Structural and electronic properties of expanding fluid metals

Structure and Electronic State in a Fluid Alkali Metal: Synchrotron Radiation Studies

Structure and electronic state in a fluid alkali metal have been investigated by using synchrotron radiation. X-ray diffraction and small angle X-ray scattering measurements of fluid rubidium (Rb) were carried out for observing local and intermediate atomic arrangements, and X-ray Compton scattering measurements were carried out for observing electronic state in the fluids. Variation in physical quantities obtained by these measurements has revealed a particular density range of the fluid, where the stability problem of the electron gas becomes an issue.

Experimental observation of density fluctuations in liquid metals associated with liquid-liquid, liquid-gas and metal-nonmetal transitions

We have developed a special technique and succeeded to carry out small-angle x-ray scattering measurements for some liquid metal systems. The purpose is to investigate effects of transitions such as liquid-liquid (LLT), liquid-gas (LGT) and metal-nonmetal (MNMT) transitions on mesoscopic density fluctuations in liquids. In liquid Te systems (Se-Te and Ge-Te mixtures), which show continuous LLT accompanying MNMT, parameters of density fluctuations show maxima almost in the middle of the transition, both in strength and spatial size. This work (and Kajihara et al 2012 Phys. Rev. B86 214202) was the first direct observation that density fluctuations exhibit maximum corresponding to LLT. However in this study, we could not clearly separate the effects of LLT and MNMT on the observed density fluctuations. Thus, we also investigated fluid Hg under high pressure and high temperature conditions, which shows MNMT near a critical point of LGT, to investigate how MNMT affects them. We observed distinct density fluctuations; a strength and a correlation length of them show maxima at around a critical isochore of LGT, and the former is basically consistent with a phase diagram (compressibility) of LGT; they do not show any peaks at MNMT region. Precise analysis revealed that MNMT only affects a shift of another parameter, a short-range correlation length. These results in fluid Hg indicate that the density fluctuations are mainly derived from a critical phenomena of LGT and MNMT does not play any critical role on them. We believe that the latter conclusion also holds true for liquid Te systems; MNMT plays no important role on the density fluctuations in liquid Te systems and LLT is the main origin of them.

Plasmons in Liquid Metals Studied by Inelastic X-ray Scattering

Plasmon is a collective excitation of electrons in materials. Since plasmon can be observed in a wide range of the phase diagram including the solid, liquid, and classical plasma phases, the investigation of the electronic states through the plasmon is of great significance in order to obtain a unified insight into the electronic states in various phases of matter. Inelastic X-ray scattering (IXS) is an ideal tool for such an investigation, because it can be applied to the samples in the liquid state and those in an extreme conditions. In this review, we discuss IXS results on the plasmons in liquid metals, and also describe a formulation to predict the plasmon energy and the lifetime in liquid metals. The formulation takes into account the effect of the ionic structure within the nearly free electron approximation, and reproduces well the experimental results.

Calculation of Thermal Pressure Coefficient of R11, R13, R14, R22, R23, R32, R41, and R113 Refrigerants by pVT Data

For thermodynamic performance to be optimized particular attention must be paid to the fluid’s thermal pressure coefficients and thermodynamic properties. A new analytical expression based on the statistical mechanics is derived for R11, R13, R14, R22, R23, R32, R41, and R113 refrigerants, using the intermolecular forces theory. In this paper, temperature dependency of the parameters of R11, R13, R14, R22, R23, R32, R41, and R113 refrigerants to calculate thermal pressure coefficients in the form of first order has been developed to second and third orders and their temperature derivatives of new parameters are used to calculate thermal pressure coefficients. These problems have led us to try to establish a function for the accurate calculation of the thermal pressure coefficients of R11, R13, R14, R22, R23, R32, R41, and R113 refrigerants based on statistical-mechanics theory for different refrigerants.