Zero Kelvin Research Articles

The Difference in Entropy Between a Stable and Metastable Phase as the Temperature Approaches Zero Kelvin

Summary The free energy of two different phases not in equilibrium at the limit of zero Kelvin must be different. This difference in free energy can be related to the enthalpy and entropy, resulting in a general relation between the transition entropy and enthalpy at the limit of zero Kelvin.

La1-XSrXFeO3-δ の絶対零度付近から高温までの熱容量測定

Isobaric heat capacities, Cp, of LaXSr1-XFeO3-δ solid solutions from near absolute zero Kelvin (2 K) to high temperature (1340 K) were measured by a relaxation method and differential scanning calorimetry. Also, their Debye temperatures, ΘD, were determined from the measured Cp values below 10 K and isochoric heat capacities, CV, were calculated by inserting the ΘD values into Debye functions, followed by calculating the isochoric entropies of vibration, Δ0TSV. From the measured Cp values, it was found that oxygen vacancy (Vo) formed by a self-compensating reaction by doping of Sr′La decreased the onset temperatures of the magnetic and structure phase transitions, broadening the temperature ranges of such phase transitions. The entropies of vibration of oxygen vacancy, ΔfSTvib.V(Vo), estimated by differentiation of Δ0TSV with the Vo content at 298 K and 800 K were 58.65 J•K-1•mol-1 and 64.59 J•K-1•mol-1, respectively. Such a large ΔfSTvib.V(Vo) appears to be one of important reason for foming Vo.

Determination of Standard Gibbs Energy of Formation of Al<SUB>2</SUB>Nd by Solution Calorimetry and Heat Capacity Measurement from Near Absolute Zero Kelvin

The thermodynamic properties of Al 2 Nd were investigated by calorimetry. The standard entropy of formation of Al 2 Nd at 298 K, Δ f S° 298 (Al 2 Nd), was determined from measuring the heat capacities, Cp, from near absolute zero (2K) to 300 K by the relaxation method. The standard enthalpy of formation of Al 2 Nd at 298 K, Δ f H° 298 (Al 2 Nd), was determined by solution calorimetry in hydrochloric acid solution. The standard Gibbs energy of formation of Al 2 Nd at 298 K, Δ f G° 298 (Al 2 Nd), was determined from these data. The results were obtained as follows: Δ f S° 298 (Al 2 Nd)/J·K -1 ·mol -1 = -10.7±1.2, Δ f H° 298 (Al 2 Nd)/kJ·mol -1 = -105.03 ± 27, and Δ f G° 298 (Al2Nd)/kJ·mol -1 = -101.85 ±27.

Standard Gibbs Energy of Formation of Zn<SUB>8</SUB>La Determined by Solution Calorimetry and Measurement of Heat Capacity from Near Absolute Zero Kelvin

The thermodynamic properties of Zn 8 La were investigated by calorimetry. The standard entropy of formation at 298 K, Δ f S 298 , was determined from measuring the heat capacities, Cp, from near absolute zero (2 K) to 300 K by the relaxation method. The standard enthalpy of formation at 298 K, Δ f H 298 , was determined by solution calorimetry in hydrochloric acid solution. The standard Gibbs energy of formation at 298 K, Δ f G 298 , was determined from these data. The results obtained were as follows: Δ f H 298 (Zn8La)/kJ·mol -1 =-297.18 ±18; Δ f S 298 (Zn 8 La)/J·mol -1 ·K -1 = -25.02±3.60; Δ f G 298 (Zn 8 La)/kJ·mol -1 =-289.71 ± 18. The coefficient, γ, of the electronic term contributing to the heat capacity of Zn 8 La was small, indicating that decrease of the density of states for 4f component of the lanthanum atom in the vicinity of E F .

Thermodynamics of self-assembly of ions in the ITO solid solution

Entropies of mixing, Δ mix S 298, at 298 K of Sn-doped In-based transparent Conducting Oxides (ITOs) were determined by measuring heat capacities from near absolute zero Kelvin (2 K). The Δ mix S 298 values were found to be below zero, indicating that short range orderings of Sn In and O i ″ are caused by a thermodynamic self-assembly to compensate charges. Such a self-assembly makes Sn In and O i ″ levels in the band gap degenerate. The degeneracy prevents absorption of visible light, remaining wide band gap over than 3 eV. As a result, ITOs have good transparency while high conductivity.

Standard gibbs energy of formation of Mg48Zn52 determined by solution calorimetry and measurement of heat capacity from near absolute zero kelvin

The thermodynamic properties of Mg48Zn52 were investigated by calorimetry. The standard entropy of formation at 298 K, Δf S 298 o , was determined from measuring the heat capacity, C p , from near absolute zero (2 K) to 300 K by the relaxation method. The standard enthalpy of formation at 298 K, Δf H 298 o , was determined by solution calorimetry in hydrochloric acid solution. The standard Gibbs energy of formation at 298 K, Δf G 298 o , was determined from these data. The obtained results were as follows: Δf H 298 o (Mg48Zn52)=(−1214±(300) kJ · mol−1;ΔfS 298 o (Mg48Zn52)=(−123±0.36) J · K−1 · mol−1; and Δf G 298 o (Mg48Zn52)=(−1177±(300) kJ · mol−1. The electronic contribution to the heat capacity of Mg48Zn52 was found to be approximately equal to pure magnesium, indicating that the density of states in the vicinity of the Fermi level follows the free electron parabolic law.

