Toward an analytic equation of state for fluorine

There are more than 1000 good experimental measurements of fluid fluorine, which cover the range from the triple point to 300 K for pressures up to 23 MPa. The development of an equation of state to fit these data is described. The form of equation used is that of a reduced Helmholtz energy function which includes an equation to represent the behavior of the ideal gas. The coefficients in the equation are determined by a least-squares method where the terms used are selected statistically from a given bank, thus reducing intercorrelation. Two banks of terms were chosen and various fits made using PT data alone, and multiproperty fits with both banks. The serious consequence of using PT data alone is demonstrated, and the difference in quality between the two banks is described. The problems of inconsistency between the single-phase and the saturated density data are discussed. New equations are given which represent the ideal-gas properties.     

Solution of heat-conduction equation for materials with fading memory and high heat conduction

An analytical solution is obtained of the linearized heat-conduction equation for an isotropic nondeformable body with memory and with high heat conduction.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 31, No. 2, pp. 351–354, August, 1976.     

An equation of state for porous materials under shock loading

Based on the physical interpretation of the linear equation of state (EOS) of dense solids under shock loading, which relates particle and shock speeds asU _s=C _b+gU _p, the EOS for porous solids has been developed and is expressed asU _s*=ΨC _b*+g*U _p whereC _b* andg* are effective bulk sound speed and effective inverse ultimate volume strain respectively. Ψ is a pore collapse function introduced specially to differentiate loading and unloading behaviour.C _b* andg* are derived theoretically whereas Ψ is established empirically as Ψ=f(U _p,C _b). This EOS does not call for any experimentally established material constant to describe the effect of porosity. Also its ability to describe the unloading behaviour distinguishes it from the presently available equations of state.     

New laser materials for diode pumped solid state lasers

Ytterbium (Yb³⁺) doped solid state lasers (e.g. Yb:YAG), pumped with InGaAs laser diodes, have been intensively and successfully developed recently. A search is in progress for novel ytterbium doped crystals possessing properties superior to known Yb doped gain media, or with properties enabling of Yb lasers with new capabilities. Several such materials have been identified and characterized in the past year.     

The use of an MHV-2 equation of state for modeling the thermodynamic properties of refrigerant mixtures

This paper reports on the development and application of a thermodynamic model based on the second-order Modified Huron Vidal equation of state (MHV-2) to predict the properties of ternary mixtures of the refrigerants R32, R125, and R134a. The mixing rules of this equation of state have been used to incorporate directly an activity-coefficient model for the excess Gibbs free energy. The parameters for the activity-coefficient model have been derived from experimental VLE data for binary mixtures. This methodology has enabled the production of a thermodynamically consistent model which can be used to predict the phase equilibria of R32/R125/R134a mixtures. The input data used in the model are presented in the paper and the predictions of the model are compared with available experimental data. The model has been used to predict the behavior of ternary refrigerant blends of R32/R125/R134a in fractionation scenarios, such as liquid charging and vapor leakage, which are of direct interest to the refrigeration industry. Details of these applications and comparisons with experimental data are discussed, along with other general uses of the thermodynamic model.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, USA.     

Novel synthesis methods for new materials in solid state chemistry

The most common method used for synthesizing inorganic solids is the so-called ‘ceramic method’ which involves synthesizing at elevated temperatures and leads to thermodynamically stable phases. This method has a serious limitation because many inorganic solids of current interest are rather metastable and consequently their preparation requires low temperature methods. In this article, we have reported some methods of synthesis which also include methods that belong to soft-chemistry routes. The selected examples presented in this paper are: (i) the intercalation and or deintercalation of oxygen in oxides by electrochemical oxidation or reduction in aqueous or nonaqueous solutions, (ii) the use of chemical agents such as NO₂ or borohydrides for obtaining oxides with tunneled and lamellar structures, (iii) a multistage synthesis processing for intercalating, in layered oxygenated materials, anionic species and acrylic monomers and polymers, (iv) the supercritical fluid processing for preparing nitrides, carbon-nitrides, lamellar oxides and oxy-(hydroxy-) fluorides, and (v) the mechanical alloying for synthesizing new Mg-based binary intermetallics.     

