Superionic Solid Electrolyte Li7La3Zr2O12 Synthesis and Thermodynamics for Application in All-Solid-State Lithium-Ion Batteries

Li7La3Zr2O12Solid-state reaction was used for Li7La3Zr2O12 material synthesis from Li2CO3, La2O3 and ZrO2 powders. Phase investigation by XRD, SEM and EDS methods of Li7La3Zr2O12 were carried out. The molar heat capacity of Li7La3Zr2O12 at constant pressure in the temperature range 298-800 K should be calculated as Cp,m = 518.135+0.599 × T - 8.339 × T−2, where T is absolute temperature, . Thermodynamic characteristics of Li7La3Zr2O12 were determined as next: entropy S0298 = 362.3 J mol-1 K-1, molar enthalpy of dissolution ΔdHLlZO = ˗ 1471.73 ± 29.39 kJ mol−1, the standard enthalpy of formation from elements ΔfH0 = ˗ 9327.65 ± 7.9 kJ mol−1, the standard Gibbs free energy of formation ∆f G0298 = ˗9435.6 kJ mol-1.

Synthesis Method and Thermodynamic Characteristics of Anode Material Li3FeN2 for Application in Lithium-Ion Batteries

Li3FeN2 material was synthesized by the two-step solid-state method from Li3N (adiabatic camera) and FeN2 (tube furnace) powders. Phase investigation of Li3N, FeN2, and Li3FeN2 was carried out. The discharge capacity of Li3FeN2 is 343 mAh g−1, which is about 44.7% of the theoretic capacity. The ternary nitride Li3FeN2 molar heat capacity is calculated using the formula Cp,m = 77.831 + 0.130 × T − 6289 × T−2, (T is absolute temperature, temperature range is 298–900 K, pressure is constant). The thermodynamic characteristics of Li3FeN2 have the following values: entropy S0298 = 116.2 J mol−1 K−1, molar enthalpy of dissolution ΔdHLFN = −206.537 ± 2.8 kJ mol−1, the standard enthalpy of formation ΔfH0 = −291.331 ± 5.7 kJ mol−1, entropy S0298 = 113.2 J mol−1 K−1 (Neumann–Kopp rule) and 116.2 J mol−1 K−1 (W. Herz rule), the standard Gibbs free energy of formation ΔfG0298 = −276.7 kJ mol−1.

Synthesis Method and Thermodynamic Characteristics of Anode Material Li3FeN2 for Application in Lithium-Ion Batteries

Li3FeN2 material was synthesized by two-step solid-state method from Li3N (adiabatic camera) and FeN2 (tube furnace) powders. Phase investigation of Li3N, FeN2 and Li3FeN2 were carried out. Discharge capacity of Li3FeN2 is 343 mAh g-1, that is about 44.7% of theoretic capacity. The molar heat capacity of Li3FeN2 at constant pressure in the temperature range 298-900 K should be calculated as Cp,m = 77,831 + 0,130 × T – 6,289 × T-2, where T is absolute temperature, . Thermodynamic characteristics of Li3FeN2 were determined as next: entropy S0298 = 116.2 J mol-1 K-1, molar enthalpy of dissolution ΔdHLFN = ˗ 206,537 ± 2,8 kJ mol−1, the standard enthalpy of formation ΔfH0 = ˗ 291.331 ± 5.7 kJ mol−1, entropy S0298 = 113.2 J mol-1 K-1 (Neumann-Kopp rule) and 116.2 J mol-1 K-1 (W.Herz rule), the standard Gibbs free energy of formation ∆f G0298 = ˗276,7 kJ mol-1.

Thermodynamical study of (CaGa2S4)x(BaGa2S4)1−x solid solutions

The solid solutions of [Formula: see text] were synthesized by solid-phase reactions from powder components of CaS, BaS, and Ga2S3. The temperature-concentration dependences of the Gibbs free energy of formation of [Formula: see text] solid solutions from ternary compounds and phase diagrams of the CaGa2S4–BaGa2S4 were determined by a calculation method. It was revealed that continuous solid solutions are formed in these systems. The spinodal decomposition of [Formula: see text] solid solutions into two phases is predicted at ordinary temperatures.

Defects

Over time materials change. A material changes towards thermodynamic equilibrium with its environment, or away from equilibrium if it is subjected to external influences such as mechanical deformation, irradiation and chemical attack. In crystalline materials defects are the agents of change. Point defects are agents of diffusion, line defects called dislocations are agents of plastic (permanent) deformation, and planar defects called grain boundaries are agents of recrystallisation and many other processes. In metals diffusion occurs primarily through the motion of vacancies. There is a population of such vacancies in thermodynamic equilibrium. Experimental evidence for their existence and their free energy of formation is presented. The ease of movement of dislocations governs the strength and ductility of crystalline materials. In insulators defects may be electrically charged. Many properties of crystalline materials are governed by defects and their interactions.

