Pressure and high-temperature superconductivity of hydrogen compounds

Boyko, Yu.I.; Богданов, В. В.; Вовк, Р. В.

doi:10.1063/10.0001061

Cited by 8 publications

(5 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here h is Planck's constant, m is the electron mass, r is the radius of the electron orbit in the atom (Bohr radius), n is the concentration of the electron "gas" [4,5]. Substituting into (2) the numerical values of the constants, and taking into account that n ≈ nat, where nat ≈ 1 ̸ a 3 ≈ 10 28 1/m 3 , a is the crystal lattice parameter, we have: Р ≈ 10 2 GPa.…”

Section: Changes In the Phonon Spectrum Of Metals And The Temperature...mentioning

confidence: 99%

Electroacoustic Effect and Electrical Superconductivity of Metals

Boyko,

Bogdanov,

Vovk

et al. 2023

View full text Add to dashboard Cite

The paper discusses the conditions under which superconductivity of metals would be detected at atmospheric pressure and at room temperature. One of the possible directions of research to achieve these conditions is to change the phonon spectrum of metals in order to increase the Debye temperature, and therefore to increase the temperature of the superconducting transition Tc. According to the idea of the work and to the estimates made in it, the maximum frequency of phonons nmax in metals can be increased by the short-term action of an external constant electric field (electric pulse). The duration of the pulse should be (10–5–10–7) s. The voltage of the constant electric field source is U » 1V. A decrease in the crystal lattice parameter should be accompanied by an increase in the maximum phonon frequency nmax and, accordingly, by an increase in the Debye temperature. The characteristic size of the sample, in which the change in electron concentration can be realized, should not exceed the length of electron shielding in metals, i. e. ≈ 10–8 m. The sequential action of a certain number of electric field pulses can maintain a superconducting state in a metal sample for some finite time.

show abstract

Section: Changes In the Phonon Spectrum Of Metals And The Temperature...mentioning

confidence: 99%

Electroacoustic Effect and Electrical Superconductivity of Metals

Boyko,

Bogdanov,

Vovk

et al. 2023

View full text Add to dashboard Cite

show abstract

“…We will state the main ideas and considerations in this regard, as well as make some quantitative estimates confirming the validity of such a conclusion. The pressure P, under which the conversion of any solid crystalline substance (dielectric, semiconductor, semimetal) into metal can be realized, is described by the following relation [6]:…”

Section: Change In the Energy Spectrum Of The Electronic Subsystem Ofmentioning

confidence: 99%

“…The magnitude of this pressure and, accordingly, the effectiveness of its action increase with decreasing crystal size and in the above-mentioned size range R for metals reaches the value Р≈10 7 -10 8 Ра [5]. Such pressure for some materials can significantly change the nature and the main parameters of their electronic energy spectrum, which in turn can cause a change in their electrical properties, in particular, cause the transition of low-dimensional crystals to the superconducting state [6].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Capillary (Laplace) pressure and superconductivity of nano-sized crystalline particles of semimetals

Boyko¹,

Богданов²,

Вовк³

et al. 2020

The Journal of v. N. Karazin Kharkiv National University, Series "Physics"

View full text Add to dashboard Cite

The possibility to the superconducting state transition at temperatures close to room temperature for nanoscale crystals of bismuth and antimony semimetals, as well as their alloys is discussed. All physical reasoning, as well as the estimates given in the paper, are based on the classical thermodynamics laws, as well as on the quantum theory of superconductivity (BCS theory) conclusions, which is based on the idea of electrons "pairing" (the Cooper pairs formation) as a result of electron-phonon interaction. It is shown that in nanocrystalline particles internal capillary compressive stresses act, the magnitude of which is sufficient for the transformation of semimetals into metals. This transition is accompanied by a change in the energy spectrum of electrons: "non-degenerate" semiconductors become metals in which the gas of "degenerate" electrons is characterized by a low Fermi energy. The latter circumstance causes an increase in the density of electronic states and enhances the electron-phonon interaction in metallized semimetals. As the initial chemical elements from which superconducting compounds can be synthesized under pressure, substances that allow the "collectivization" of electrons can be used. The most suitable substances for this are elements of the fifth group of the periodic system Bi, Sb, As, graphite, etc. They are characterized by a slight overlap of the valence and conduction zones, which leads, on the one hand, to the fact that they remain high conductors of electricity up to the absolute zero temperature, and on the other hand, they have a significantly lower density of charge carriers compared to metals. In addition, a specific structural state is formed in bismuth and antimony alloys at certain concentrations, which leads to a change in the nature of the phonon spectrum (the number of high-frequency phonons increases), which also enhances the electron-phonon interaction. All these changes in the energy spectrum and structural state of semimetals make it possible for nanocrystals to transition to the superconducting state at a temperature of  300 K.

show abstract

“…The use of high-pressure technologies to study the critical characteristics of high-temperature superconductor (HTSC) materials continues to be one of the most promising experimental techniques that allow not only checking the adequacy of theoretical models but also finding empirical ways to improve their electrical transport characteristics and increase critical parameters [1,2]. This is particularly important, given that, despite the 35-year history of intensive theoretical and experimental research (from the discovery of HTSC in 1986 [3]), it is not possible to overcome the threshold of 200 K of the critical temperature (T c ) [4,5]. In essence, the microscopic mechanism of HTSC remains unclear until now [1,6].…”

Section: Introductionmentioning

confidence: 99%

Effect of high pressure on temperature dependences of the resistivity in the ab-plane of Y0.77Pr0.23Ba2Cu3O7-δ single crystals

Chroneos

Khadzhai

Goulatis

et al. 2022

J Mater Sci: Mater Electron

Self Cite

View full text Add to dashboard Cite

In the present work, we investigated the influence of high hydrostatic pressure up to 11 kbar on the conductivity in the basal ab-plane of medium-doped with praseodymium (x≈0.23) single-crystal Y1-xPrxBa2Cu3O7-δ samples. It was determined that, in contrast to the pure YBa2Cu3O7-δsamples with the optimal oxygen content, the application of high pressure leads to the formation of phase separation in the basal plane of Y0.77Pr0.23Ba2Cu3O7-δ single crystals. Possible mechanisms of the effect of Pr doping and high pressure on the two-step resistive transition to the superconducting state are discussed. It was determined that in the normal state, the conductivity is metallic and is limited by phonons scattering (Bloch-Grüneisen regime) and defects. The fluctuation conductivity is considered within the Lorentz-Doniach model. Hydrostatic pressure, accompanied by a decrease in anisotropy, leads to a decrease in the residual and phonon resistances. Debye temperature and coherence length are independent of pressure. The applicability of the McMillan formula in the presence of significant anisotropy is discussed.

show abstract

Pressure and high-temperature superconductivity of hydrogen compounds

Cited by 8 publications

References 16 publications

Electroacoustic Effect and Electrical Superconductivity of Metals

Electroacoustic Effect and Electrical Superconductivity of Metals

Capillary (Laplace) pressure and superconductivity of nano-sized crystalline particles of semimetals

Effect of high pressure on temperature dependences of the resistivity in the ab-plane of Y0.77Pr0.23Ba2Cu3O7-δ single crystals

Contact Info

Product

Resources

About