“… 11 log−log representation of compensation temperature ( T C ) versus equimolar EGC temperature or mean temperature ( T m ) for given system or family. Empty circles are isolated systems: 1, Ar + Kr; 2, Kr + Xe; 3, d -carvoxime + l -carvoxime; 4, 1,2,4,5-tetrachlorobenzene + 1,2,4,5-tetrabromobenzene; 5, Ni + Au; 6, Pd + Au; 7, SrO + BaO; 8, MgO + CaO; 9, CBr 4 + C 2 Cl 6 ; 10, CCl 4 + C(CH 3 ) 4 . Solid symbols: I, p -dihalobenzene family; II, common-ion alkali halide family; III, n -alkane family; , IV, the class of neopentane derivatives …”
Section: Discussionmentioning
confidence: 99%
“…This procedure can be automatically carried out by means of the WINIFIT 2.0 software 24 (based upon the MS-DOS LIQFIT and PROPHASE programs 25,26 ), which also allows us to calculate the different compositions at each temperature at which transitions take place, that is to say, the complete phase diagram. The program was successfully tested in other thermodynamic analyses of two-component systems. − …”
Section: Thermodynamic Analysismentioning
confidence: 99%
“…The output is the excess Gibbs energy change between the liquid and the SC−OD state at the mean temperature ( T m = T EGC ( X = 0.5)) of the [SC + L] loop given by a two-parameter form of a Redlich−Kister polynomial Equation 7 is strictly valid at T m , and it seems to be temperature-independent. A simple way to take into account the temperature dependence is to adopt a quasi-subregular solution model that proved to be useful in the past for the melting of other OD mixed states. ,, In such a model, the excess Gibbs energy change can be written as The constant Δ A 1 expresses the change in the magnitude of the excess function. Δ A 2 is a measure of its asymmetry, and T C , the named compensation temperature or characteristic temperature, is defined as the ratio between the excess enthalpy change and the excess entropy change; therefore, it is the temperature at which the excess Gibbs energy change becomes zero.…”
The two-component system cycloheptanol (C7) + cyclooctanol (C8) has been studied by means of thermal
analysis, X-ray powder diffraction, and dielectric spectroscopy. In a first step, the polymorphism of pure C7
and C8 has been revised, and new unpublished crystallographic data of the stable phases have been reported.
Evidence for the isomorphism relationship between the simple cubic (SC) phases of both of the pure components
has been seen through the continuous evolution of the lattice parameters, the continuous evolution of the
dielectric strength, and the existence of a two-phase equilibrium [SC + L]. Despite the solid polymorphism
of the pure components, the SC state has been observed to be the sole mixed solid state between 170 K and
[SC + L] equilibrium. To perform a complete thermodynamic analysis, measurements of the excess enthalpy
in the liquid state were undertaken. These measurements together with the experimental melting-phase diagram
allow us to determine the excess thermodynamic properties of the mixed SC state via a compensation law.
Dielectric data have been used to interpret the excess properties, and the existence of short-range orientatonal
order for the mixed SC state has been inferred. In addition, this OD mixed state has been classified as
extraordinary in light of the log T
C−log T
m plot.
“… 11 log−log representation of compensation temperature ( T C ) versus equimolar EGC temperature or mean temperature ( T m ) for given system or family. Empty circles are isolated systems: 1, Ar + Kr; 2, Kr + Xe; 3, d -carvoxime + l -carvoxime; 4, 1,2,4,5-tetrachlorobenzene + 1,2,4,5-tetrabromobenzene; 5, Ni + Au; 6, Pd + Au; 7, SrO + BaO; 8, MgO + CaO; 9, CBr 4 + C 2 Cl 6 ; 10, CCl 4 + C(CH 3 ) 4 . Solid symbols: I, p -dihalobenzene family; II, common-ion alkali halide family; III, n -alkane family; , IV, the class of neopentane derivatives …”
Section: Discussionmentioning
confidence: 99%
“…This procedure can be automatically carried out by means of the WINIFIT 2.0 software 24 (based upon the MS-DOS LIQFIT and PROPHASE programs 25,26 ), which also allows us to calculate the different compositions at each temperature at which transitions take place, that is to say, the complete phase diagram. The program was successfully tested in other thermodynamic analyses of two-component systems. − …”
Section: Thermodynamic Analysismentioning
confidence: 99%
“…The output is the excess Gibbs energy change between the liquid and the SC−OD state at the mean temperature ( T m = T EGC ( X = 0.5)) of the [SC + L] loop given by a two-parameter form of a Redlich−Kister polynomial Equation 7 is strictly valid at T m , and it seems to be temperature-independent. A simple way to take into account the temperature dependence is to adopt a quasi-subregular solution model that proved to be useful in the past for the melting of other OD mixed states. ,, In such a model, the excess Gibbs energy change can be written as The constant Δ A 1 expresses the change in the magnitude of the excess function. Δ A 2 is a measure of its asymmetry, and T C , the named compensation temperature or characteristic temperature, is defined as the ratio between the excess enthalpy change and the excess entropy change; therefore, it is the temperature at which the excess Gibbs energy change becomes zero.…”
The two-component system cycloheptanol (C7) + cyclooctanol (C8) has been studied by means of thermal
analysis, X-ray powder diffraction, and dielectric spectroscopy. In a first step, the polymorphism of pure C7
and C8 has been revised, and new unpublished crystallographic data of the stable phases have been reported.
Evidence for the isomorphism relationship between the simple cubic (SC) phases of both of the pure components
has been seen through the continuous evolution of the lattice parameters, the continuous evolution of the
dielectric strength, and the existence of a two-phase equilibrium [SC + L]. Despite the solid polymorphism
of the pure components, the SC state has been observed to be the sole mixed solid state between 170 K and
[SC + L] equilibrium. To perform a complete thermodynamic analysis, measurements of the excess enthalpy
in the liquid state were undertaken. These measurements together with the experimental melting-phase diagram
allow us to determine the excess thermodynamic properties of the mixed SC state via a compensation law.
Dielectric data have been used to interpret the excess properties, and the existence of short-range orientatonal
order for the mixed SC state has been inferred. In addition, this OD mixed state has been classified as
extraordinary in light of the log T
C−log T
m plot.
“…The methylchloromethane compounds (CH 3 ) 4Àn CCl n when n varies from 0 to 4 form a group of molecular substances composed of nearly spherical or pseudoglobular molecules which exhibit a mesophase at temperatures below the liquid state where the molecules have rotational freedom and are translationally ordered in a rather symmetrical lattice. [1][2][3][4][5][6][7][8][9][10][11][12][13] Such mesostate is commonly referred as plastic crystalline state and the substances are known as plastic crystals or orientationally disordered crystals (ODIC). 14 In addition, the substances with more than one chlorine atom (i.e., n ¼ 2, 3 and 4) are particularly fascinating substances which display two orientationally disordered (OD) phases with two melting points about 5 K apart.…”
Section: Introductionmentioning
confidence: 99%
“…2,5 Several twocomponent systems relating to such compounds have been carefully studied. 5,[7][8][9]11,12,[19][20][21] Particularly, the analysis of the two-component systems (CH 3 ) 2 CCl 2 + CCl 4 7 and (CH 3 )CCl 3 + CCl 4 5 has demonstrated a isomorphism relationship between the stable OD rhombohedral phases. Thus, a continuous formation of mixed crystals in the 2,2-dichloropropane ((CH 3 ) 2 -CCl 2 ) + methylchloroform ((CH 3 )CCl 3 ) two-component system studied in this work, is expected.…”
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