Samples of Bi 1.6 Pb 0.4 Sr 1.8 Ba 0.2 Ca 2 Cu 3−x Ni x O 10+δ were prepared by solid-state reaction methods. Mechanical properties (Vickers microhardness, Young modulus, yield strength, fracture toughness and surface energy) by Vickers microhardness measurements have been carried out to examine the effects of Ni substitution. The results showed a deterioration of the mechanical properties with the enhancement of Ni content.

Solid state reaction method was used to prepare samples of Bi 1.6 Pb 0.4 Sr 1.8 Ba 0.2 Ca 2 Cu 2.2 Ni 0.8 O 10+δ. Superconducting and mechanical properties by Vickers microhardness measurements have been carried out to examine the effects of pressure. Electrical measurement demonstrates the best transition temperature was under 0.7 GPa. An improvement of mechanical properties was found when the pressure increases from 0.3 GPa to 0.9 GPa. On the other side an increases of the pressure to 1.1 GPa decrease in the micro hardness, Young modulus and yield strength.

In this paper, investigations were carried out on the effects of simultaneous partial substitution of Tl at the Hg site on the physical properties of an Hg1-xTlxBa2Ca2Cu3O8+δ cuprate superconductor with x= 0, 0.1, 0.2, 0.3 and 0.4. Two steps of the solid state reaction method were used to prepare samples in capsule. The results showed that the optimum sintering temperature was equal to 850 ᵒC and the sintering time was equal to 20 h for the prepared samples.       The best conditions for constitution and stabilization of the high Tc phase-1223 were obtained by investigating the effects of Tl substitution on Hg site and oxygen content (δ) on the superconducting properties.          Structural investigation revealed that all the samples have a tetragonal structure with two phases, namely an Hg-1223 high Tc phase as a main phase and an Hg-1212 low Tc phase. Besides, some impurity phases like CuO and CaHgO2 were found. The increase of Tl content in Hg1-xTlxBa2Ca2Cu3O8+δ compound from 0 to 0.4 caused a change in the lattice parameter, density of the unit cell (ρm), and c/a values.         HgBa2Ca2Cu3O8+δ compound exhibited a critical transition temperature that is equal to 115 K. On the other side, the results showed that the highest Tc was 119 K for Hg0.8Tl0.2 Ba2Ca2Cu3O8+δ. The oxygen content (δ= 0.46) was expected to be the optimum hole doping for Hg0.8Tl0.2 Ba2Ca2Cu3O8+δ compound, which  means in our opinion that  δ plays a remarkable role in the assessment of Tc.

High temperature superconductors with a nominal composition Hg1-xTlxBa2Ca2Cu3O8+δ for (0<x<0.4) were prepared by two-step solid state reaction in air. The effect of the substitution of Tl for Hg, oxygen content (δ) and sintering time (20-200h) on the Hg-12223 superconductivity system has been investigated to obtain the optimum conditions for the formation and stabilization of the high critical temperature (Tc).The results showed that the optimum sintering temperature for the prepared samples was equal to 880 °C, whereas the sintering time is equal to 100 h.The quantity of the element content for Hg1-xTlxBa2Ca2Cu3O8+δ system were carried out using x-ray fluorescence (XRF). X-ray diffraction (XRD) analysis showed a tetragonal structure with a high Tc phases (1223) as a dominant phase and low Tc phase (1212) addition to exist of some impurity phases for all samples. It was found that the change of the Tl concentrations of prepared samples produced a change in the lattice parameters, density ρm and c/a ratio. The highest Tc for HgBa2Ca2Cu3O8+δ composition was 118 K. The results for the doped samples, represented highest Tc equal to 124 K for Hg1-xTlx Ba2Ca2Cu3O8+δ sample with x=0.4.The oxygen content was not systematic changed but it played a great role in the evaluation of Tc.