The current work involves the study of the substitution effect of calcium instead of lanthanum on the structural and electric characteristics at room of the HgBa2Ca2-1LaxCu3O8+ δ compound with (x = 0, 0.2, 0.4, 0.6 and 0.8). The specimens were manufactured via solid status reaction process. The results of X - radiation deviation showed for all samples a tetragonal system, containing the highest proportion of the pure (Hg - 1223) stage with low percentages for the minor phases (Hg - 1212, 1201) and appearance of some impurities, and the highest phase rate for the specimen at (x = 0.4) which is equal to (84.69%) and characterized by absence of impurities. The results of the measurement of the lattice constants, (c. 1 / a) and the density of mass shows that a sample with (x = 0.2) has the highest value (c / a = 4.602) and highest value of crystal size (D = 84.7 nm). The four - sensor procedure was achieved to detection the transition temperature Tc and the results confirmed the metal behavior of all samples. There was a change in the critical temperature, which increased from (111 to 119) Kelvin when the concentration of lanthanum increased from zero to 0. 2 and became 114 K at x = 0. 4 and then decreased to (105 and 98) Kelvin at x = 0.6 and 0.8.

Lattice Constants, Crystal Size, Tetragonal System, Structural and Electric Characteristics.