arXiv subjects

R. I. Gulyaeva

Publications and source records attributed to R. I. Gulyaeva.

3 recordsLinked to original sources

arXiv2017

XPS study of the chemical stability of DyBa2Cu3O6+δ superconductor

The chemical stability of the powder DyBa2Cu3O6+δ has been studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermal analysis at ambient conditions. The powder was subjected to mechanical processing in a ball mill-activator to accelerate chemical degradation. The kinetic regularities of hydrolytic decomposition of DyBa2Cu3O6+δ under the influence of air moisture have been determined. The resistive properties of DyBa2Cu3O6+δ to water have been found to be better, but not much different from analogous properties of YBa2Cu3O6+δ which is unstable in a wet environment. Chemical degradation of the material is triggered by crucial concentrating of water particles near the free surface of the solid reactant (due to their low diffusibility in the bulk) leading to rapid chemical decomposition of the respective regions.

cond-mat.mtrl-sci↗

arXiv2017

YBa2Cu3O6+d-originated attraction force giving rise to Meissner effect at 300 K

The exposure of YBCO to an air atmosphere at first at pH2O = 110 Pa and then at pH2O = 1 kPa has been used for uncharacteristic and unusual properties of YBCO to be observed. Among them there was an increased reactivity of YBCO with respect to water. Besides, it was experimentally obtained extremely excessive weight gain of hydrated YBCO samples that was not corresponding to the quantity of the absorbed water. Finally, we obtained the significant negative value of the room-temperature (RT) magnetic susceptibility in conventional magnetic study of the hydrated YBCO that was confirmed by the direct observation of decreasing weight of the same samples that were suspended above the source of controlled magnetic field (DC mode) at RT. All the results were explained on the basis of an approximate idea that there is a certain source of attractive force inside YBCO, acting on surrounding particles and bodies.

cond-mat.mtrl-sci↗

arXiv2009

The effect of anomalous adsorption of H2O and CO2 by pre-hydrated YBa_2Cu_3O_{6.53}

The results of a comprehensive study on the YBa_2Cu_3O_{6.53} oxide subjected to "mild" hydration (exposure at small values of pH2O) by a special technique have been reported. The material modified in this way acquires an interesting property; namely, in natural conditions it intensively absorbs large quantities of components (H2O and CO2) comprising the gas atmosphere. Arguments have been adduced that at least the water enters the crystal lattice of the yttrium-barium cuprate. This lattice is in the two-phase (tetragonal and orthorhombic) state: testing of the magnetic properties of the oxide has revealed the presence of antiferromagnetic and diamagnetic regions in this material.

cond-mat.mtrl-sci↗