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Thermodynamic properties of polycrystalline powders of ruthenium dichalcogenides have been studied using calorimetric isobaric heat capacity measurements in a wide temperature range. The adiabatic and differential scanning calorimetry data for ruthenium disulfide and ruthenium diselenide have been used to determine standard thermodynamic functions (heat capacity, entropy, enthalpy increment, and reduced Gibbs energy) of these compounds in the range 10–965 K. At 298.15 K, the functions of RuS2 are as follows: = 60.82 ± 0.12 J/(K mol), S° = 56.05 ± 0.11 J/(K mol), Н°(298.15 K) − Н°(0) = 9.75 ± 0.02 kJ/mol, and Ф° = 23.34 ± 0.05 J/(K mol). For RuSe2, we have obtained = 69.96 ± 0.14 J/(K mol), S° = 80.62 ± 0.16 J/(K mol), Н°(298.15 K) − Н°(0) = 13.05 ± 0.03 kJ/mol, and Ф° = 36.85 ± 0.08 J/(K mol). The data obtained above 298 K have been used to determine empirical coefficients of the Maier–Kelley and Khodakovsky equations. The absolute entropies obtained in this study for the ruthenium dichalcogenides, in combination with literature data, have made it possible to evaluate the Gibbs energy of formation of RuS2(cr) and RuSe2(cr) at 298.15 K. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of crystalline ruthenium ditelluride (RuTe2) and its thermodynamic properties in the range from 10 to 965 K, evaluated from its isobaric heat capacity Cp determined using calorimetry. At low temperatures, between 6.86 and 335.11 K, the heat capacity of the synthesized material—pure, free of impurities and foreign phases—was determined by adiabatic calorimetry. In the range 315.3–965.3 K, Cp was determined by differential scanning calorimetry. The data obtained above 298 K have been used to determine empirical coefficients of the Maier–Kelley and Khodakovsky equations. In the range 10–965 K, we have evaluated the standard thermodynamic functions: heat capacity, entropy, enthalpy increment, and reduced Gibbs energy. At 298.15 K, we have obtained = 72.43 ± 0.14 J/(K mol), S° = 94.94 ± 0.19 J/(K mol), Н°(298.15 K) − Н°(0) = 14.60 ± 0.03 kJ/mol, and Ф° = 45.97 ± 0.09 J/(K mol). Using the absolute entropy determined by us and data in the literature and handbooks, we have estimated the standard Gibbs energy of formation of RuTe2: ΔfG°(RuTe2, cr, 298.15) = −130.5 ± 2.9 kJ/mol. [ABSTRACT FROM AUTHOR]

The RGaTi2O7 (R = Sm, Ho, Tm, Yb) substituted titanates have been prepared by solid-state reactions, by firing mixtures of the Ga2O3, TiO2, and R2O3 oxides in air at 1273 and 1573 K, and their crystal structure has been determined using X-ray diffraction. The effect of temperature (320–1000 K) on the heat capacity of the synthesized compounds has been studied by differential scanning calorimetry. The experimental Cp(T) data have been used to calculate the principal thermodynamic functions of the titanates. Using the group contribution method, we evaluated the standard enthalpy and Gibbs energy of formation of the RGaTi2O7 (R = Sm, Ho, Tm, Yb) titanates. [ABSTRACT FROM AUTHOR]

The CaSm2Ge3O10 germanate has been prepared by firing stoichiometric mixtures of CaCO3, Sm2O3, and GeO2 in air in the temperature range 1423–1473 K. X-ray powder diffraction characterization with the use of the derivative difference minimization method has shown that CaSm2Ge3O10 has a monoclinic structure (sp. gr. P21/c, 293 К) with unit-cell parameters a = 6.9779(8) Å, b = 6.92859(7) Å, c = 18.8907(2) Å, and β = 108.3280(8)°. The high-temperature heat capacity of calcium samarium germanate samples has been determined in the temperature range 320–1000 K by differential scanning calorimetry and the experimental Cp(T) data have been used to evaluate thermodynamic properties of CaSm2Ge3O10. [ABSTRACT FROM AUTHOR]

