HALL-EFFECT AND SUBSTITUTION EFFECT IN PB2SR2Y1-XCAXCU3O8+DELTA

The Hall effect of ceramic samples of Pb2Sr2Y1-xCaxCu3O8 has been investigated for 0 less-than-or-equal-to x less-than-or-equal-to 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 less-than-or-equal-to x less-than-or-equal-to 0.5, where T(c) appears, R(H) increases with decreasing temperature again, and 1/R(H)e is expressed as alpha-T + beta (alpha > delta, beta > 0). The temperature coefficient-alpha 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.