the promising alloys based on such a metal is alloy AK1M2 (Al + 1 % Si + 2 % Cu). This alloy was accepted by us as a model alloy and subjected to modification by alkaline earth metals.Heat capacity is the most important characteristic of substances and by its variation with temperature one can determine the type of phase transformation, the Debye temperature, the energy of formation of vacancies, the coefficient of electronic heat capacity, and other properties. In the present work, the heat capacity of the AK1M2 alloy with alkaline earth metals was determined in the “cooling” mode from the known heat capacity of a reference sample from copper. For which, by processing the curves of the cooling rate of samples from the alloy AK1M2 with alkaline earth metals and the standard, polynomials were obtained which describe their cooling rates. Further, by experimentally found values of the cooling rates of the standard and samples from alloys, knowing their masses, the polynomials of the temperature dependence of the heat capacity of the alloys and the standard were established, which are described by a four-term equation. Using the integrals of the specific heat, the models of temperature dependence of the change in enthalpy, entropy and Gibbs energy were established.The dependences obtained show that with an increase in temperature, the heat capacity, enthalpy, and entropy of alloys increase, and the values of Gibbs energy decrease. At the same time, additives of alkaline earth metals do not significantly reduce the heat capacity, enthalpy and entropy of the original alloy AK1M2 and increase the value of Gibbs energy. During the transition from alloys with calcium with barium, the heat capacity of the alloys decreases, which correlates with the heat capacity of pure alkaline earth metals within the subgroup.


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