The in-plane resistivity ab (T) and the out-of-plane c (T) have been extensively measured for the pure single-crystal Bi 2 Sr 2 CaCu 2 O 8ϩ␦ (Bi2212) annealed at different oxygen pressure. The c (T) and anisotropy ͓ c (T)/ ab (T)͔ decreases rapidly with increasing carrier concentration. It is found that the out-of-plane resistivity decreases linearly with temperature down to about 120 K for the overdoped sample; its resistivity anisotropy is a weak temperature dependence. In the ab plane, the anisotropy is very weak and nearly independent of temperature. The data of c (T) and c (T)/ ab (T) are well fitted by the bipolaron theory proposed by Alexandrov and Mott. ͓S0163-1829͑98͒05945-1͔

The normal state resistivtity, upper critical field H c2 and Hall coefficientAbove 70 K, ρ(T ) fits well curve predicted by Bloch-Grüneisen theory consistently with electron-phonon scattering. H c2 (0) was estimated to be about 15.0 Tesla within the weak-coupling BCS theory, and the superconducting coherence length ξ(0) is approximately 47Å. R H of M gCN i 3 is negative for the whole temperature range which definitely indicates that the carrier in M gCN i 3 is electron-type. R H is temperature independent between T c and ∼ 140 K. Above ∼ 140 K, the magnitude of R H decreases as temperature rises. At T = 100 K, the carrier density is 1.0 × 10 22 /cm 3 , which is comparable with that in perovskite (Ba, K)BiO 3 , and less than that of the metallic binary M gB 2 .

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have been characterized by x-ray-diffraction and Ramanscattering measurements. It is found that the c-axis parameter decreases with increasing doping concentration ͑Pr or La͒ or oxygen content. The softening of the O(2) Sr A g mode corresponds to the decrease of the c-axis parameter. The effect of Pr substitution for Ca on this mode is smaller than that of La substitution for Sr. The shift of the O(1) Cu B 1g mode is related to the ionic size of the doping element. The O(3) Bi A g mode does not exhibit remarkable frequency shift since the Bi-O(3)-Bi force constant nearly remains unchanged upon doping. The effect of oxygen content on the O(2) Sr A g mode in the Bi2212 system is in contrast to that on the corresponding O(4) Ba A g mode in the Y123 system. Change in valence is the dominating effect causing the frequency shift of the O(2) Sr A g mode.

The thermopower and thermal conductivity of superconducting perovskite M gCN i 3 (T c ≈ 8 K) have been studied. The thermopower is negative from room temperature to 10 K. Combining with the negative Hall coefficient reported previously, the negative thermopower definetly indicates that the carrier in M gCN i 3 is electron-type. The nonlinear temperature dependence of thermopower below 150 K is explained by the electron-phonon interaction renormalization effects. The thermal conductivity is of the order for intermetallics, larger than that of borocarbides and smaller than M gB 2 . In the normal state, the electronic contribution to the total thermal conductivity is slightly larger than the lattice contribution. The transverse magnetoresistance of M gCN i 3 is also measured. It is found that the classical Kohler's rule is valid above 50 K. An electronic crossover occures at T * ∼ 50K, resulting in the abnormal behavior of resistivity, thermopower, and magnetoresistance below 50 K.