Calculation of Electric Field Generated by Mechanical Stress in Bi1.8Pb0.2Sr2Ca2Cu3-xZnxO Superconducting Thin Films

Abstract

The mechanical properties of the  Bi_1.8Pb_0.2Sr₂Ca₂Cu_3-x Zn_xO  superconducting film was studied through Shear force tests as a function of displacement at different Zn concentrations (x=0.2, 0.4, 0.6, 0.8, 1). The examinations were carried out at Tehran Technological university the tests showed that the higher the Zn concentrations , the greater the strength of the sample to withstand the pressures, the break points of the sample were recorded at the  maximum  shear forces (2.5, 3, 5.7, 5.8, 6.5 N)  the corresponding concentrations Zn_x is (x=0.2,0.4,0.6,0.8,1) respectively. The electrical properties of samples ,were measured  by four probe  technique ,the values of T_C for variable Zn concentrations in Bi_1.8Pb_0.2Sr₂Ca₂Cu_3-xZn_xO thin film recorded (90,95 ,97,102)and superconducting behavior respectively. Bi_1.8Pb_0.2Sr₂Ca₂Cu_3-xZn_xO superconducting film samples were prepared by pulsed laser deposition PLD. Theoretically, we studied some of  the mechanical properties in more depth and based on the results of experimental  tests  of shear force (0.5, 1, 1.5, 2, 2.5, 3 , 3.5, 4 , 5 , 5.7 , 5.8 , 6 ,6.5)N   two stresses were calculated the first is the true stress σ_tru , which the sample fracture occurred and was calculated from the ratio of the force perpendicular to the cross-sectional area of the film and the second is the geometric stress σ_gE from the force ratio applied to the film area, also the  work done W to displace the perovskite lattice layers and the electric field E generated  by the effect of  true stress σ_tru  between the layers Finally ,a model of the perovskite lattice Bi_1.8 Pb_0.2Sr₂Ca₂Cu_3-xZnO is constructed showing the deformation caused by stress  (piezoelectric deformation ).