First-principles search of hot superconductivity in La-X-H ternary hydrides

Motivated by the recent claim of hot superconductivity with critical temperatures up to 550 K in La + x hydrides, we investigate the high-pressure phase diagram of compounds that may have formed in the experiment, using first-principles calculations for evolutionary crystal structure prediction and superconductivity. Starting from the hypothesis that the observed Tc may be realized by successive heating upon a pre-formed LaH10 phase, we examine plausible ternaries of lanthanum, hydrogen and other elements present in the diamond anvil cell: boron, nitrogen, carbon, platinum, gallium, gold. We find that only boron and, to a lesser extent, gallium form metastable superhydride-like structures that can host high-Tc superconductivity, but the predicted Tc’s are incompatible with the experimental reports. Our results indicate that, while the claims of hot superconductivity should be reconsidered, it is very likely that unknown H-rich ternary or multinary phases containing lanthanum, hydrogen, and possibly boron or gallium may have formed under the reported experimental conditions, and that these may exhibit superconducting properties comparable, or even superior, to those of currently known hydrides.

Determination of the SSM Processing Window

Identification of critical temperatures is paramount for semisolid processing. Application of the principles of differential calculus to identify these temperatures on semisolid transformation curves allows the semisolid metal (SSM) processing window to be determined. This paper synthesizes and organizes a methodology that can be used to this end, namely the differentiation method (DM). Examples are given of the application of the method to 356, 355, and 319 aluminum alloys, which are commonly used in SSM processing, and the results are compared with those of numerical simulations performed with Thermo-Calc® (under the Scheil condition). The DM is applied to experimental differential scanning calorimetry (DSC) heat-flow data for cooling and heating cycles under different kinetic conditions (5, 10, 15, 20, and 25 °C/min). The findings indicate that the DM is an efficient tool for identifying critical points such as the solidus, liquidus, and knee as well as tertiary transformations. The results obtained using the method agree well with those obtained using traditional techniques. The method is operator-independent as it uses well-defined mathematical/graphical criteria to identify critical points. Furthermore, the DM identifies an SSM processing window defined in terms of a higher and lower temperature for rheocasting or thixoforming operations (TSSML and TSSMH) between which the sensitivity is less than 0.03 °C-1 and, consequently, the process is highly controllable. This DM has already been published in a partial and dispersed way in different works in the past and the aim here is to present it in a more cohesive and didactic way, synthesizing the presented data and comparing them.

Basic Principles for Thermoplastic Parts Finishing With Impulse Thermal Energy Method

Impulse thermal energy method (ITEM) as modification of the thermal energy method that is successfully used for finishing is considered for application to thermoplastics. The chapter focuses to highlight the basic principles of the thermoplastics treatment by acting heat fluxes inherent to ITEM providing the time-controlled production of combustion species. The properties of thermoplastics and the requirements for their treatment have the greatest impact on processing settings. Thus, the questions of the choice of the preferred fuel mixture, the type of its ignition, and combustion have been studied. By means of numerical situating, the processes of melting and healing of pores during processing are investigated. A method of defining processing settings has been developed, taking into account the limitations on critical temperatures. The promising possibilities of ITEM in relation to the processing of thermoplastics parts obtained by additive technologies are outlined.

A New Interpretation of Contributions Presented at the Solvay Conference 1911. Can We Falsify the “Geocentric” Foundations of Quantum Mechanics in the Solar System?

We have studied the contributions and presentations published in the Proceedings of the Solvay Conference 1911. Based on the lecture of Ernest Solvay on the “gravito-matérialitique” we can distinguish two features of the Earth´s gravitational field – 1. “gravité réelle” described by the Newton´s gravitational law and 2. “gravité potentielle” acting as an agent of the self-organization on quantum particles and creating structures described by the Planck constant hEARTH. From the discussions followed after the presentations of Walther Nernst and Albert Einstein we interpreted the Nernst- Lindemann Formula for the specific heat of solids using the comment of Heike Kamerlingh Onnes (the discoverer of the superconductivity) as two transverse and one longitudinal oscillations of phonon in the surroundings at temperature T. In order to falsify this “geocentric” model of foundations of quantum mechanics in the spirit of Karl Popper we propose to initiate the CURE Project (China – USA – Russia – European Union) (cure = to solve a problem) in order to build quantum laboratories on different orbits around the Earth, on the surface of the Moon and Mars, and in the Lagrange points of the system the Earth – Moon and the Earth – Sun to get new experimental data for the specific heat of solids, the critical temperatures of superconductors, chemical and physical self-organized reactions (Liesegang rings, Belousov- Zhabotinsky waves, chemical clocks, Bose-Einstein condensates, de Broglie waves, etc.). There is space enough for all participants on this CURE Project to collect new valuable data describing this “hidden variable” presented by Ernest Solvay in his forgotten lecture in 1911.