The high-pressure equation of state of solid molecular tritium

We have calculated the equation of state for solid molecular tritium using a semiempirical approach, closely guided by experimental results for H₂ and D₂. TheT=0 K isotherm is calculated from a self-consistent phonon model of the free energy. Temperature effects are treated by the Mie-Grüneisen model. A tabulation of pressure, bulk modulus, and thermal expansion is given for a dense set of molar volumes, as a function of temperature up toP=22 kbar.     

Thermoelectroelasticity theory for materials with memory

In this work the extended Tiersten's theory of thermoelectroelasticity for materials with memory is presented. Constitutive equations are derived for nonlinear dielectric materials that possess fading memory of past fields. The consequences of the second law of thermodynamics is studied. The analysis is based on Coleman's work, the entropy inequality proposed by Green and Lindsay and the extended Tiersten's theory of thermoelectroelasticity.     

Dynamic equation of state of a gas mixture containing solid particles

A dynamic equation of state is derived, describing the relationship between the pressure and volume of a thermal-nonequilibrium gas mixture. The methods of nonequilibrium thermodynamics are used to calculate the relaxation time.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 5, pp. 833–838, May, 1978.     

An improved experimental equation of state of solid hydrogen and deuterium

We have analyzed a large set of data in the literature as well as new data of our own to provide an improved equation of state of solid para-hydrogen and ortho-deuterium, with pressures ranging from 0 to 25 kbar (at the melting line). Results, including pressure, bulk modulus, and thermal expansion, are tabulated for a dense set of molar volumes as a function of temperature.Partial financial support provided by the Stichting FOM.     

Three-dimensional optical random access memory materials for use as radiation dosimeters

This article describes the development of the first three-dimensional optical random access memory (3D-ORAM) material and readout system for monitoring energetic neutrons. Two different photochromic dyes, 5'-chloro-6-nitro-1',3',3'-trimethylspiro-[2H-1-benzopyran-2,2'-in doline] (spirobenzopyran) and anthracene, have been investigated for use in these 3-D ORAM dosimeter materials. These dyes were immobilized in a poly(methyl methacrylate) support, and the resulting dosimeter materials were irradiated with neutrons from a Cf-252 source. Fluorescence measurements from the dosimeter show a dramatic decrease in the overall fluorescence intensity of the 3D-ORAM dosimeter exposed to the Cf-252, relative to a nonirradiated dosimeter. In addition, a two-photon excitation readout system has been developed for determining characteristics of the radiation that are necessary for estimating dose.     

Toward perfect antireflection coatings. 3. Experimental results obtained with the use of Reststrahlen materials

The equipment and methods used to produce wide-angle antireflection coatings based on Reststrahlen materials are described. The optical constants of the coating materials used in the construction of the multilayers were determined by spectrophotometric ellipsometry and are compared with the literature values. The measured performance of an experimentally produced antireflection coating is compared with the expected calculated performance. The reflectance is low over a wide range of angles, but only in the narrow-wavelength region at which the refractive index of the Reststrahlen material is close to unity.     

PE100管材料的聚集态结构和性能的固体NMR分析

PE100管材料基体树脂中界面区的含量比较高(高于10%),而完全无定形区的含量极低.界面区含量表征非晶区中运动部分受阻的链段所占的比重,因而上述结果意味着PE100管材料中非晶区中链段表现出强烈的缠结倾向.界面区的含量(或非晶区的组成特征)决定了材料的耐慢速裂纹增长性能,而固相区含量则决定了材料的力学强度,两种影响因素的平衡决定了最终管材料的长期使用性能.     

Analysis of the formed track in solid state materials using atomic force microscopy

The track formation in solid state materials, from the theoretical point of view, is still under study. One way to understand the track formation mechanisms and radiation damage of the charged particles in some materials such as polymers, glasses and minerals, is to analyse the surface topography effects. In this work, the track formation analysis in polycarbonate material is presented using an atomic force microscope (AFM) to characterise the evolution of the track on the material surface and beyond a thin layer of the surface material. The AFM is very useful to obtain valuable information at the level of the atomic structure of the materials and of the nuclear tracks, due to its high resolution and very easy operation involving also a simple sample preparation. The results show the development of the formed track by means of induced surface effects after being exposed to ionising radiation and chemical etching.     

Robust exponential attractors for the non-autonomous nonclassical diffusion equation with memory

The existence of a robust family of exponential attractors is established for the non-autonomous nonclassical diffusion equation with linear memory, while the nonlinearity is critical.