Response to Comment on “High-Level ab Initio and Density Functional Study of the CH + NO Reaction Product Branching”

Response to Comment on “High-Level ab Initio and Density Functional Study of the CH + NO Reaction Product Branching”

Planck−Benzinger Thermal Work Function: Thermodynamic Approach to Site-Specific S-Protein and S-Peptides Interactions in the Ribonuclease S‘ System

The Planck−Benzinger thermal work function ΔW(T) represents the strictly thermal components of any intra- or intermolecular bonding term in a system, that is, energy other than the inherent difference of the 0 K portion of the interaction energy. The latter, the temperature-invariant enthalpy, is the only energy term at absolute zero Kelvin. The magnitude of ΔH(T0) or ΔH°(T0), the temperature-invariant enthalpy, is determined by the type of macromolecular interaction taking place under experimental conditions, and thus, this thermodynamic function should be particularly applicable to studies on the ribonuclease S-protein interaction with S-peptides with various substitutions at methionine-13. Values for ΔH(T0) for the S-protein−S-peptides interaction with such substitution at Met-13 were determined to be 25.67 ± 0.63 (Met-13 → Ala), 85.69 ± 0.35 (Met-13 → Phe), and 22.32 ± 0.19 kcal mol-1 (Met-13 → α-amino-N-butyric acid). A possible model for the fragment complementation reaction of S-peptide with S-protein if phenylalanine were to be substituted for Met-13 is proposed. The model incorporates feasible strong, site-specific Phe−Phe interaction, giving rise to the large temperature-invariant enthalpy. This thermodynamic approach should be an essential component of all future studies involving the site-directed, mutagenic approach to the examination of structure−function problems in proteins.

Deposition and Surface Dynamic of Metals Studied by the Embedded-Atom Molecular Dynamics Method

Abstract The embedded atom method (EAM) was used to simulate the dynamics of deposition of supported metal clusters on fcc transition metals and the dynamic behavior of surfaces. The formation of metal clusters was observed before deposition and the geometries, stabilities and dynamics of a series of metal clusters were discussed as obtained by EAM and compared with first-principle calculations. The calculations indicate that the structure of a cluster in the vapor phase is governed by its zero kelvin stability. We find that if the cluster forms in the vapor phase, it is difficult to get epitaxial growth since the metal cohesive energy is large and the chester can not be broken by thermal motions. The effect of impurities on the deposition is also discussed. The anharmonicity, roughening and reconstruction of surface were also investigated. Three-body interactions were found to he important to understand these phenomena

Ir-Mn-Sn系における新L2<SUB>1</SUB>型金属間化合物と磁性

Crystal structures and magnetic properities of Ir-Mn-Sn alloys have been investigated by means of X-ray diffraction and magnetic analysis. It has been found that a new L21-type intermetallic compound (Heusler alloy) of Ir1.8Mn1.2Sn exists in the Ir-Mn-Sn system and forms a solid solution in a wide composition range, where Ir1.8Mn1.2Sn to Ir1.6Mn1.4Sn have lattice parameters of 0.6204 to 0.6189 nm, magnetic moments of 3.2 to 2.6 μB/Mn and Curie temperatures of 342 to 265 K. The typical Ir1.8Mn1.2Sn compound has a lattice parameter of 0.6204 nm, a magnetic moment of 3.38 μB/Mn at absolute zero Kelvin and a Curie temperature of 342 K. The magnetization and Curie temperature of their alloys decrease with decreasing lattice parameters, which depend on Mn-Mn interatomic distance remakably.The solid solution of the C1-type has been obtained near the composition of equi-atomic ratio, but their alloys have not characteristic values of the ferromagnetic C1-type compounds.

Experimental determination of dynamic Young's modulus and mechanical damping, and theoretical prediction of dislocation density for depleted uranium-0.75 wt% titanium using the PUCOT

Dynamic Young's modulus (E) and mechanical damping (Q−1) measurements were made for three microstructures (γ, α + δ, and α′) of a depleted uranium-0.75 wt% titanium alloy. The temperature range covered was 298 to 1123 K. The apparatus was the piezoelectric ultrasonic composite oscillator technique (PUCOT) operated at 80 kHz. The ranges of values for E and Q−1 were 193 to 99 GPa and 3×10−3 to 8×10−2, respectively. Correlations for E of each heat treatment as functions of temperature are presented. In addition, the mechanical damping against strain amplitude plots generated from PUCOT data were analysed using the Granato-Luecke zero Kelvin and high-temperature theories of dislocation damping. Computed dislocation densities ranged up to 1016m−2.

'Short' weak links for 115 GHz mixers

It has been proved that the current phase relation of a 'short' weak link in the 'dirty' limit at absolute zero Kelvin is expressed in a Fourier series as I = \frac{\pi\Delta}{2eR} \Sigma\min{n=1}\max{\infin} \frac{(-1)^{n+1}}{n^{2}-\frac{1}{4}} \sin n\psi . We have realized 'short' weak links with a three-dimensionnal geometrical structure. Fabrication techniques of the 'short' weak links have been disclosed. We have made 115 GHz Josephson-effect mixers of the 'short' weak links.

Progress report on superconductivity

High-speed ground transport, ship propulsion, electrical power production, high sensitivity measurements, surgery, fusion reactors, mineral enrichment and pollution control are some of the applications where the use of commercial superconducting materials is now under research. It is now clear that the economical and technical feasibility of some of the developments listed above will only be made possible by the use of superconducting materials which will help to overcome the intrinsic limitations of normally employed techniques. This paper gives data on commercial materials presently available and those which are at the development stage, as well as major applications currently under research. Emphasis is made on the technological problems related to the reliable use of near zero Kelvin temperatures. Some data are also given on large scale undertakings in various nations, with indications of the more mature applications.