We have studied the kinetics of boehmite nanopowder formation during hydrothermal treatment of γ-Al2O3 nanopowder in a 1.5% HCl solution at 200, 170, and 150°C. The results demonstrate that the temperature-dependent reaction rate constant follows the Arrhenius equation. The Ea of the process has been determined to be 84 kJ/mol. The thermodynamics of γ-Al2O3 nanopowder conversion into boehmite during hydrothermal treatment at 150°C has been studied by differential scanning calorimetry. The heat of vaporization of water from a two-phase nanosystem (γ-Al2O3 + forming boehmite) has been determined to be 8, 16, and 22 kJ/mol H2O, which points to an active role of water with a low heat of vaporization in the initial stages of the hydrothermal treatment of the γ-Al2O3 nanopowder. The heat effect of the АlООН → γ-Al2O3 conversion in the nanopowders is lower than the reference value by 7 kJ/mol AlOOH, which is attributable to the small particle size and low structural perfection of the synthesized boehmite (AlOOH). [ABSTRACT FROM AUTHOR]

Phase relations in the Ga-Ge-Sb ternary system were investigated experimentally, using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and differential scanning calorimetry (DSC). Nine ternary samples were prepared by melting of pure elements under an argon atmosphere. The compositions of the prepared alloys were situated along three cross sections with the molar ratios Ga:Ge = 1, Ga:Sb = 1 and Ge:Sb = 1. Phase transition temperatures of the investigated samples were determined using DSC. The microstructure of the samples was analyzed using a scanning electron microscope with EDS and co-existing phases were identified. Binary thermodynamic data from literature, successfully used for phase diagram calculations of binary Ga-Ge, Ga-Sb and Ge-Sb systems, were used for the prediction of phase equilibria in the ternary Ga-Ge-Sb system. The activities of Ga in the liquid phase were calculated using the Redlich-Kister-Muggianu model and compared with experimental data reported in the literature. The liquidus projection, invariant equilibria and three vertical sections of the Ga-Ge-Sb ternary system were calculated and compared with the experimental results and a good agreement was observed. [ABSTRACT FROM AUTHOR]

The Sm2Ge2O7 and Eu2Ge2O7 germanates have been prepared by solid-state reactions via multistep firing of stoichiometric mixtures of Sm2O3 (Eu2O3) and GeO2 in air at temperatures from 1273 to 1473 K. The molar heat capacity of the samarium and europium germanates has been determined by differential scanning calorimetry in the range 350-1000 K and the Cp(T) data have been used to evaluate their thermodynamic properties. [ABSTRACT FROM AUTHOR]

The thermal behavior of (TeO)(MoO) ( n = 0.75, 0.85, 0.90) tellurite glasses has been studied by differential scanning calorimetry in the range from T = 300 to T = 850 K and heat capacity has been measured in the temperature range. The thermodynamic characteristics of the devitrification process and glassy state have been determined. The experimental data obtained have been used to evaluate the standard thermodynamic functions of the system in glassy and supercooled liquid states: heat capacity C °( T), enthalpy H°( T)- H°(320), entropy S°( T)- S°(320), and Gibbs function G°( T)- G°(320) in the temperature range 320-630 K. The composition dependences of the glass transition temperature and thermodynamic functions for the glasses have been obtained. The thermal and thermodynamic properties of the tellurite glasses have been compared to those of previously studied (TeO)(WO) and (TeO)(ZnO) glasses. [ABSTRACT FROM AUTHOR]

Polycrystalline TbBiGeO and DyBiGeO samples have been prepared by solid-state reactions, by firing stoichiometric mixtures of TbO (DyO), BiO, and GeO in air at 1003, 1073, 1123, 1143, 1173, and 1223 K. The molar heat capacity of the bismuth terbium and bismuth dysprosium germanates has been determined by differential scanning calorimetry. The experimental C ( T) data obtained in the range 350-1000 K have been used to evaluate the thermodynamic functions of the synthesized oxide compounds: enthalpy increment, entropy change, and reduced Gibbs energy. [ABSTRACT FROM AUTHOR]

The heat capacity of monoclinic gadolinium orthotantalate has been determined as a function of temperature by adiabatic and differential scanning calorimetry in the temperature range 8-1323 K. Smoothed heat capacity data have been used to calculate the thermodynamic functions of M-GdTaO with allowance for the contribution of its low-temperature magnetic transformations. [ABSTRACT FROM AUTHOR]

YbSnO and LuSnO have been prepared by solid-state reactions, by firing mixtures of YbO or LuO and SnO at 1473 K, and the molar heat capacity of these compounds (pyrochlore structure) has been determined by differential scanning calorimetry. The C ( T) data have been used to evaluate the thermodynamic properties of the stannates: enthalpy increment, entropy change, and reduced Gibbs energy. [ABSTRACT FROM AUTHOR]

