No abstract

In this research, the influence of calcium content on the binding energy and Cooper pairing is investigated for the high temperature superconducting () 1 2 3 7 Y Ca Ba Cu O x x − − δ compound where x = 0-0.2). This is done by using model considering that the formation of Cooper pairs happens during tunneling mechanism of holes between the two CuO 2 layers in the YCBCO crystal which are considered as forming adjacent potential wells. In this work, we make some modifications on the mentioned model and a modified equation for the binding energy as a function of Ca concentration is formulated to study the effect of Ca content by considering the change in the distance between the CuO 2 layer as a function of Ca. The calculated results agree very well with experimental results. This happens because the Ca 2+ substitution for Y 3+ leads to decreasing the distance between the two CuO 2 layers and hence potential energy of the system will be decreased. This leads to decreasing the binding energy between the Cooper pairs, and decreasing the distance between the two CuO 2 layers increasing the tunneling probability of holes between the two CuO 2 layers and thus increasing conduction mechanism and thus increasing current density, but this will decrease the energy gap and as a result decrease the critical temperature. The calculated results agree very well with experimental results.

In this paper the effect of Ca content in and the relation between electrostatic potential energy, critical temperature lattice parameters , volume lattice parameter , orthorhombicity, and the hole concentration is investigated by applying the ionic model to calculate the change in the electrostatic potential due to increasing the Ca content in the compound in. It is found that Ca 2+ substitution for Y 3+ leads to increase EP caused by increased ion volume and decrease of charge, this explains changes of superconducting structure parameters such as: lattice parameter ,volume lattice parameter , orthorhombicity. Furthermore decreases with increasing Ca content due to increase of EP which leads to change of the crystal structure and thus decreasing oxygen content and as a result decreasing of Finally considering all above effects the increase of EP will increase the superconducting current.