Hall effect and substitution effect in Pb₂Sr₂Y_1-xCa_xCu₃O_8+δ

The Hall effect of ceramic samples of Pb₂Sr₂Y_1-xCa_xCu₃O₈ has been investigated for 0 ≦ x ≦ 0.5. The Hall coefficient R_H is positive and decreases with increasing x, which is explained within the doped Mott-Hubbard model. For x < 0.1, R_H increases with decreasing temperature like a conventional semiconductor. For x= 0.1, R_H is almost constant. For 0.2 ≦ x ≦ 0.5, where T_c appears, R_H increases with decreasing temperature again, and 1/R_He is expressed as αT + β (α > 0, β > 0). The temperature coefficient α increases with increasing T_c. These temperature dependences of R_H are common to high-T_c oxides. Effects of the partial substitution of Fe, Co, Ni, Zn, Ga for Cu on T_c have been also studied for x = 0.5. The decrease in T_c is marked in order of Ga, Co, Zn, Ni, Fe. This is discussed in relation to experimental results on YBa₂Cu₃O₇.