The molar heat capacity of PbVO and PbVO in the temperature range 350-1000 K was measured by differential scanning calorimetry. It was determined that the plot C = f( T) for PbVO has an extremum within the range 416-516 K, which is due to a phase transition. A correlation was found between the heat capacity and composition of oxides in the PbO-VO system. The data obtained allowed one to predict the specific heat capacity value for Pb(VO). [ABSTRACT FROM AUTHOR]

Cerium orthovanadate has been prepared by solid-state reaction via multistep firing of a stoichiometric mixture of CeO and VO in the range 873-1273 K. The molar heat capacity of CeVO has been determined by differential scanning calorimetry in the temperature range 350-1000 K. The experimental data have been used to evaluate the thermodynamic properties of cerium orthovanadate: enthalpy increment H°( T)- H°(350 K), entropy change S°( T)- S°(350 K), and reduced Gibbs energy Φ°( T). [ABSTRACT FROM AUTHOR]

The heat capacities of PbVO and Pb(VO) as a function of temperature in the range 350-965 K have been studied by the differential scanning calorimetry method. The C = f( T) curve for PbVO is described by the equation C = (230.76 ± 0.51) + (73.60 ± 0.50)×10 T − (18.38 ± 0.54)×10 T in the entire temperature range. For Pb(VO), there is a well-pronounced extreme point in the C = f( T) curve at T = 371.5 K, which is caused by the existence of a structural phase transition. The thermodynamic properties of the oxide compounds have been calculated. [ABSTRACT FROM AUTHOR]

Phase relations in the BiO-SnO system have been studied using differential thermal analysis, differential scanning calorimetry, X-ray diffraction, and the sessile drop method. The C( T) curve obtained in the range 350-960 K has a number of extrema, which are attributable to structural changes in BiSnO. The experimental C data have been used to evaluate the thermodynamic properties of the oxide compound. [ABSTRACT FROM AUTHOR]

The molar heat capacity of LuVO has been determined by differential scanning calorimetry in the temperature range 404-908 K. The C( T) curve has been shown to have no extrema. The experimental data have been used to evaluate the thermodynamic functions of lutetium orthovanadate in the temperature range studied. [ABSTRACT FROM AUTHOR]

This manuscript focuses on a specialized field within solution thermodynamics that encompasses some of the major macromolecular components comprising all biological systems. Nucleic acids and proteins are large biomolecules that represent quazi-macroscopic systems with highly ordered structures in which each atom occupies a defined space. In view of their unique quaternary structures that resemble aperiodic crystals, one might reasonably surmise that the resultant solution thermodynamics are highly specific. Systematic investigations of these biological macromolecules have necessitated the development of ultrasensitive measurement techniques including differential scanning and isothermal titration calorimetry. These experimental approaches represent the gold standard in terms of microcalorimetric instrumentation designed to characterize complex macromolecular systems. This paper presents an overview of thermodynamic data gleaned from studies employing these calorimetric techniques as part of our comprehensive strategy to characterize the energetic basis of nucleic acid and protein stability. [ABSTRACT FROM AUTHOR]

The heat capacity of PrCuO has been determined by differential scanning calorimetry in the temperature range 364-1064 K. The experimental C( T) data have been used to evaluate the thermodynamic functions of praseodymium cuprate: enthalpy increment H( T)- H(364 K) and entropy change S( T)- S(364 K). [ABSTRACT FROM AUTHOR]

Ternary oxide GdBiGeO was synthesized by a ceramic method. The heat capacity of crystalline gadolinium bismuth germanate as a function of temperature in the range 373-1000 K has been studied by differential scanning calorimetry. It has been demonstrated that the temperature dependence of the heat capacity can be described by the classical Maier-Kelley equation. From the experimental C = f( T) data, the thermodynamic functions (the change in enthalpy and entropy) of ternary oxide GdBiGeO have been calculated. [ABSTRACT FROM AUTHOR]

Phase equilibria in the Mg-rich region of the Mg-Sn-Ag ternary system were determined by quenching experiments, differential scanning calorimetry, electron probe micro-analysis, and X-ray diffraction techniques. No ternary compounds were found in the studied isothermal sections. A critical evaluation of the available experimental data and a thermodynamic optimization of the Mg-Sn-Ag-In quaternary system were carried out using the calculation of phase diagrams method. The modified quasichemical model in the pair approximation was used for the liquid solution, which exhibits a high degree of short-range order. The solid phases were modeled with the compound energy formalism. All available and reliable experimental data were reproduced within experimental error limits. A self-consistent thermodynamic database was constructed for the Mg-Sn-Ag-In quaternary system, which can be used as a guide for Mg-based alloys development. [ABSTRACT FROM AUTHOR]

