functions of zinnwaldite in the same temperature range and its calorimetric entropy at 298.15 K. Furthermore, heat capacity and thermodynamicfunctions at 298.15 K for zinnwaldite of ideal composition KLiFeAl 2 Si 3 O 10 F 2 have been estimated
of thermodynamic property for this substance is necessary. In this study, the low-temperature heat capacities of this compound over the temperature range from 78 to 350 K were measured by an automated adiabatic calorimeter. The thermodynamicfunctions
the study in detail. In this article, we report the phase diagram study, thermal study of the pure compounds and the eutectics such as heat of fusion, Jackson’s roughness parameter, excess thermodynamicfunctions, and microstructural study. However
, calculation of standard ( p ° = 0.1 MPa) thermodynamicfunctions: , H °( T ) − H °(0), S °( T ), and G °( T ) − H °(0) of crystalline Ph 4 SbONCPhMe from T → 0 K to 350 K using the experimental data, determination of combustion energy of the compound
are important basic thermodynamicfunction of substances. Based on the polynomials of molar heat capacity and the thermodynamic relationships, the [ H T − H 298.15 ] and [ S T − S 298.15 ] of DPFEB are calculated over the experimental temperature
–380 K. The thermodynamic properties including molar enthalpy and entropy of phase transition were determined based on the heat capacity measurement. Further more, the thermodynamicfunctions such as [
] and [
] were calculated from the heat capacity
– 22 ] as examples).
The aim of this study was to study the heat capacity of this crystal in a wide temperature range by adiabatic calorimetry, to calculate the thermodynamicfunctions and to compare the results with those previously obtained
The equations describing the excess solution thermodynamicfunctions can be presented as [ 24 , 27 , 28 ]:
(21) (22) (23) (24) (25) (26) (27) (28)
where ϕ and γ are osmotic and activity coefficients, respectively; and are the partial molar
]. In this study results of experimental studying of temperature dependence of a heat capacity of crystal compound Ba 0.5 Zr 2 (PO 4 ) 3 over the temperature range 6–612 K are presented, the standard thermodynamicfunctions C p o ( T ), H °( T ) − H
The heat capacity of solid NdBr3 was measured by Differential Scanning Calorimetry in the temperature range from 300 K up to the melting temperature. The
heat capacity of liquid NdBr3 was also determined. These results were least-squares fitted to a temperature polynome. The melting enthalpy of NdBr3 was measured separately. DSC was used also to study phase equilibrium in the NdBr3-LiBr system. The results obtained provided a basis for constructing the phase diagram of the system under investigation.
It represents a typical example of simple eutectic system. The eutectic composition, x(NdBr3)=0.278, was obtained from the Tamman construction. This eutectic mixture melts at 678 K. The electrical conductivity of NdBr3-LiBr liquid mixtures and of pure components was measured down to temperatures below solidification. Reflectance spectra of
the pure components and their solid mixtures (after homogenisation in the liquid state) with different composition were recorded
in order to confirm the reliability of the constructed phase diagram.