Impact of age, sex, and size on the thermal tolerance of the adult black soldier fly (Diptera: Stratiomyidae)

Thermal stresses from both environmental conditions and organismal crowding are common in mass production of the black soldier fly, Hermetia illucens L. (Diptera: Stratiomyidae). In this study, upper and lower critical thermal (CT) limits (i.e. knockdown CTmax and CTmin) for the adult black soldier fly were determined. Impacts of size, age, and sex on these critical temperatures were also assessed. The CTmax ranged from 45.0-51.0 °C with larger and older adults having a ~1 °C higher CTmax than smaller and younger adults. However, no differences in the CTmax were found between sexes, regardless of age or size. The CTmin ranged from 8.0 to 13.0 °C with larger and older females having a ~1 °C higher CTmin than males and smaller or younger females. While reporting the upper and lower critical temperatures, this study also revealed the thermal breadth (i.e. the range of body temperatures over which organisms can locomote) for adult black soldier flies across age, sex, and size. Based on these data, and when recognising not all fly populations are the same, mass-rearing facilities should determine the CTmax and CTmin for their fly population in order to optimise mating and fertile egg production, and ultimately maximise profits and sales. One degree of temperature can be the difference between success and failure in industrialised facilities.

Analytical Expressions for Ising Models on High Dimensional Lattices

We use an m-vicinity method to examine Ising models on hypercube lattices of high dimensions d ≥ 3. This method is applicable for both short-range and long-range interactions. We introduce a small parameter, which determines whether the method can be used when calculating the free energy. When we account for interaction with the nearest neighbors only, the value of this parameter depends on the dimension of the lattice d. We obtain an expression for the critical temperature in terms of the interaction constants that is in a good agreement with the results of computer simulations. For d = 5,6,7, our theoretical estimates match the numerical results both qualitatively and quantitatively. For d = 3,4, our method is sufficiently accurate for the calculation of the critical temperatures; however, it predicts a finite jump of the heat capacity at the critical point. In the case of the three-dimensional lattice (d = 3), this contradicts the commonly accepted ideas of the type of the singularity at the critical point. For the four-dimensional lattice (d = 4), the character of the singularity is under current discussion. For the dimensions d = 1,2 the m-vicinity method is not applicable.

Potential Room Temperature Superconductivity in Clathrate Lanthanide/Actinides Octadechydrides at Extreme Pressures

Atomic metallic hydrogen (AMH) hosting high-temperature superconductivity has long been considered a holy grail in condensed matter physics and attracted great interest, but attempts to produce AMH remain in intense exploration and debate. Meanwhile, hydrogen-rich compounds known as superhydrides offer a promising route toward creating AMH-like state and property, as showcased by the recent prediction and ensuing synthesis of LaH10 that hosts extraordinary superconducting critical temperatures (Tc) of 250-260 K at 170-190 GPa. Here we show via advanced crystal structure search a series of hydrogen-superrich clathrate compounds MH18 (M: rare-earth/actinide metals) comprising H36-cage networks, which are predicted to host Tc up to 329 K at 350 GPa. An in-depth examination of these extreme superhydrides offers key insights for elucidating and further exploring ultimate phonon-mediated superconductivity in a broad class of AMH-like materials.

Combined Light and Electron Scattering for Exploring Proximity Effects on Hydrogen Absorption in Vanadium

We investigate proximity effects on hydrogen absorption in ultra-thin vanadium layers through combing light transmission and electron scattering. We compare the thermodynamic properties of the vanadium layers, which are based on the superlattice structure of Cr/V (001) and Fe/V (001). We find an influence of the proximity effects on the finite-size scaling of the critical temperatures, which can be explained by a variation of dead layers in the vanadium. In addition to this, the proximity effects on hydrogen absorption are also verified from the changes of excess resistivity.

DETERMINATION AND MODELING OF THE LIQUIDUS SURFACE, VAPOR PRESSURE AND IMMISCIBILITY BOUNDARIES IN THE Cu–Pb–S SYSTEM

For the first time using a membrane zero-manometer, the vapor pressure S2 over the surface of the PbS liquidus in the ternary system Cu–Pb–S were determined in the range 1100÷1400 K and 0÷760 mm Hg. Based on the thermodynamic calculation, the boundaries of the immiscibility of liquid alloys of the Cu–S, Pb–S, and Cu–Pb–S systems were determined and analytically described. Critical temperatures and pressures for immiscibility regions of sulfur-rich liquid alloys are characterized by high values: Tcr= 1520÷1880 K; Pcr=170÷510 atm. The crystallization surfaces of lead sulfide with electronic conductivity (p-type PbS) and with hole conductivity (n-type PbS) are calculated and analytically de-scribed, as well as the corresponding values of sulfur vapor pressure over the crystallization surface of lead sulfide. All analytical dependencies for 3D modeling were obtained and visualized using the OriginLab computer program