A.V. Palnichenko

Influence of Rb, Cs, and Ba on the superconductivity of magnesium diboride

Magnesium diboride has been thermally treated in the presence of Rb, Cs, and Ba. The magnetic susceptibility shows the possible onsets of superconductivity in the resulting samples at 52 K (Rb), 58 K (Cs), and 45 K (Ba). Room-temperature 11B NMR indicates the cubic symmetry of the electric field gradient at the boron site for the samples reacted with Rb and Cs, in contrast to the axial symmetry in the initial MgB2 and in the sample treated with Ba.

Metastable superconductivity of the Al/Al2O3 interface

Superconductivity in the interface region between metallic Al and its oxide, Al2O3, has been detected at about 45 K in the measured dynamic magnetic susceptibility.

Intercalation of C60 fullerene crystals with calcium and barium via self-propagating high-temperature synthesis

We report a process for rapid intercalation of C60 fullerene crystals using self-propagating high-temperature synthesis. The process has been used to intercalate C60 fullerene crystals with calcium and barium. The superconducting transition temperatures of the intercalated fullerites have been measured, and the calcium-intercalated C60 fullerene crystals have been characterized by X-ray diffraction.

Superconductivity of Calcium C60 Intercalation Compound Synthesized by Shock-Wave Pressure

The C60 fullerite has been Ca-intercalated under high pressure up to 240 kbar induced by a pressure shock wave. Magnetometric measurements have revealed superconductivity of the as-prepared sample at 9.9 K. The sample relaxed under normal conditions in the helium atmosphere has exhibited traces of superconductivity with the onset at T = 30 K.

Influence of shock-wave pressure up to 65 GPa on the crystal structure and superconducting properties of MgB2

The influence of shock-wave pressure treatment up to 65 GPa on the crystal structure and the superconducting transition temperature of a polycrystalline MgB2 sample has been investigated. X-ray diffraction measurements have revealed that the shock-wave pressure does not result in any irreversible structural phase transitions in the MgB2, except for microdistortions formed in the crystal structure of the shock-wave pressure-treated MgB2 sample. This conclusion is in agreement with the results of superconducting transition temperature measurements of a MgB2 sample performed before and after its shock-wave pressure treatment.

Superconductivity of Cu/CuOx interface formed by shock-wave pressure

A mixture of powdered Cu and CuO has been subjected to shock-wave pressure of 350 kbar with following quenching of the vacuum-encapsulated product to 77 K. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ≈ 19 K, characterized by glassy dynamics of the shielding currents below Tc . Comparison of the ac susceptibility and the DC magnetization measurements infers that the superconductivity arises within the granular interfacial layer formed between metallic Cu and its oxides due to the shock-wave treatment.

Superconductivity of Al/Al2O3 interface formed under shock-wave conditions

A mixture of powdered Al and Al2O3 has been subjected to a shock-wave pressure of ≈ 170 kbar, followed by vacuum-encapsulating and quenching of the product to liquid nitrogen. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ≈ 37 K, characterized by glassy dynamics of the shielding currents below Tc. Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed between metallic Al and its oxide due to the shock-wave treatment.