Possibility of existing brand-new type of attractive field in YBa2Cu3O6+δ

•An increased reactivity of YBCO with respect to water has been observed.•It has been found excessive weight gain of hydrated YBCO samples that is not corresponding to the quantity of the absorbed water.•A hydrated YBCO sample shows high-fields paramagnetic Meissner effect.•After removing the water dissolved in hydrated YBCO, the magnetic moment of YBCO not only sharply increases but also seemed to lose its connection with the crystal lattice. The exposure of YBCO to an air atmosphere at first at pH2O = 110 Pa and then at pH2O = 1 kPa was used for uncharacteristic and unusual properties of YBCO to be observed. For this purpose thermogravimetric, mass spectrometric, volumetric, magnetic, etc. analyses were carried out. One of the unusual properties observed in our work is an increased reactivity of YBCO with respect to water. It is accompanied by an extremely excessive weight gain of hydrated YBCO samples that is not corresponding to the quantity of the absorbed water. Besides that, unusual electric and magnetic properties have been recorded on these samples. All the results have been explained on the basis of an approximate idea that there is a certain source of attractive field inside YBCO, acting on surrounding particles and bodies. This field is likely to constitute the additional interaction between holes, besides electron-phonon coupling, that makes Cooper pairs in YBCO stable at high temperatures, giving rise to high Tc of this compound.