THERMODYNAMIC ANALYSIS OF TRICALCIUM SILICATE HYDRATION

Thermodynamic analysis of the hydration processes of tricalcium silicate 3CaO•SiO2 is difficult due to the unreliability of the initial data for hydration products. In addition, there are disagreements about the basicity of the hydration phases (3CaO•SiO2•3H2O or 2CaO•SiO2•2H2O). For the latter, there is no free energy of formation in the reference literature. There are also no data on the water solubility of these calcium hydrosilicates. The proposed values of ∆G0298 for these hydrosilicates, equal to 1064,3 and 639,7, as well as the enthalpies of formation (∆Н0298), equal to 1157,2 and 696,9 kcal/mol, re-spectively. Further thermodynamic calculations were performed using these values. To calculate the composition of the liquid phase, a simplified Born-Haber cycle is used. The values of the calculated heat release of tricalcium silicate with the formation of C3S2H3 and C2SH2, obtained using the pro-posed values of enthalpies, differ little from each other and are close to the experimental data. The calculated solubility of C3S2H3 is 0,7 g/l CaO, and C2SH2 is 0,92 g/l CaO. Since the solubility of C3S2H3 is much lower than of Ca(OH)2 (portlandite), which is formed during hydration of tricalcium silicate in large quantities, C3S2H3 is unstable under these conditions and its basicity increases. It is suggested that C3S2H3 is the main hydration product of CEM III and other cements with a high content of active mineral additives, and C2SH2 is CEM I and CEM II.

Isomers of (L)-Diiodotyrosine - A DFT Treatise

(L)-Diiodotyrosine isomers are considered within the realm of density functional theory at the level of B3LYP/6-311+G(d,p). Their zwitter ionic forms are considered as well. All the structures are electronically stable, have exothermic heat of formation and favorable Gibbs free energy of formation values. Within the limitations of the method the zwitter ionic forms are not different from the corresponding parent structures in the vacuum conditions and no hydrogen bonding seems to exist between the NH2 and COOH groups. Some structural, quantum chemical and spectral data have been collected and discussed.

HELICAL STRUCTURE OF POLYUNSATURATED FATTY ACIDS: GAUSSIAN G4 THERMODYNAMIC FUNCTIONS

Molecular modeling of lipids has been hampered by the size of these complex, biologically important molecules. Yet, understanding the structure and energy (enthalpy) of large molecules is critical to identifying their function in chemical equilibrium and transition state theory. In this work, we use both experimental data and G4 computed results, to show that cis polyunsaturated lipids have helical conformers. We present linear functions for the enthalpy of formation ΔfH°298 and the Gibbs free energy of formation ΔfG°298 as a function of n, where n is the number of carbon atoms in a linear carboxylic acid chain. Taking ΔfH°298 of a saturated acid as a starting point, we add the enthalpy of hydrogenation ΔhydH°298 at appropriate locations on the carbon chain to model polyunsaturated fatty acids. For example, taking eicosanoic acid (C20) as a saturated starting point, we add four enthalpies of cis-dehydrogenation (ΔhydH°298) to obtain arachidonic acid (eicosa-5Z,8Z,11Z,14Z-tetraenoic acid). We compare Gaussian-4 computational results, to show evidence of helical structure. We conclude that fatty acids can have helical conformers facilitating a broad range of biological functions. Keywords: G4 Calculations, Helix, Lipid, Molecular Structure, Thermochemistry

Interaction of 1,1-Diamino-2,2-Dinitroethylene with Aluminum and Gallium Admixture - DFT Treatment

Interaction of 1,1-diamino-2,2-dinitroethylene with nAl+mGa (n,m:1,2) admixture has been investigated within the constraints of density functional theory at the level of UB3LYP/6-311++G(d,p). Various multiplicity states arise for the composites due to the open-shell ground state electronic configurations of Al and Ga atoms. The composites are electronically stable, thermodynamically exothermic and have favorable Gibbs’ free energy of formation values. Various quantum chemical properties have been obtained and discussed. The calculated UV-VIS spectra indicate that some of the composites are infrared absorbing systems beyond 700 nm.

Interaction of Carmustine Tautomers with Adenine - DFT Study

Carmustine is a chemotherapic substance used in treatment of various cancers. In the present study, within the constraints of density functional theory (B3LYP/6-31++G(d,p)), tautomerism of carmustine has been investigated. It may undergo 1,3-type proton tautomerism, however the obtained data for vacuum conditions indicated that the equilibrium concentration of the enol type tautomer should be low. Afterwards, interactions of those tautomers with adenine, a constituent base of DNA and RNA, have been investigated. The composites (1:1) are electronically stable. Their heat of formations are exothermic and the free energy of formation values are favorable. Some of their calculated properties (structural, physicochemical and quantum chemical) are obtained and discussed.