Thermophysical properties of some key solids: An update

In 1985, the CODATA Bulletin published a Report of its Task Group on Thermophysical Properties of Solids which analyzed available data on, and gave recommended values for, the heat capacity of Cu, Fe, W, and Al₂O₃, the thermal expansion of Cu, Si, W, and Al₂O₃, the electrical resistivity of Cu, Fe, Pt, and W, the thermal conductivity of Al, Cu, Fe, and W, and the absolute thermopower of Pb, Cu, Pt, and W. The analysts for the different properties were R. B. Castanet, S. J. Collocott, P. D. Desai, C. Y. Ho, J. G. Hust, R. B. Roberts, C. A. Swenson, and G. K. White. The present paper is an updated version of the earlier report and includes more recent data which change some of the recommended values. notably the heat capacity of Cu and W and the thermal expansion of Si and W.     

Thermopower measurements on BiSrCaCuO system

We report thermoelectric power measurements on BiSrCaCuO (2212) superconducting oxide and compare the observed behaviour with that of the YBaCuO (123) system. The relative importance of phonon drag and diffusion thermopower contributions is evaluated for the two systems by analysing the data using a generalized expression of the typeS=αT+β/T. The thermopower enhancement effect just aboveT _c gives parameter values comparable to those of YBa₂Cu₃O_7−x system.     

Synthesis, Thermopower and Magnetic Properties of Mercury Deficient Hg-1201

Samples of Hg-1201 have been synthesized using the sealed-tube precursor-reactant method. The samples are mercury deficient, with the deficiency related to the ratio of precursor to reactant mass in the tube. The Curie constant in the normal state is found to evolve systematically with mercury content in a way that suggests a combination of structural mercury vacancies and phase segregation. Thermopower measurements are presented for samples over a range of doping levels.     

Exploration of highly correlated Co‐based quaternary Heusler alloys for spintronics and thermoelectric applications

The half‐metallic character of new quaternary Heusler alloys CoXMnAs (X = Ru, Rh) is established along with their thermoelectric, mechanical, and thermodynamic properties. The optimization of energy suggests that alloys are stable in Y2‐type structure with a ferromagnetic character. The electronic band profile through generalized gradient approximation and modified Becke‐Johnson potential indicates the metallic character of alloys. However, with inclusion of Hubbard potential to generalized gradient approximation, the alloys depict half‐metallic character with semiconducting nature in spin‐down state. The alloys possess high magnetic moment, CoRuMnAs has 5 μB, whereas CoRhMnAs has 6 μB, following Slater‐Pauling rule M_T = Z_T ? 24. The narrow band gap in spin‐down channel enhances the thermoelectric properties. The maximum value for thermopower (|S|) obtained is 44.3 and 53.44 μV/K for CoRuMnAs and CoRhMnAs, respectively. The variation of electrical conductivity, Seebeck coefficient, and figure of merit affirm increasing trend with temperature, which is a good indication of materials to be used in thermoelectric technology. The mechanical stability along with ductile nature of alloys is determined through elastic constants. Further, we have calculated thermodynamic properties and have established their dependence on temperature and pressure using quasi‐harmonic Debye model. The half‐metallic nature with efficient thermoelectric parameters strongly supports the possible application of alloys for spin devices and green energy generation.     

1000MW超超临界机组热控系统分析及设备选型

介绍目前几个已投产和即将投产的1000Mw超超临界机组控制及保护系统的特点、测点设置情况和现场总线技术的优缺点,分析超超临界机组在测温元件、变送器、仪表阀门、执行机构等设备选型方面的问题,并提出选型方案、建议及注意事项。     

火电厂竞价上网策略研究

讨论在电力市场逐步建立后,作为独立法人实体和市场行为主体的火电厂,在安全稳定生产的基础上,如何面对市场需要,采取适当的经济运行方式和灵活的报价方式,以争取上网电量的最大化和经济效益的最优化,并提出了预测各时段过际电价（既最高入围电价）的思路。     

Lithium solid electrolytes and their applications

The preparation, characterisation and applications of two systems of lithium ion conductors, lithium zinc germanate (Lisicon) and lithium germanate vanadate are described. Ionic conductivity studies include ac conductivity, thermopower andnmr which provide complementary information. High pressure studies and fabrication of a solid-state cell are also reported. An erratum to this article is available at .     

Enhancing Thermopower and Nernst Signal of High-Mobility Dirac Carriers by Fermi Level Tuning in the Layered Magnet EuMnBi2

Dirac/Weyl semimetals hosting linearly dispersing bands have received recent attention for potential thermoelectric applications, since their ultrahigh-mobility carriers could generate large thermoelectric and Nernst power factors. To optimize these efficiencies, the Fermi energy needs to be chemically controlled in a wide range, which is generally difficult in bulk materials because of disorder effects from the substituted ions. Here it is shown that the Fermi energy is tunable across the Dirac point for layered magnet EuMnBi₂ by partially substituting Gd³⁺ for Eu²⁺ in the insulating block layer, which dopes electrons into the Dirac fermion layer without degrading the mobility. Clear quantum oscillation observed even in the doped samples allows to quantitatively estimate the Fermi energy shift and optimize the power factor (exceeding 100 µ W K⁻² cm⁻¹ at low temperatures) in combination with the first-principles calculation. Furthermore, it is shown that Nernst signal steeply increases with decreasing carrier density beyond a simple theoretical prediction, which likely originates from the field-induced gap reduction of the Dirac band due to the exchange interaction with the Eu moments. Thus, the magnetic block layer provides high controllability for the Dirac fermions in EuMnBi₂, which would make this series of materials an appealing platform for novel transport phenomena.     

Thermophysical Properties of Some Key Solids

In 1995 the Committee on Data for Science and Technology (CODATA) published a Report of its Task Group on Thermophysical Properties of Solids which analyzed available data on, and gave recommended values for, the heat capacity of Al₂O₃, Cu, W, and Fe, the thermal expansion of Cu. Si, W, and Al₂O₃, the electrical resistivity of Cu, Fe, W. and Pt, the thermal conductivity of AI, Cu, Fe, and W, and the absolute thermopower of Pb, Cu, and Pt, The Chairman of the Task Group was Professor Y. S. Touloukian. until his death in 1981, and later was Dr, Merrill Minges, Since that publication there have been more measurements of heat capacity (Cu), thermal expansion (Si and W), and thermopower (W). particularly at high temperatures with subsecond techniques, which have led us to reanalyze some of the data and change some recommended values, Revised tables and some algebraic expressions are presented here.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.