Magnesium-based bulk metallic glasses (BMG) have potential in applications ranging from biomedical to sports equipment and the Mg-Cu-Y system offers some of the most promising alloys. Phase relations and ternary solubility of the binary and ternary compounds of this system have been experimentally investigated. The Isothermal section of Mg-Cu-Y system at 673 K for the entire composition range has been constructed. Phase relations in the Cu-rich (>66 at.% Cu) region of the Mg-Cu-Y system has been determined for the first time. The homogeneity range of three ternary compounds has been determined. Solidifications behavior of several key alloys have been discussed based on the differential scanning calorimetry (DSC) experiments and thermodynamic calculations. Extensive analysis of the DSC curves has been carried out to relate them to the corresponding phase transformation reactions and temperatures. Some of the most promising metallic glass forming regions have been analyzed using thermodynamic calculations. [ABSTRACT FROM AUTHOR]

The morphology evolution of thermoplastics made by micro-injection molding (μIM) in a uniform miniaturization manner has not been documented yet. In the present study, the crystal morphologies within μIM high-density polyethylene parts were investigated with the aid of rheology measurement, polarizing optical microscopy, scanning electron microscopy, and differential scanning calorimetry. It was discovered that unlike conventional injection molded parts with spherulites predominating, uniformly miniaturized products have highly oriented lamellae starting to appear in the skin layer. For 175-μm-thick μIM parts (M175), interlocking shish–kebab structures exist throughout the thickness. Furthermore, the origins of different crystal morphologies with various part thicknesses were discussed mainly from the viewpoints of rheology and thermodynamics. It was revealed that the flow-induced crystallization is one of the key factors responsible for the unique super structures. More quantitatively, there is a critical shear rate of 3.0 × 10 5 s −1 existing for forming highly oriented molecular structures. Meanwhile, on the basis of the model from the literature, an elongational rate as high as 4.4 × 10 4 s −1 was also identified at the channel center for M175. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the glass transition temperatures of the polystyrene and nanosized hybrid particles through thermodynamic analysis. The study uses gel-permeation chromatography, elemental analysis, and differential scanning calorimetry to determine the glass transition temperature of the materials. Results show that the changes in the glass transition temperature of nanocomposites will depend on the size of hybrid particles.

The liquidus and solidus temperatures and enthalpy of fusion for Ag-Sn alloys are systematically measured within the whole composition range by differential scanning calorimetry (DSC). The measured enthalpy of fusion is related to Sn content by polynomial functions, which exhibit one maximum value at 52 wt%Sn and two minimum values around 21 wt%Sn and 96.5 wt%Sn, respectively. The liquidus slope, the solidification temperature interval, the solute partition coefficient and the entropy of fusion are calculated on the basis of the measured results. The undercoolability of those liquid Ag-Sn alloys solidifying with primary (Ag) solid solution phase is stronger than the other alloys with the preferential nucleation of ζ and ɛ intermetallic compounds. Morphological observations reveal that peritectic reactions can rarely be completed, and the peritectic microstructures are always composed of both primary and peritectic phases. [ABSTRACT FROM AUTHOR]

Grain boundary wetting transitions were previously observed in the Al-Mg system. The melting of as-cast Al-5 wt% Mg and Al-10 wt% Mg alloys was studied by the differential scanning calorimetry. The asymmetric shape of the melting curve permitted the observation of the thermal effect of grain boundary wetting. The difference in the shape of the melting curve for the two studied alloys is explained by the different temperature dependence of the fraction of completely wetted grain boundaries. [ABSTRACT FROM AUTHOR]

The characteristics of carbide transformation in an 8 % Cr roller steel under the conditions of equilibrium, slow heating, and isothermal treatment were investigated using thermodynamic calculation, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The carbides under equilibrium conditions were identified as MC, MC, and MC types. The austenite transformation onset and finish temperatures, Ac and Ac, were 745 and 780 °C, respectively. MC decomposition took place at 820-850 °C and MC at 1060-1130 °C, under slow heating conditions. Quantitative relationships were obtained between the isothermal conditions and average carbide size and aspect ratio, which increased with increasing holding temperature and time. [ABSTRACT FROM AUTHOR]

The molar heat capacity of ScCuO has been determined at temperatures from 350 to 893 K using differential scanning calorimetry. The experimental C( T) data have been used to evaluate the thermodynamic functions of the double oxide. [ABSTRACT FROM AUTHOR]